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Jun.30.2020

Elsevier Drug Monographs

Lopinavir; Ritonavir

Indications/Dosage

Labeled

  • human immunodeficiency virus (HIV) infection

Off-Label

  • coronavirus disease 2019 (COVID-19)
  • human immunodeficiency virus (HIV) prophylaxis
  • severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection
† Off-label indication

For the treatment of human immunodeficiency virus (HIV) infection in combination with other antiretroviral agents

NOTE: The following abbreviations are used: nucleoside reverse transcriptase inhibitors (NRTIs); nonnucleoside reverse transcriptase inhibitors (NNRTIs); protease inhibitors (PIs).

NOTE: Lopinavir; ritonavir should not be administered once daily in pediatric patients due to inferior efficacy observed with once daily dosing compared with twice daily dosing.[28341]

Oral dosage (tablets)

Adults

400 mg/100 mg PO twice daily. Alternatively, 800 mg/200 mg PO once daily may be administered to patients with less than 3 lopinavir resistance-associated substitutions.[28341] NOTE: See dosing below for concomitant efavirenz, nelfinavir, nevirapine, carbamazepine, phenobarbital, or phenytoin therapy.

Adult pregnant females

400 mg/100 mg PO twice daily in patients with no documented lopinavir resistance-associated substitutions; there are insufficient data to recommend dosing in pregnant women with any lopinavir resistance-associated substitutions.[28341] HIV guidelines suggest increasing dose to 500 mg/125 mg or 600 mg/150 mg PO twice daily may be necessary in the 2nd and 3rd trimesters, especially for PI-experienced women and women with baseline viral loads more than 50 copies/mL. Once daily dosing is NOT recommended.[28341] [23512]

Children and Adolescents weighing more than 35 kg

400 mg/100 mg PO twice daily (for a BSA target of 300 mg/75 mg per m2/dose or 230 mg/57.5 mg per m2/dose).[28341] [42452] NOTE: See dosing below for concomitant efavirenz, nelfinavir, or nevirapine therapy.

Children and Adolescents weighing 31 to 35 kg

400 mg/100 mg PO twice daily (for a BSA target of 300 mg/75 mg per m2/dose) or 300 mg/75 mg PO twice daily (for a BSA target of 230 mg/57.5 mg per m2/dose).[28341] [42452] NOTE: See dosing below for concomitant efavirenz, nelfinavir, or nevirapine therapy.

Children weighing 26 to 30 kg

300 mg/75 mg PO twice daily (for a BSA target of 300 mg/75 mg per m2/dose or 230 mg/57.5 mg per m2/dose).[28341] [42452] NOTE: See dosing below for concomitant efavirenz, nelfinavir, or nevirapine therapy.

Children weighing 21 to 25 kg

300 mg/75 mg PO twice daily (for a BSA target of 300 mg/75 mg per m2/dose) or 200 mg/50 mg PO twice daily (for a BSA target of 230 mg/57.5 mg per m2/dose).[28341] [42452] NOTE: See dosing below for concomitant efavirenz, nelfinavir, or nevirapine

Children weighing 15 to 20 kg

200 mg/50 mg PO twice daily (for a BSA target of 300 mg/75 mg per m2/dose or 230 mg/57.5 mg per m2/dose).[28341] [42452] NOTE: See dosing below for concomitant efavirenz, nelfinavir, or nevirapine therapy.

Adults receiving concomitant carbamazepine, phenobarbital, or phenytoin

400 mg/100 mg PO twice daily. Do NOT administer once daily dosing.[28341]

Adults receiving concomitant efavirenz, nelfinavir, or nevirapine

500 mg/125 mg PO twice daily. Some experts would use 600 mg/150 mg PO twice daily for ease of tablet dosing.[28341] [42452]

Children and Adolescents weighing more than 45 kg receiving concomitant efavirenz, nelfinavir, or nevirapine

500 mg/125 mg PO twice daily. Some experts would use 600 mg/150 mg PO twice daily for ease of tablet dosing.[28341] [42452]

Children and Adolescents weighing 31 to 45 kg receiving concomitant efavirenz, nelfinavir, or nevirapine

400 mg/100 mg PO twice daily.[28341] [42452]

Children weighing 21 to 30 kg receiving concomitant efavirenz, nelfinavir, or nevirapine

300 mg/75 mg PO twice daily.[28341] [42452]

Children weighing 15 to 20 kg oreceiving concomitant efavirenz, nelfinavir, or nevirapine

200 mg/50 mg PO twice daily.[28341] [42452]

Oral dosage (oral solution)

Adults

400 mg/100 mg PO twice daily. Alternatively, 800 mg/200 mg PO once daily may be administered to patients with less than 3 lopinavir resistance-associated substitutions. The oral solution should be avoided during pregnancy due to the alcohol content.[28341] [51080] NOTE: See dosing below for concomitant efavirenz, nelfinavir, nevirapine, carbamazepine, phenobarbital, or phenytoin therapy.

Children and Adolescents

300 mg/75 mg per m2/dose PO twice daily is routinely used by many clinicians, especially for treatment-experienced patients; however, 230 mg/57.5 mg per m2/dose PO twice daily can be used for antiretroviral-naive patients.[42452] The manufacturer recommends 230 mg/57.5 mg per m2/dose PO twice daily. Alternatively, a weight based dose of 12 mg/3 mg per kg/dose PO twice daily for patients weighing less than 15 kg or 10 mg/2.5 mg per kg/dose PO twice daily for patients weighing 15 kg or more may be used. The maximum recommended dose is 400 mg/100 mg per dose.[28341] NOTE: See dosing below for concomitant efavirenz, nelfinavir, or nevirapine therapy.

Infants 7 to 11 months

300 mg/75 mg per m2/dose PO twice daily is recommended by the HIV guidelines.[42452] The manufacturer, however, recommends 230 mg/57.5 mg per m2/dose PO twice daily. Alternatively, a weight based dose of 12 mg/3 mg per kg/dose PO twice daily for patients weighing less than 15 kg or 10 mg/2.5 mg per kg/dose PO twice daily for patients weighing 15 kg or more may be used.[28341] Adjust doses frequently to accommodate growth. NOTE: See dosing below for concomitant efavirenz, nelfinavir, or nevirapine therapy.

Neonates 14 to 29 days postnatal age and 42 weeks postmenstrual age or older and Infants 1 to 6 months

300 mg/75 mg per m2/dose PO twice daily. Alternatively, a weight-based dose of 16 mg/4 mg per kg/dose PO twice daily may also be used. Adjust doses frequently to accommodate growth. Be aware of alcohol and propylene glycol intake; oral solution contains 42.4% (v/v) alcohol and 15.3% (w/v) propylene glycol.[28341] [42452] NOTE: See dosing below for concomitant efavirenz, nelfinavir, or nevirapine therapy.

Neonates 0 to 13 days postnatal age or younger than 42 weeks postmenstrual age

Use in this patient population is not recommended because of the potential for toxicities.[28341] [42452]

Adults receiving concomitant carbamazepine, phenobarbital, or phenytoin

400 mg/100 mg PO twice daily. Do NOT administer once daily dosing.[28341]

Adults receiving concomitant efavirenz, nelfinavir, or nevirapine

520 mg/130 mg PO twice daily.[28341]

Children and Adolescents weighing more than 45 kg receiving concomitant efavirenz, nelfinavir, or nevirapine

520 mg/130 mg PO twice daily.[28341] [42452]

Infants 7 to 11 months, Children, and Adolescents weighing 15 to 45 kg receiving concomitant efavirenz, nelfinavir, or nevirapine

11 mg/2.75 mg per kg/dose (or 300 mg/75 mg per m2/dose) PO twice daily.[28341] [42452]

Infants 7 to 11 months and Children weighing less than 15 kg receiving concomitant efavirenz, nelfinavir, or nevirapine

13 mg/3.25 mg per kg/dose (or 300 mg/75 mg per m2/dose) PO twice daily.[28341] [42452]

Neonates 14 to 29 days postnatal age and 42 weeks postmenstrual age or older and Infants 1 to 6 months receiving concomitant efavirenz, nelfinavir, or nevirapine

Lopinavir; ritonavir is not recommended in combination with these drugs.[28341]

For human immunodeficiency virus (HIV) prophylaxis†

INVESTIGATIONAL USE: For the treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection†, the virus that causes coronavirus disease 2019 (COVID-19)†

Oral dosage

Adults

Due to unfavorable pharmacodynamics and negative clinical trial data, the National Institutes of Health (NIH) COVID-19 treatment guidelines recommend against the use of lopinavir; ritonavir outside of clinical trials.[65314] Lopinavir 400 mg/ritonavir 100 mg PO twice daily for 10 to 14 days is being evaluated alone and in combination based on use in retrospective cohorts, historically controlled studies, case reports, and case series for other coronavirus infections, including the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) and the Middle East Respiratory Syndrome Coronavirus (MERS-CoV). Some low-level evidence suggests use may reduce the incidence of mortality associated with acute respiratory distress syndrome (ARDS).[65116] [65117] [65118] [65123] However, in a retrospective cohort study of hospitalized patients, no difference was noted in the duration of viral shedding after treatment with lopinavir; ritonavir (n = 29).[65146] Additionally, data from randomized trials involving hospitalized patients have found no clinical benefit with lopinavir; ritonavir as compared to usual standard of care alone.[65144] [65641]

Therapeutic Drug Monitoring

Suggested target trough concentration: 5,500 ng/mL

  • Routine monitoring of plasma concentrations of antiretroviral (ARV) drugs is generally not recommended in HIV-infected patients. However, therapeutic drug monitoring may be considered in the following situations [42452][46638]:
    • use of drugs with significant food and/or drug interactions
    • suboptimal treatment response
    • suspected suboptimal absorption, distribution, metabolism, or elimination of the drug
    • suspected concentration-dependent drug-associated toxicity
    • use of alternative dosing regimens and ARV combinations for which safety and efficacy have not been established in clinical trials
    • heavily pretreated patients experiencing virologic failure and who may have viral isolates with reduced susceptibility to ARVs
    • pregnant patients who have risk factors for virologic failure, particularly during the later stages of pregnancy
    • use of drugs in children with limited pharmacokinetic data and/or therapeutic experience

Maximum Dosage Limits

  • Adults

    800 mg/200 mg per day PO.

  • Geriatric

    800 mg/200 mg per day PO.

  • Adolescents

    more than 40 kg: 800 mg/200 mg per day.

    36 to 40 kg: 800 mg/200 mg per day PO for tablets; 20 mg/5 mg per kg/day or 460 mg/115 mg per m2/day PO for oral solution is recommended in the FDA-approved labeling; however, up to 600 mg/150 mg per m2/day for oral solution (Max: 800 mg/200 mg per day) is recommended in the HIV guidelines.

    31 to 35 kg: 600 mg/150 mg per day PO for tablets; 20 mg/5 mg per kg/day or 460 mg/115 mg per m2/day PO for oral solution is recommended in the FDA-approved labeling; however, up to 600 mg/150 mg per m2/day oral solution or 800 mg/200 mg per day for oral tablets is recommended in the HIV guidelines.

  • Children

    more than 40 kg: 800 mg/200 mg per day PO.

    36 to 40 kg: 800 mg/200 mg per day PO for tablets; 20 mg/5 mg per kg/day or 460 mg/115 mg per m2/day PO for oral solution is recommended in the FDA-approved labeling; however, up to 600 mg/150 mg per m2/day for oral solution (Max: 800 mg/200 mg per day) is recommended in the HIV guidelines.

    31 to 35 kg: 600 mg/150 mg per day PO for tablets; 20 mg/5 mg per kg/day or 460 mg/115 mg per m2/day PO for oral solution is recommended in the FDA-approved labeling; however, up to 600 mg/150 mg per m2/day for oral solution or 800 mg/200 mg per day for oral tablets is recommended in the HIV guidelines.

    26 to 30 kg: 600 mg/150 mg per day PO for tablets; 20 mg/5 mg per kg/day or 460 mg/115 mg per m2/day PO for oral solution is recommended in the FDA-approved labeling; however, up to 600 mg/150 mg per m2/day oral solution is recommended in the HIV guidelines.

    21 to 25 kg: 400 mg/100 mg per day PO for tablets; 20 mg/5 mg per kg/day or 460 mg/115 mg per m2/day PO for oral solution is recommended in the FDA-approved labeling; however, up to 600 mg/150 mg per m2/day for oral solution or 600 mg/150 mg per day for oral tablets is recommended in the HIV guidelines.

    15 to 20 kg: 400 mg/100 mg per day PO for tablets; 20 mg/5 mg per kg/day or 460 mg/115 mg per m2/day PO for oral solution is recommended in the FDA-approved labeling; however, up to 600 mg/150 mg per m2/day for oral solution is recommended in the HIV guidelines.

    less than 15 kg: 24 mg/6 mg per kg/day or 460 mg/115 mg per m2/day PO for oral solution is recommended in the FDA-approved labeling; however, up to 600 mg/150 mg per m2/day is recommended in the HIV guidelines. Safety and efficacy of the tablet formulation have not been established.

  • Infants

    older than 6 months: 24 mg/6 mg per kg/day PO or 460 mg/115 mg per m2/day PO for oral solution is recommended in the FDA-approved labeling; however, up to 600 mg/150 mg per m2/day is recommended in the HIV guidelines. Safety and efficacy of the tablet formulation have not been established.

    6 months or younger: 32 mg/8 mg per kg/day PO or 600 mg/150 mg per m2/day PO for oral solution. Safety and efficacy of the tablet formulation have not been established.

  • Neonates

    14 days postnatal age or older and 42 weeks postmenstrual age or older: 32 mg/8 mg per kg/day PO or 600 mg/150 mg per m2/day PO for oral solution. Safety and efficacy of other formulations have not been established.

    younger than 14 days or postmenstrual age younger than 42 weeks: Not recommended.

Patients with Hepatic Impairment Dosing

Lopinavir is metabolized by the liver. Use caution and close monitoring when administering to patients with mild to moderate hepatic impairment (Child-Pugh A and B), as increased drug concentrations may occur. Use in patients with severe hepatic impairment (Child-Pugh C) has not been evaluated.[28341]

Patients with Renal Impairment Dosing

Specific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are needed.[28341]

 

Intermittent Hemodialysis

Avoid once-daily dosing in patients on hemodialysis.[46638]

† Off-label indication
Revision Date: 06/30/2020, 11:26:26 AM

References

23512 - Panel on Treatment of Pregnant Women with HIV infection and Prevention of Perinatal Transmission. Department of Health and Human Services. Recommendations for the use of antiretroviral drugs in pregnant women with HIV infection and interventions to reduce perinatal HIV transmission in the United States. Available at https://aidsinfo.nih.gov/guidelines. Accessed Dec 19, 2019.28341 - Kaletra (lopinavir; ritonavir) tablet and solution package insert. North Chicago, IL: AbbVie Inc; 2020 Mar.42452 - Panel on Antiretroviral Therapy and Medical Management of HIV-infected Children. Guidelines for the use of antiretroviral agents in pediatric HIV infection. Available at https://files.aidsinfo.nih.gov/contentfiles/lvguidelines/PediatricGuidelines.pdf. Accessed May 11, 2020.46638 - Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the use of antiretroviral agents in adults and adolescents with HIV. Department of Health and Human Services. Available at https://aidsinfo.nih.gov/guidelines. Accessed Dec 19, 2019.51080 - Kaletra (lopinavir; ritonavir) capsule package insert. North Chicago, IL: AbbVie Inc; 2019 Aug.55597 - Kuhar DT, Henderson DK, Struble KA, et al. Updated US Public Health Service guidelines for the management of occupational exposure to Human Immunodeficiency Virus and recommendations for postexposure prophylaxis. Infect Control Hosp Epidemiol 2013;34:875-92.60367 - New York State Department of Health AIDS Institute. HIV prophylaxis following occupational exposure. New York State Department of Health October 2014.60431 - World Health Organization. Guidelines on post exposure prophylaxis for HIV and the use of co-trimoxazole prophylaxis for HIV-related infections among adults, adolescents and children: Recommendations for a public health approach-December 2014 supplement to the 2013 consolidated ARV guidelines. World Health Organization, 2014. Available at: http://www/who.int/hiv/pub/guidelines/arv2013/arvs2013upplement_dec2014/en/. Accessed December 11, 2015.61819 - Centers for Disease Control and Prevention, US Department of Health and Human Services. Guidelines for antiretroviral posteexposure prophylaxis after sexual, injection drug use, or other nonoccupational exposure to HIV - United States, 2016. MMWR 2016;65:458.65116 - Chu CM, Cheng VCC, Hung IFN, et al. Role of lopinavir/ritonavir in the treatment of SARS: Initial virological and clinical findings. Thorax 2004;59:252-256.65117 - Jin Y, Cai L, Cheng Z, et al. A rapid advice guideline for the diagnosis and treatment of 2019 coronavirus (2019-nCoV) infected pneumonia (standard version). Military Med Res 2020;7(1):4.65118 - Huang C, Wang Y, Li X, et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet 2020;395(10223):497-50665123 - World Health Organization (WHO). Coronavirus: landscape analysis of therapeutics as of 17 Februrary 2020. Retrieved March 16, 2020. Available on the World Wide Web at https://www.who.int/blueprint/priority-diseases/key-action/Table_of_therapeutics_Appendix_17022020.pdf?ua=1.65144 - Cao B, Wang Y, Wen D, et al. A trial of lopinavir-ritonavir in adults hospitalized with severe Covid-19. N Engl J Med 2020;382(19):1787-1799.65146 - Zhou F, Yu T, Du R, et al. Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study. The Lancet 2020.65314 - COVID-19 Treatment Guidelines Panel. Coronavirus Diseases 2019 (COVID-19) Treatment Guidelines. National Institutes of Health. Accessed September 1, 2020. Available at on the World Wide Web at: https://covid19treatmentguidelines.nih.gov/.65641 - Nuffield Department of Population Health. No clinical benefit from use of lopinavir-ritonavir in hospitalised COVID-19 patients studied in RECOVERY. Retrieved June 30, 2020. Available on the World Wide Web at: https://www.recoverytrial.net/news/no-clinical-benefit-from-use-of-lopinavir-ritonavir-in-hospitalised-covid-19-patients-studied-in-recovery

How Supplied

Lopinavir, Ritonavir Oral capsule

Kaletra 133.3mg-33.3mg Capsule (00074-3959) (AbbVie US LLC) (off market)

Lopinavir, Ritonavir Oral solution

Kaletra 80mg-20mg/mL Solution (00074-3956) (AbbVie US LLC) nullKaletra 80mg-20mg/mL Solution package photo

Lopinavir, Ritonavir Oral solution

Lopinavir/Ritonavir 80mg-20mg/mL Solution (00527-1947) (Lannett Company, Inc.) null

Lopinavir, Ritonavir Oral tablet

Kaletra 100mg-25mg Tablet (00074-1575) (AbbVie US LLC) null

Lopinavir, Ritonavir Oral tablet

Kaletra 100mg-25mg Tablet (00074-0522) (AbbVie US LLC) null

Lopinavir, Ritonavir Oral tablet

Kaletra 200mg-50mg Tablet (00074-6799) (AbbVie US LLC) null

Lopinavir, Ritonavir Oral tablet

Kaletra 200mg-50mg Tablet (00074-2605) (AbbVie US LLC) null

Lopinavir, Ritonavir Oral tablet

Kaletra 200mg-50mg Tablet (55289-0947) (PD-Rx Pharmaceuticals, Inc.) null

Description/Classification

Description

Lopinavir; ritonavir is indicated for use in combination with other antiretroviral medications to treat HIV-1 infections in adults and pediatric patients 14 days and older. Lopinavir is an antiretroviral protease inhibitor. It is formulated with a small amount of ritonavir to increase and maintain adequate lopinavir concentrations. Lopinavir is the active component of the lopinavir; ritonavir formulation.

 

Updates for coronavirus disease 2019 (COVID-19):

Due to unfavorable pharmacodynamics and negative clinical trial data, the National Institutes of Health (NIH) COVID-19 treatment guidelines recommend against the use of lopinavir; ritonavir outside of clinical trials.[65314] In a randomized controlled trial [i.e., Randomised Evaluation of COVid-19 thERapY (RECOVERY)] of hospitalized patients with COVID-19, treatment with lopinavir; ritonavir (n = 1,596) provided no clinical benefit over usual care alone (n = 3,376). The preliminary data from this study found no difference in the 28-day mortality between patients treated with lopinavir; ritonavir and recipients of usual care alone (22.1% vs. 21.3%; RR 1.04; 95% CI, 0.91 to 1.18; p = 0.58).[65641] In another randomized, controlled, open-label trial involving hospitalized patients with confirmed SARS-CoV-2 infection (n = 199), treatment with lopinavir; ritonavir was not associated with a difference from the standard of care in the time to clinical improvement (median, 16 days versus 16 days; hazard ratio 1.31; 95% CI, 0.95 to 1.80; p = 0.09). Additionally, mortality at 28 days was similar between groups (19.2% vs. 25%, respectively) and the percentages of patients with detectable viral RNA were similar. In a modified ITT analysis, lopinavir; ritonavir had a median time to clinical improvement that was shorter by 1 day (hazard ratio, 1.39%; 95% CI, 1 to 1.91).[65144]

Classifications

  • General Anti-infectives Systemic
    • Antivirals For Systemic Use
      • HIV Antivirals
        • Combination HIV Antivirals
          • Protease Inhibitor Combinations
Revision Date: 07/01/2020, 01:41:12 PM

References

65144 - Cao B, Wang Y, Wen D, et al. A trial of lopinavir-ritonavir in adults hospitalized with severe Covid-19. N Engl J Med 2020;382(19):1787-1799.65314 - COVID-19 Treatment Guidelines Panel. Coronavirus Diseases 2019 (COVID-19) Treatment Guidelines. National Institutes of Health. Accessed September 1, 2020. Available at on the World Wide Web at: https://covid19treatmentguidelines.nih.gov/.65641 - Nuffield Department of Population Health. No clinical benefit from use of lopinavir-ritonavir in hospitalised COVID-19 patients studied in RECOVERY. Retrieved June 30, 2020. Available on the World Wide Web at: https://www.recoverytrial.net/news/no-clinical-benefit-from-use-of-lopinavir-ritonavir-in-hospitalised-covid-19-patients-studied-in-recovery

Administration Information

General Administration Information

For storage information,  see the specific product information within the How Supplied section.

Route-Specific Administration

Oral Administration

Oral Solid Formulations

  • Tablets: May be taken with or without food. Administered whole; do not crush, break, or chew.[28341]

Oral Liquid Formulations

Oral solution

  • Administer with food to enhance absorption.
  • Always administer using a calibrated oral dosing syringe or the provided dosing cup. The oral solution is highly concentrated and contains lopinavir 80 mg/ritonavir 20 mg per mL. Pay close attention to dosage of the oral solution, especially in pediatric patients, to ensure appropriate administration and to avoid overdosage.
  • The oral solution contains approximately 42% (v/v) alcohol and 15% (w/v) propylene glycol; caution is advised when administering to patients 14 days to 6 months of age. Additionally, the oral solution should be avoided during pregnancy due to the alcohol content.[42452]
  • The poor palatability of the oral solution may be difficult to overcome. Options to improve tolerability include numbing the taste buds with ice chips prior to administration, masking the taste by administering with sweet or tangy foods, chocolate syrup, or peanut butter, or flavoring the solution by the pharmacist prior to dispensing.[42452]
  • Because the oral solution contains ethanol and propylene glycol, it is not recommended for use with polyurethane feeding tubes due to potential incompatibility. Feeding tubes compatible with ethanol and propylene glycol, such as silicone and polyvinyl chloride (PVC), can be used for administration of lopinavir; ritonavir oral solution. Follow instructions for use of the feeding tube to administer the medication.[28341]

Clinical Pharmaceutics Information

From Trissel's 2‚Ñ¢ Clinical Pharmaceutics Database
  • [object Object]
Revision Date: 04/06/2020, 04:09:21 PMCopyright 2004-2020 by Lawrence A. Trissel. All Rights Reserved.

References

28341 - Kaletra (lopinavir; ritonavir) tablet and solution package insert. North Chicago, IL: AbbVie Inc; 2020 Mar.42452 - Panel on Antiretroviral Therapy and Medical Management of HIV-infected Children. Guidelines for the use of antiretroviral agents in pediatric HIV infection. Available at https://files.aidsinfo.nih.gov/contentfiles/lvguidelines/PediatricGuidelines.pdf. Accessed May 11, 2020.

Adverse Reactions

Mild

  • abdominal pain
  • alopecia
  • amenorrhea
  • anorexia
  • anxiety
  • appetite stimulation
  • arthralgia
  • asthenia
  • back pain
  • breast enlargement
  • Cushingoid features
  • diarrhea
  • dizziness
  • dysgeusia
  • dyspepsia
  • fatigue
  • fever
  • flatulence
  • folliculitis
  • gastroesophageal reflux
  • gonadal suppression
  • gynecomastia
  • headache
  • infection
  • insomnia
  • libido decrease
  • maculopapular rash
  • menorrhagia
  • myalgia
  • nausea
  • night sweats
  • pruritus
  • rash
  • seborrhea
  • tinnitus
  • tremor
  • urticaria
  • vertigo
  • vomiting
  • weakness
  • weight gain
  • weight loss
  • xerosis
  • xerostomia

Moderate

  • anemia
  • bleeding
  • cholangitis
  • colitis
  • constipation
  • diabetes mellitus
  • elevated hepatic enzymes
  • fecal incontinence
  • furunculosis
  • gastritis
  • hematoma
  • hematuria
  • hemorrhoids
  • hepatitis
  • hepatomegaly
  • hyperamylasemia
  • hyperbilirubinemia
  • hypercholesterolemia
  • hyperglycemia
  • hyperlipidemia
  • hypernatremia
  • hypertension
  • hypertriglyceridemia
  • hyperuricemia
  • hyponatremia
  • hypophosphatemia
  • impotence (erectile dysfunction)
  • jaundice
  • leukopenia
  • lipodystrophy
  • lymphadenopathy
  • migraine
  • neutropenia
  • oral ulceration
  • peripheral neuropathy
  • PR prolongation
  • QT prolongation
  • steatosis
  • stomatitis
  • thrombocytopenia

Severe

  • angioedema
  • AV block
  • bradycardia
  • cardiomyopathy
  • diabetic ketoacidosis
  • erythema multiforme
  • GI bleeding
  • lactic acidosis
  • myocardial infarction
  • osteonecrosis
  • pancreatitis
  • peptic ulcer
  • renal failure (unspecified)
  • rhabdomyolysis
  • seizures
  • Stevens-Johnson syndrome
  • thrombosis
  • torsade de pointes
  • toxic epidermal necrolysis
  • vasculitis
  • visual impairment

Adverse events affecting the reproductive system have been reported following use of lopinavir; ritonavir. During clinical trials, less than 2% of lopinavir; ritonavir recipients experienced reproductive adverse events including impotence (erectile dysfunction) (1.7%), libido decrease (0.7%), male gonadal suppression (0.8%), amenorrhea (1.7%), and menorrhagia (1.7%).[28341] [51080]

Pancreatitis, in some cases fatal, has been observed in 1.7% of patients receiving treatment with lopinavir; ritonavir. Marked triglyceride elevations is a risk factor for the development of pancreatitis; marked triglyceride elevations with the development of pancreatitis has occurred with lopinavir; ritonavir. Patients with advanced HIV disease may be at increased risk of elevated triglycerides and pancreatitis, and patients with a history of pancreatitis may be at increased risk for recurrence. If clinical symptoms (nausea/vomiting, abdominal pain) or lab abnormalities (hyperamylasemia or increased serum lipase) suggestive of pancreatitis occur, evaluate the patient and hold lopinavir; ritonavir and other antiretroviral therapy as clinically appropriate. In clinical trials with adults, hyperamylasemia  (more than 2-times the upper limit of normal) was noted in 3% to 8% of patients. In clinical trials of pediatric patients who received lopinavir; ritonavir oral solution, hyperamylasemia (more than 2.5-times the upper limit of normal) was reported in 7% of patients. In clinical trials with adults, elevated lipase (more than 2-times the upper limit of normal) was reported in 1% to 5% of patients.[28341] [51080]

Gastrointestinal (GI) related disorders were among the most frequently reported adverse events during lopinavir; ritonavir clinical trials, and included diarrhea (19.5% adults; pediatrics 12%), nausea (10.3%), vomiting (6.8% adults; 21% pediatrics), abdominal pain (6.1%), gastroenteritis and colitis (2.5%), and dyspepsia (2%). Other reported GI adverse events include constipation (1%), duodenitis (0.8%), abdominal distension (1.3%), fecal incontinence (0.2%), gastric or peptic ulcer (0.2%), gastritis (0.8%), gastroesophageal reflux disease (1.5%), hemorrhoids (1.5%), flatulence (1.4%), oral ulceration (0.9%), GI bleeding (0.5%), rectal bleeding (0.5%), stomatitis (0.9%), and xerostomia (0.3%).[28341] [51080]

Hyperlipidemia, with large increases in total cholesterol and triglyceride concentrations, has been reported during treatment with lopinavir; ritonavir. In clinical trials in adults, hypercholesterolemia (greater than 300 mg/dL) was reported in 3% to 27% of treatment-naive patients receiving lopinavir; ritonavir (vs. 5% of control group patients) and in 6% to 39% of treatment-experienced patients (vs. 21% control group). In clinical trials of pediatric patients who received lopinavir; ritonavir oral solution, hypercholesterolemia (greater than 300 mg/dL) was reported in 3% of patients. Also, in adults, hypertriglyceridemia (greater than 750 mg/dL) was reported in 3% to 29% of treatment-naive patients receiving lopinavir; ritonavir (vs. 1% control group) and in 5% to 36% of treatment-experienced patients (vs. 21% control group). Marked triglyceride elevations is a risk factor for the development of pancreatitis; marked triglyceride elevations with the development of pancreatitis has occurred with lopinavir; ritonavir. Lipid disorders should be managed as clinically appropriate, taking potential drug interactions into account.[28341] [51080]

Elevated hepatic enzymes have been reported during clinical trials of lopinavir; ritonavir, with elevations in SGOT/AST (range: 1% to 10% lopinavir; ritonavir-treated patients vs. 4% to 11% control patients) and SGPT/ALT (range: 1% to 11% vs. 4% to 13%). Hyperbilirubinemia was reported in 1% of adult patients in trials (3% of pediatrics), while elevated GGT was noted in 10% to 29% of adult patients. Hepatitis (3.5%), jaundice, hepatomegaly (0.2%), hepatic steatosis (0.1%), and cholangitis (0.1%) were also reported in patients receiving lopinavir; ritonavir during clinical trials. Patients with underlying hepatitis B or C or marked transaminase elevations prior to treatment may be at increased risk for developing further transaminase elevations or hepatic decompensation. There have been postmarketing reports of hepatic dysfunction, including some fatalities, which have generally occurred in patients with advanced HIV disease taking multiple concomitant medications and who have underlying chronic hepatitis or cirrhosis. However, elevated hepatic enzymes (with or without elevated bilirubin), leading to serious hepatic dysfunction in some cases, have been reported in patients without hepatitis.[28341] [51080]

Rash was reported in up to 3.8% of adult patients and 12% of pediatric patients receiving lopinavir; ritonavir during clinical trials. Other dermatologic reactions reported in less than 2% of patients during clinical trials include alopecia (0.4%), dry skin (xerosis), eczema (1.9%), exfoliative dermatitis (1.9%), furunculosis, night sweats (1.6%), pruritus (1.1%), maculopapular rash, and seborrhea (1.9%). Stevens-Johnson syndrome, toxic epidermal necrolysis (TEN), and erythema multiforme have been noted in postmarketing reports.[28341] [51080]

Musculoskeletal and generalized adverse reactions reported by recipients of lopinavir; ritonavir during clinical trials included fatigue and asthenia (7.6%), fever, arthralgia and back pain (6.4%), myalgia (1.8%), elevated creatine phosphokinase (more than 4-times upper limits of normal; 4% to 5%), muscle weakness and spasms (1.3%), rhabdomyolysis (0.7%), and osteonecrosis (0.1%).[28341] [51080]

Cardiovascular adverse events reported in patients receiving lopinavir; ritonavir during clinical trials included hypertension (1.8%), deep vein thrombosis (0.7%), myocardial infarction (0.4%), AV block (0.1%), tricuspid valve incompetence (0.1%), capillaritis and vasculitis (0.1%). Bradyarrhythmias (bradycardia), PR prolongation, QT prolongation, and torsade de pointes have been reported in postmarketing surveillance of lopinavir; ritonavir; however, causality has not been established. Lopinavir; ritonavir was evaluated for QT prolongation in a randomized, placebo- and moxifloxacin- (400 mg once-daily) controlled, crossover study in 39 healthy adults; QT intervals were measured on the third day. Patients received lopinavir; ritonavir at normal doses (400 mg/100 mg twice daily) and supratherapeutic doses (800 mg/200 mg twice daily). The maximum mean (95% upper confidence bound) difference in QT interval in patients versus placebo after baseline correction was 5.3 (8.1) milliseconds in patients receiving normal doses of lopinavir; ritonavir and 15.2 (18.0) milliseconds in patients receiving supratherapeutic doses. Lopinavir; ritonavir 800 mg/200 mg twice daily resulted in a Cmax that was 2-fold higher than observed with approved once and twice daily regimens at steady state.[28341] [51080]

Dysgeusia was reported in 22% of pediatric patients, and ageusia was noted in 0.7% of adults who received lopinavir; ritonavir during clinical trials.[28341] [51080]

Adverse events affecting the nervous system and special senses reported during lopinavir; ritonavir clinical trials included headache (including migraine, 6.3%), insomnia (3.8%), abnormal dreams (0.7%), anxiety (3.9%), dizziness (1.7%), peripheral neuropathy (2%), cerebral vascular event (0.2%), convulsion or seizures (0.3%), and tremor (0.3%). Visual impairment (0.3%), vertigo (0.3%), and tinnitus (0.2%) have also been reported.[28341] [51080]

In patients receiving lopinavir; ritonavir, neutropenia (less than 750 neutrophils/mm3) was reported in 1% to 5% of adults. Neutrophil counts less than 0.4 x 109/L were reported in 2% of pediatric patients who received lopinavir; ritonavir oral solution in clinical trials. In addition, 4% of pediatric patients who received lopinavir; ritonavir oral solution in clinical trials report thrombocytopenia (platelet counts less than 50,000/mm3). Anemia was noted in 2.1% of adult drug recipients, with 1% to 2% reporting hemoglobin concentrations less than 80 g/L. Leukopenia (1.7%) and lymphadenopathy (1.3%) have also been observed in adults.[28341] [51080]

Increased bleeding, including spontaneous skin hematoma and hemarthrosis, has been reported in patients with HIV and hemophilia (type A and B) being treated with protease inhibitors. The majority of patients have been able to continue taking their protease inhibitor therapy in spite of the bleeding events; some patients received additional coagulation factors. A causal relationship with lopinavir; ritonavir has not been established.[28341] [51080]

A lipodystrophy syndrome (2.2%) consisting of redistribution and accumulation of body fat including central obesity, dorsocervical fat enlargement (buffalo hump), peripheral wasting, facial wasting, breast enlargement, gynecomastia, and other cushingoid features have been reported in patients receiving long-term highly active antiretroviral therapy (HAART) that includes protease inhibitors. This syndrome may be associated with metabolic complications such as insulin resistance and dyslipidemia, but not always. The mechanism and long-term consequences are not known. A causal relationship has not been established. Changes in HAART to reverse lipodystrophy should probably be avoided unless the patient finds the changes in body fat intolerable and more conservative interventions fail.[28341] [51080]

Anorexia or decreased appetite (2%) with weight loss (2.3%) was observed in adult patients receiving lopinavir; ritonavir during clinical trials. Other metabolic and nutritional disorders reported in lopinavir; ritonavir recipients included appetite stimulation (0.2%) with weight gain (0.8%) and lactic acidosis (0.4%).[28341] [51080]

In clinical trials, hyperglycemia (glucose more than 250 mg/dL) was observed in 1% to 5% of patients and diabetes mellitus was observed in 1.1% of patients receiving lopinavir; ritonavir in combination with other antiretrovirals. New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with postmarketing use of protease inhibitors. Diabetic ketoacidosis has also occurred. Initiation or adjustment of hypoglycemic therapy is required in some patients after beginning protease inhibitor treatment. In some patients who have discontinued protease inhibitor therapy, hyperglycemia has persisted. However, a causal relationship has not been established. It should also be noted that many of these patients have confounding medical conditions that require therapy with drugs that have been associated with the development of diabetes mellitus or hyperglycemia.[28341] [51080]

In clinical trials of pediatric patients who received lopinavir; ritonavir oral solution, hypernatremia (sodium more than 149 mEq/L) and hyponatremia (less than 130 mEq/L) were reported in 3% of patients each. Additional laboratory abnormalities reported in adults during lopinavir; ritonavir clinical trials include hypophosphatemia (less than 1.5 mg/dL; up to 2%) and hyperuricemia (more than 12 mg/dL; up to 5%).[28341] [51080]

Upper respiratory tract infection (13.9%), lower respiratory tract infection (7.7%), and skin infection (cellulitis and folliculitis; 3.3%) were observed in adults receiving treatment with lopinavir; ritonavir during clinical trials. Viral infections were reported during clinical trials in pediatric patients.[28341] [51080]

Renal and urinary disorders reported in adult patients during lopinavir; ritonavir trials included renal failure (unspecified) (1.2%), hematuria (0.8%), and nephritis (0.1%). Creatinine clearance of less than 50 mL/min was noted in 2% to 3% of adult patients in trials.[28341] [51080]

Adverse events, including death, have resulted from accidental overdose of the lopinavir; ritonavir oral solution in young children. In one case, a 2.1 kg infant experience fatal cardiogenic shock 9 days after receiving a dose 10-fold above the recommended lopinavir dose. Other adverse events occurring in infants receiving unintentional overdoses include bradycardia, complete AV block, cardiomyopathy, lactic acidosis, CNS depression, respiratory complications, and acute renal failure (unspecified). Health care providers are advised to use caution when calculating and administering the oral solution to young children. Further, because the lopinavir; ritonavir solution contains a high concentration of alcohol 42.4% (v/v) and propylene glycol 15.3% (w/v), the manufacturer recommends evaluating all medications being given to the infant to ensure an alcohol and propylene glycol overdose does not occur. If an overdose does occur, administer supportive measures and monitor the patient's vital signs. Gastric lavage and activated charcoal may aid in the removal of unabsorbed drug. The use of dialysis is unlikely to be beneficial as lopinavir is highly protein-bound; however, excess alcohol and propylene glycol may be removed by dialysis.[28341]

Hypersensitivity reactions, including angioedema and urticaria, were reported in 2.7% of patients receiving lopinavir; ritonavir during clinical trials.[28341] [51080]

Revision Date: 07/17/2020, 01:27:18 PM

References

28341 - Kaletra (lopinavir; ritonavir) tablet and solution package insert. North Chicago, IL: AbbVie Inc; 2020 Mar.51080 - Kaletra (lopinavir; ritonavir) capsule package insert. North Chicago, IL: AbbVie Inc; 2019 Aug.

Contraindications/Precautions

Absolute contraindications are italicized.

  • alcoholism
  • apheresis
  • autoimmune disease
  • AV block
  • bradycardia
  • breast-feeding
  • cardiac disease
  • cardiomyopathy
  • celiac disease
  • children
  • diabetes mellitus
  • diabetic ketoacidosis
  • females
  • fever
  • geriatric
  • Graves' disease
  • Guillain-Barre syndrome
  • heart failure
  • hemophilia
  • hepatic disease
  • hepatitis
  • hepatitis B and HIV coinfection
  • hepatitis C and HIV coinfection
  • human immunodeficiency virus (HIV) infection
  • human immunodeficiency virus (HIV) infection resistance
  • hypercholesterolemia
  • hyperglycemia
  • hyperlipidemia
  • hyperparathyroidism
  • hypertriglyceridemia
  • hypocalcemia
  • hypokalemia
  • hypomagnesemia
  • hypothermia
  • hypothyroidism
  • immune reconstitution syndrome
  • infants
  • jaundice
  • long QT syndrome
  • myocardial infarction
  • neonates
  • pancreatitis
  • pheochromocytoma
  • pregnancy
  • QT prolongation
  • rheumatoid arthritis
  • sickle cell disease
  • sleep deprivation
  • stroke
  • systemic lupus erythematosus (SLE)

Unplanned antiretroviral therapy interruption may be necessary for specific situations, such as serious drug toxicity, intercurrent illness or surgery precluding oral intake, severe hyperemesis gravidarum unresponsive to antiemetics, or drug non-availability. If short-term treatment interruption (i.e., less than 1 to 2 days) is necessary, in general, it is recommended that all antiretroviral agents be discontinued simultaneously, especially if the interruption is because of serious toxicity. However, if a short-term treatment interruption is anticipated in the case of elective surgery, the pharmacokinetic properties and food requirements of specific drugs should be considered. When the antiretroviral regimen contains drugs with differing half-lives, stopping all drugs simultaneously may result in functional monotherapy of the drug with the longest half-life. For example, after discontinuation, the duration of detectable serum concentrations of efavirenz and nevirapine ranges from less than 1 week to more than 3 weeks. Simultaneously stopping all drugs in a regimen containing these agents may result in functional monotherapy with the NNRTI and may increase the risk of NNRTI-resistant mutations. Planned long-term treatment interruptions are not recommended due to the potential for HIV disease progression (i.e., declining CD4 counts, viral rebound, acute viral syndrome), development of minor HIV-associated manifestations or serious non-AIDS complications, development of drug resistance, increased risk of HIV transmission, and increased risk for opportunistic infections. If therapy must be discontinued, counsel the patient on the potential risks and closely monitor for any clinical or laboratory abnormalities.[46638][42452]

Lopinavir; ritonavir should be used with caution in patients with pre-existing hepatitis. Patients with underlying hepatitis prior to treatment may be at increased risk for developing further enzyme elevations or hepatic decompensation. All patients presenting with HIV infection should be screened for hepatitis B virus (HBV) coinfection to assure appropriate treatment. Patients with hepatitis B and HIV coinfection should be started on a fully suppressive antiretroviral (ARV) regimen with activity against both viruses (regardless of CD4 counts and HBV DNA concentrations). HIV treatment guidelines recommend these patients receive an ARV regimen that contains a dual NRTI backbone of tenofovir alafenamide with emtricitabine or tenofovir disoproxil fumarate with either emtricitabine or lamivudine. If tenofovir cannot be used, entecavir should be used in combination with a fully suppressive ARV regimen (note: entecavir should not be considered part of the ARV regimen). Avoid using single-drug therapy to treat HBV (i.e., lamivudine, emtricitabine, tenofovir, or entecavir as the only active agent) as this may result in HIV resistant strains. Further, HBV treatment regimens that include adefovir or telbivudine should also be avoided, as these regimens are associated with a higher incidence of toxicities and increased rates of HBV treatment failure. Most coinfected patients should continue treatment indefinitely with the goal of maximal HIV suppression and prevention of HBV relapse. If treatment must be discontinued, monitor transaminase concentrations every 6 weeks for the first 3 months, and every 3 to 6 months thereafter. For patients who refuse a fully suppressive ARV regimen, but still requires treatment for HBV, consider 48 weeks of peginterferon alfa; do not administer HIV-active medications in the absence of a fully suppressive ARV regimen. Instruct coinfected patients to avoid consuming alcohol, and offer vaccinations against hepatitis A and hepatitis B as appropriate.[46638] [28341] [51080] [34362]

Lopinavir; ritonavir should be used with caution in patients with pre-existing hepatic disease (e.g., alcoholism), liver enzyme abnormalities (e.g., jaundice), or hepatitis. Patients with underlying hepatitis B or C or marked elevations in liver enzymes prior to treatment may be at increased risk for developing further enzyme elevations or hepatic decompensation. There have been postmarketing reports of hepatic dysfunction, including some fatalities. These have generally occurred in patients with advanced HIV disease taking multiple concomitant medications in the setting of underlying chronic hepatitis or cirrhosis; however, elevated hepatic enzymes (with or without elevated bilirubin), leading to serious hepatic dysfunction in some case, have been reported in patients without underlying hepatitis as early as 7 days after the initiation of lopinavir; ritonavir. Of note, lopinavir; ritonavir was initiated with other antiretrovirals. A causal relationship has not been established. Increased monitoring of LFTs should be considered in these patients, especially during the first several months of treatment.[28341] [51080]

Patients with advanced acquired immunodeficiency syndrome (AIDS) may be at increased risk for developing hypertriglyceridemia and pancreatitis. Patients who exhibit signs or symptoms of pancreatitis (nausea, vomiting, abdominal pain, abnormal serum lipase or amylase concentrations) should discontinue treatment with lopinavir; ritonavir. Fat redistribution and hyperlipidemia have become increasingly recognized side effects with the use of protease inhibitors. Triglyceride and cholesterol testing should be performed prior to beginning lopinavir; ritonavir and at regular intervals during treatment. According to CDC guidelines, patients with hypertriglyceridemia or hypercholesterolemia should be evaluated for risks for cardiovascular events and pancreatitis. If a patient develops hyperlipidemia during treatment with a protease inhibitor, possible interventions include dietary modification, use of lipid lowering agents, or discontinuation of the protease inhibitor. Clinicians should be aware of the potential drug interaction between certain cholesterol-lowering agents and the lopinavir; ritonavir combination.[28341] [51080]

Patients with diabetes mellitus or hyperglycemia may experience an exacerbation of their condition with lopinavir; ritonavir treatment. In some cases, diabetic ketoacidosis has occurred. Further, reports of new-onset diabetes mellitus have been associated with protease inhibitor therapy. Either initiation or dose adjustments of insulin or oral hyperglycemic agents may be required. Drug recipients should be monitored closely for new-onset diabetes mellitus, diabetic ketoacidosis, or hyperglycemia.[28341] [51080]

Protease inhibitors such as lopinavir; ritonavir should be used cautiously in patients with hemophilia A or B due to reports of spontaneous bleeding episodes requiring treatment with additional factor VIII. In many cases, treatment with protease inhibitors was continued or restarted. A causal relationship has not been established.[28341] [51080]

Testing for human immunodeficiency virus (HIV) infection resistance is recommended in all antiretroviral treatment-naive patients at the time of HIV diagnosis, regardless of whether treatment will be initiated. Additionally, perform resistance testing prior to initiating or changing any HIV treatment regimen.[42452] [46638] Transmission of drug-resistant HIV strains has been both well documented and associated with suboptimal virologic response to initial antiretroviral therapy. In high-income countries (e.g., US, some European countries, Australia, Japan), approximately 10% to 17% of treatment-naive individuals have resistance mutations to at least 1 antiretroviral drug; up to 8% (but generally less than 5%) of transmitted viruses will exhibit resistance to drugs from more than 1 class. Therefore, resistance testing at baseline can help optimize treatment and, thus, virologic response. In the absence of therapy, resistant viruses may decline over time to less than the detection limit of standard resistance tests, but may still increase the risk of treatment failure when therapy is eventually initiated. Thus, if therapy is deferred, resistance testing should still be performed during acute HIV infection with the genotypic resistance test result kept in the patient's medical record until it becomes clinically useful. Additionally, because of the possibility of acquisition of another drug-resistant virus before treatment initiation, repeat resistance testing at the time therapy is initiated would be prudent. Varying degrees of cross-resistance among protease inhibitors have been observed. Continued administration of lopinavir; ritonavir following loss of viral suppression may increase the likelihood of antimicrobial resistance to other protease inhibitors.[46638]

Administering lopinavir; ritonavir oral solution to neonates with a postnatal age of less than 14 days or a postmenstrual age (first day of the mother's last menstrual period to birth plus the time since birth) of less than 42 weeks may result in significant alcohol and propylene glycol-related toxicities; use is not recommended. If the benefits of using the oral solution in infants immediately after birth outweighs the potential risk, the manufacturer recommends monitoring for increases in serum osmolarity, serum creatinine, and for adverse events such as hyperosmolarity, lactic acidosis, renal toxicity, CNS depression (stupor, coma, apnea), seizures, hypotonia, cardiac arrhythmias (ECG changes), and hemolysis. When dosing and administering the oral solution to any pediatric patient, use caution to avoid an overdosage. The solution contains approximately 42% (v/v) alcohol and 15% (w/v) propylene glycol; an accidental overdosage by a young child could result in significant propylene glycol or alcohol-related toxicities including death. For patients between the ages 14 days and 6 months, health care providers are advised to calculate the total amounts of alcohol and propylene glycol from all medications that are being administered to patient. In children, lopinavir; ritonavir dosages are either based on weight or body surface area (BSA). Typically, a child younger than 12 years will receive less than 5 mL of solution, unless certain enzyme-inducing drugs are prescribed or the child weighs 40 kg or more; the oral solution is highly concentrated and contains lopinavir 80 mg/ritonavir 20 mg per mL. In infants and children 6 months to 12 years of age, the adverse events reported during clinical trials were similar to adults.[28341]

Antiretroviral therapy should be provided to all women during pregnancy, regardless of HIV RNA concentrations or CD4 cell count. Using highly active antiretroviral combination therapy (HAART) to maximally suppress viral replication is the most effective strategy to prevent the development of resistance and to minimize the risk of perinatal transmission. In treatment-naive women, begin HAART as soon as pregnancy is recognized or HIV is diagnosed, without waiting for the results of resistance testing; subsequent modifications to the treatment regimen should be made once the test results are available. Women who are currently receiving antiretroviral treatment when pregnancy is recognized should continue their treatment regimen if it is currently effective in suppressing viral replication; consider resistance testing if HIV RNA concentrations are more than 500 copies/mL. For women not currently receiving HAART, but who have previously received treatment, obtain a complete and accurate history of all prior antiretroviral regimens used and results of prior resistance testing, and perform resistance testing if HIV RNA concentrations are more than 500 copies/mL; treatment should be initiated prior to receiving resistance test results. Available data from the Antiretroviral Pregnancy Registry, which includes more than 1,400 1st trimester exposures to lopinavir-containing regimens, have shown no difference in the risk of overall major birth defects when compared to the 2.7% background rate among pregnant women in the US. When lopinavir; ritonavir exposures occurred in the 1st trimester, the prevalence of defects was 2.1% (30 out of 1,418 births; 95% CI: 1.4, 3.0). Administer lopinavir; ritonavir twice daily in pregnant patients with no documented lopinavir-associated resistance substitutions; there are insufficient data to recommend dosing for pregnant patients with any documented lopinavir-associated resistance substitutions. Once daily lopinavir; ritonavir dosing is NOT recommended in pregnancy. No dosing adjustment is required for patients during the postpartum period. Avoid use of lopinavir; ritonavir oral solution during pregnancy due to the alcohol content.[28341] [47165] Regular laboratory monitoring is recommended to determine antiretroviral efficacy. Monitor CD4 counts at the initial visit and at least every 3 months during pregnancy; consideration may be given to monitoring every 6 months in patients on HAART with consistently suppressed viral loads and a CD4 count well above the opportunistic infection threshold. Monitor plasma HIV RNA at the initial visit, 2 to 4 weeks after initiating or changing therapy, monthly until undetectable, then at least every 3 months during pregnancy, and at 34 to 36 weeks gestation. Perform antiretroviral resistance assay (genotypic testing) at baseline in all women with HIV RNA concentrations greater than 500 copies/mL, unless they have already been tested for resistance. First-trimester ultrasound is recommended to confirm gestational age and provide an accurate estimation of gestational age at deliver. A second-trimester ultrasound can be used for both anatomical survey and determination of gestational age in those patients not seen until later in gestation. Perform standard glucose screening in women receiving antiretroviral therapy at 24 to 28 weeks gestation, although it should be noted that some experts would perform earlier screening with ongoing chronic protease inhibitor-based therapy initiated prior to pregnancy, similar to recommendations for women with high-risk factors for glucose intolerance. All pregnant women should be counseled about the importance of adherence to their antiretroviral regimen to reduce the potential for development of resistance and perinatal transmission. It is strongly recommended that antiretroviral therapy, once initiated, not be discontinued. If a woman decides to discontinue therapy, a consultation with an HIV specialist is recommended. It is strongly recommended that health care providers report cases of antenatal antiretroviral drug exposure to the Antiretroviral Pregnancy Registry; telephone 800-258-4263; fax 800-800-1052; the Antiretroviral Pregnancy Registry is also accessible via the Internet.[23512] [27468] [28341]

To reduce the risk of postnatal transmission, mothers with HIV within the United States are advised by the Centers for Disease Control and Prevention to avoid breast-feeding. This recommendation applies to both untreated women and women who are receiving antiretroviral therapy. If a mother with HIV opts to breast-feed, the infant should undergo immediate diagnostic and virologic HIV testing. Testing should continue throughout breast-feeding and up to 6 months after cessation of breast-feeding. For expert consultation, health care workers may contact the Perinatal HIV Hotline (888-448-8765).[42452] There are limited data regarding lopinavir; ritonavir use of during breast-feeding, and excretion into human breast milk is unknown. In 1 study, breast milk from mothers receiving lopinavir; ritonavir were analyzed with high-performance liquid chromatography and tandem mass spectrometry; the analysis failed to detect either drug in any of the 60 samples. Antiretroviral medications whose passage into human breast milk have been evaluated include nevirapine, zidovudine, lamivudine, and nelfinavir.[28341] [46936] [46675] [46679] [46680] [46682]

Ritonavir prolongs the PR interval in some patients, and postmarketing cases of 2nd- or 3rd-degree AV block have been reported. Lopinavir; ritonavir should be used with caution in patients with cardiac disease such as underlying structural heart disease, preexisting conduction system abnormalities, ischemic heart disease, and cardiomyopathy, as these patients may be at increased risk for developing cardiac conduction abnormalities. The impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers, beta-adrenergic blockers, digoxin, and atazanavir) has not been evaluated; however, concomitant administration with such drugs should be undertaken with caution, particularly with those drugs metabolized by cytochrome P450 3A4 isoenzymes. Clinical monitoring is recommended.[28315] [51080]

Cases of QT prolongation and torsade de pointes (TdP) have been reported during postmarketing surveillance. In general, lopinavir; ritonavir should not be used unmonitored in patients with known QT prolongation, with ongoing proarrhythmic conditions that may increase the risk of developing TdP, or receiving drugs that prolong the QT interval.[28341] [51080] Obtain a pre-treatment QTc using a standard 12-lead ECG, telemetry, or mobile ECG device. Obtain baseline electrolytes, including calcium, magnesium, and potassium. Determine if the patient is currently on any QT-prolonging medications that can be discontinued. Document high-risk cardiovascular and comorbid conditions. If the baseline QTc is 500 msec or more and/or the patient has an inherent tendency to develop an exaggerated QTc response (i.e., change of 60 msec or more), correct contributing electrolyte abnormalities, review and discontinue other unnecessary QTc prolonging medications, and proceed with close QTc surveillance. Obtain an initial on-therapy QTc approximately 2 to 4 hours after the first dose and then again at 48 and 96 hours after treatment initiation. If the baseline QTc is 460 to 499 msec (prepubertal), 470 to 499 msec (postpubertal males), or 480 to 499 msec (postpubertal females), correct contributing electrolyte abnormalities, review and discontinue other unnecessary QTc prolonging medications, and obtain an initial on-therapy QTc 48 and 96 hours after treatment initiation. If the baseline QTc is less than 460 msec (prepubertal), less than 470 msec (postpubertal males), or less than 480 msec (postpubertal females), correct electrolyte abnormalities and obtain an initial on-therapy QTc 48 and 96 hours after treatment initiation.[65170] Use lopinavir; ritonavir with caution in patients with conditions that may increase the risk of QT prolongation including congenital long QT syndrome, bradycardia, AV block, heart failure, stress-related cardiomyopathy, myocardial infarction, stroke, hypomagnesemia, hypokalemia, hypocalcemia, or in patients receiving medications known to prolong the QT interval or cause electrolyte imbalances. Females, geriatric patients, patients with sleep deprivation, pheochromocytoma, sickle cell disease, hypothyroidism, hyperparathyroidism, hypothermia, systemic inflammation (e.g., human immunodeficiency virus (HIV) infection, fever, rheumatoid arthritis, systemic lupus erythematosus (SLE), and celiac disease) and patients undergoing apheresis procedures (e.g., plasmapheresis [plasma exchange], cytapheresis) may also be at increased risk for QT prolongation.[28341] [28432] [28457] [56592] [65180]

Immune reconstitution syndrome has been reported in patients treated with combination antiretroviral therapy. During the initial phase of HIV treatment, patients whose immune system responds to antiretroviral therapy may develop an inflammatory response to indolent or residual opportunistic infections (such as progressive multifocal leukoencephalopathy (PML), mycobacterium avium complex (MAC), cytomegalovirus (CMV), Pneumocystis pneumonia, or tuberculosis (TB)), which may necessitate further evaluation and treatment.[34362] In addition, autoimmune disease (including Graves' disease, Guillain-Barre syndrome, and polymyositis) may also develop; the time to onset is variable and may occur months after treatment initiation.[28341]

HIV treatment guidelines recommend all patients presenting with HIV infection undergo testing for hepatitis C, with continued annual screening advised for those persons considered high risk for acquiring hepatitis C. If hepatitis C and HIV coinfection is identified, consider treating both viral infections concurrently. For most patients, the benefits of concurrent therapy outweighs the potential risks (i.e., drug-induced hepatic injury, complex drug interactions, overlapping toxicities); therefore, it is recommended to initiate a fully suppressive antiretroviral (ARV) therapy and a hepatitis C regimen in all coinfected patients regardless of CD4 count. However, for antiretroviral naive patients with CD4 counts greater than 500 cells/mm3, consideration may be given to deferring ARV until the hepatitis C treatment regimen has been completed. Conversely, for patients with CD4 counts less than 200 cells/mm3, consider delaying initiation of the hepatitis C treatment regimen until the patient is stable on fully suppressive ARV regimen. Instruct coinfected patients to avoid consuming alcohol, and offer vaccinations against hepatitis A and hepatitis B as appropriate.[46638]

Revision Date: 07/17/2020, 01:25:32 PM

References

23512 - Panel on Treatment of Pregnant Women with HIV infection and Prevention of Perinatal Transmission. Department of Health and Human Services. Recommendations for the use of antiretroviral drugs in pregnant women with HIV infection and interventions to reduce perinatal HIV transmission in the United States. Available at https://aidsinfo.nih.gov/guidelines. Accessed Dec 19, 2019.27468 - APR Steering Committee and Advisory Committee. The Antiretroviral Pregnancy Registry (The Antiretroviral Pregnancy Registry is a collaboration of product manufacturers managed by PharmaResearch Corporation). Issued December 2013. Retrieved April 2, 2014. Available on the World Wide Web at: www.apregistry.com.28315 - Norvir (ritonavir capsules) package insert. North Chicago, IL: AbbVie Inc; 2019 Dec.28341 - Kaletra (lopinavir; ritonavir) tablet and solution package insert. North Chicago, IL: AbbVie Inc; 2020 Mar.28432 - Roden, DM. Drug-induced prolongation of the QT interval. New Engl J Med 2004;350:1013-22.28457 - Crouch MA, Limon L, Cassano AT. Clinical relevance and management of drug-related QT interval prolongation. Pharmacotherapy 2003;23:881-908.34362 - Panel on Opportunistic Infections in HIV-Infected Adults and Adolescents. Guidelines for the prevention and treatment of opportunistic infections in adults and adolescents with HIV: recommendations from the Centers for Disease Control and Prevention, the National Institutes of Health, and the HIV Medicine Association of the Infectious Diseases Society of America. Accessed May 26, 2020. Available at http://aidsinfo.nih.gov/guidelines.42452 - Panel on Antiretroviral Therapy and Medical Management of HIV-infected Children. Guidelines for the use of antiretroviral agents in pediatric HIV infection. Available at https://files.aidsinfo.nih.gov/contentfiles/lvguidelines/PediatricGuidelines.pdf. Accessed May 11, 2020.46638 - Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the use of antiretroviral agents in adults and adolescents with HIV. Department of Health and Human Services. Available at https://aidsinfo.nih.gov/guidelines. Accessed Dec 19, 2019.46675 - Centers for Disease Control and Prevention: Breastfeeding recommendation for human immunodeficiency virus (HIV), and acquired immunodeficiency virus (AIDS). Retrieved November 9, 2011. Available on the World Wide Web at: http://www.cdc.gov/breastfeeding/disease/hiv.htm.46679 - Musoke P, Guay LA, Bagenda D, et al. A phase I/II study of the safety and pharmacokinetics of nevirapine in HIV-1-infected pregnant Ugandan women and their neonates (HIVNET 006). AIDS 1999;13(4):479-486.46680 - Moodley J, Moodley D, Pillay K, et al. Pharmacokinetics and antiretroviral activity of lamivudine alone or when coadministered with zidovudine in human immunodeficiency virus type-1-infected pregnant women and their offspring. J Infec Dis 1998;178:1327-1333.46682 - Colebunders R, Hodossy B, Burger D, et al. The effect of highly active antiretroviral treatment on viral load and antiretroviral drug levels in breast milk. AIDS 2005;19(16):1912-1915.46936 - Rezk NL, White N, Bridges AS, et al. Studies on antiretroviral drug concentrations in breast milk: validation of a liquid chromatography-tandem mass spectrometric method for determination of 7 anti-human immunodeficiency virus medications. Ther Drug Monit 2008;30(5):611-619.47165 - Norvir (ritonavir tablets, solution, and powder) package insert. North Chicago, IL: AbbVie Inc; 2019 Dec.51080 - Kaletra (lopinavir; ritonavir) capsule package insert. North Chicago, IL: AbbVie Inc; 2019 Aug.56592 - van Noord C, Eijgelsheim M, Stricker BH. Drug- and non-drug-associated QT interval prolongation. Br J Clin Pharmacol 2010;70(1):16-23.65170 - Giudicessi JR, Noseworthy PA, Friedman PA, Ackerman MJ. Urgent guidance for navigating and circumventing the QTc prolonging and torsadogenic potential of possible pharmacotherapies for COVID-19 [published online ahead of print, March 25, 2020]. Mayo Clin Proc 2020;95.65180 - Woosley RL, Heise CW, Gallo T, et al. QTFactors List. Oro Valley, AZ: AZCERT, Inc.; Accessed March 31, 2020. Available on the World Wide Web at: https://crediblemeds.org/ndfa-list/

Mechanism of Action

Lopinavir 400 mg; ritonavir 100 mg given twice daily yields mean steady-state lopinavir plasma concentrations 15- to 20-fold higher than those of ritonavir, with plasma levels of ritonavir less than 7% of those obtained after administration of ritonavir 600 mg twice daily. The in vitro antiviral EC50 (the mean 50% effective concentration) of lopinavir is approximately 10-fold lower than that of ritonavir. Therefore, the antiviral activity of lopinavir; ritonavir is due to lopinavir. Lopinavir is a competitive inhibitor of HIV protease, an enzyme involved in the replication of HIV. During the later stages of the HIV growth cycle, the gag and gag-pol gene products are first translated into polyproteins and become immature budding particles. Protease is responsible for cleaving these precursor molecules to produce the final structural proteins of a mature virion core and to activate reverse transcriptase for a new round of infection. Thus, protease is necessary for the production of mature virions. Protease inhibition renders the virus noninfectious. Because HIV protease inhibitors inhibit the HIV replication cycle after translation and before assembly, they are active in acutely and chronically infected cells, and in cells not normally affected by dideoxynucleoside reverse transcriptase inhibitors (i.e., monocytes and macrophages).[28341][53123]

 

The selection of resistance to lopinavir; ritonavir in treatment-naive patients has not yet been characterized. The presence of ritonavir does not appear to influence the selection of lopinavir-resistant viruses in vitro. Resistance to lopinavir; ritonavir has been noted in patients who were previously treated with protease inhibitors. In 4 patients with mutations associated with protease inhibitor resistance prior to treatment with lopinavir; ritonavir, additional mutations were noted following viral rebound. Some of these mutations were recognized to be associated with protease inhibitor resistance. In vitro, isolates that displayed greater than 4-fold reduced susceptibility to nelfinavir and saquinavir displayed less than 4-fold reduced susceptibility to lopinavir. Isolates with greater than 4-fold reduced susceptibility to indinavir and ritonavir displayed a mean of 5.7- and 8.3-fold reduced susceptibility to lopinavir, respectively. Virologic response to lopinavir; ritonavir is affected by the presence of 3 or more of the following amino acid substitution in protease at baseline: L10F/I/R/V, K20M/N/R, L24I, L33F, M36I, I47V, G48V, I54L/T/V, V82A/C/F/S/T, and I84V.[28341]

 

Lopinavir and ritonavir may bind to Mpro, a key enzyme for coronavirus replication. This may suppress coronavirus activity.[65167]

Revision Date: 03/25/2020, 01:18:25 PM

References

28341 - Kaletra (lopinavir; ritonavir) tablet and solution package insert. North Chicago, IL: AbbVie Inc; 2020 Mar.53123 - Corbett AH, Lim ML, Kashuba ADM. Kaletra (lopinavir/ritonavir). Ann Pharmacother 2002;36:1193-203.65167 - Liu X, Wang XJ. Potential inhibitors for 2019-nCoV coronavirus M protease from clinically proven medicines. J Genet Genomics. 2020.

Pharmacokinetics

Lopinavir; ritonavir is administered orally. Lopinavir is approximately 98% protein bound to alpha1-acid glycoprotein and albumin, with a greater affinity for alpha1-acid glycoprotein. It undergoes oxidative metabolism via the hepatic cytochrome CYP450 system, almost exclusively by the CYP3A isozyme. Ritonavir inhibits CYP3A, thereby increasing plasma concentrations of lopinavir. At least 13 lopinavir oxidative metabolites have been identified in humans. Ritonavir has been shown to induce its own metabolism. Trough lopinavir concentrations decline with time during multiple dosing stabilizing after approximately 10 to 16 days. The half-life of lopinavir is 6.9 +/- 2.2 hours. The majority of lopinavir is excreted as metabolites in the feces (82%), with about 10% of the dose appearing in the urine.[28341] [51080]

 

Affected cytochrome P450 isoenzymes and drug transporters: CYP3A4, CYP2D6, CYP1A2, CYP2C9, CYP2C19, CYP2B6, Organic Anion Transporting Polypeptide 1B1 (OATP1B1), P-glycoprotein (P-gp), glucuronosyl transferase (UGT)

When given as single agents, lopinavir is a substrate of CYP3A4 and an inhibitor of the drug transporter OATP1B1.[28341] [56579] Ritonavir is a substrate, inducer, and potent inhibitor of CYP3A4 (in vivo and in vitro), a partial substrate and minor inhibitor of CYP2D6, and a substrate and inhibitor of P-gp. Ritonavir also appears to induce CYP1A2 and UGT. According to the manufacturer, ritonavir may induce CYP2C9, CYP2C19, and CYP2B6. Ritonavir has been associated with many clinically significant drug interactions; however, the magnitude and effect of ritonavir on the pharmacokinetics of coadministered drugs are difficult to predict due to various CYP enzymes that are affected and the potential of ritonavir to induce or inhibit these enzymes. Interactions with drugs that are substrates of multiple CYP enzymes or that have a low intrinsic CYP3A clearance are especially difficult to predict. Drugs metabolized by CYP3A4 are expected to have large (greater than 3-fold) increases in the AUC when coadministered with ritonavir; drugs metabolized by CYP2D6 may display up to a 2-fold increase in AUC when coadministered with treatment doses of ritonavir. However, according to the manufacturer of lopinavir; ritonavir, the booster dose of ritonavir used in the combination product is unlikely to cause inhibition of CYP2D6.[26120] [27493] [28315] [28341] [28380] [34557] [47165]

Route-Specific Pharmacokinetics

Oral Route

Lopinavir; ritonavir tablets were compared to the original capsule formulation, which is no longer available. Similar lopinavir and ritonavir plasma concentrations are seen following the administration of 2 lopinavir; ritonavir tablets (200 mg; 50 mg each) compared to lopinavir; ritonavir capsules (133.3 mg; 33.3 mg each) under fed conditions; however, less pharmacokinetic variability was seen following the administration of the tablets. In patients with HIV, 400 mg/100 mg lopinavir; ritonavir administered twice daily yields the mean lopinavir Cmax of 9.8 +/- 3.7 mcg/mL approximately 4 hours after administration. In comparison, once-daily dosing of 800 mg/200 mg yields the mean lopinavir Cmax of 11.8 +/- 3.7 mcg/mL. The lopinavir AUC over a 24-hour dosing interval is approximately 1.5-times that seen with a 12-hour dosing interval (154.1 +/- 61.4 mcg x hour/mL vs. 92.6 +/- 36.7 mcg x hour/mL, respectively). Also, once-daily administration of lopinavir; ritonavir yields trough concentrations that are approximately 60% of the concentrations achieved after twice-daily administration (1.7 +/- 1.6 mcg/mL vs. 5.5 +/- 2.7 mcg/mL respectively).[28341]

Relative to fasting, the administration of lopinavir; ritonavir oral solution with a meal increases lopinavir AUC by 130%. To enhance bioavailability and minimize pharmacokinetic variability, lopinavir; ritonavir oral solution should be administered with food. Relative to fasting, administration of lopinavir; ritonavir tablets with a meal increases lopinavir AUC by 19%. These pharmacokinetic alterations were not found to be clinically relevant, and lopinavir; ritonavir tablets may be taken with or without food.[28341]

Special Populations

Hepatic Impairment

Lopinavir is extensively metabolized by the liver; hepatic dysfunction alters the pharmacokinetic parameters of lopinavir; ritonavir. In 1 small study, multiple doses of 400 mg/100 mg lopinavir; ritonavir were given twice daily to HIV and HCV coinfected patients with mild to moderate hepatic impairment (n = 12). An evaluation of the data found the AUC and Cmax of lopinavir to be increased by 30% and 20%, respectively, compared to patients with HIV and normal hepatic function (n = 12). Additionally, the plasma protein binding of lopinavir was significantly lower in both mild and moderate hepatic impairment compared to controls (99.09% vs. 99.31%, respectively). Lopinavir; ritonavir has not been studied in patients with severe hepatic impairment.[28341]

Renal Impairment

Pharmacokinetics of lopinavir; ritonavir are not altered in patients with renal dysfunction. Lopinavir pharmacokinetics have not been studied in patients with renal impairment, although no change in total clearance of lopinavir is expected in patients with renal dysfunction.[28341]

Pediatrics

Infants 6 to 11 months, Children, and Adolescents

The clearance of lopinavir; ritonavir is higher in younger children and decreases with increasing age.[53197] Children have a lower drug exposure of lopinavir; ritonavir compared with adults when treated with doses that are directly scaled for body surface areas (BSA). The directly scaled dose of 230 mg/57.5 mg/m2 of lopinavir; ritonavir would be comparable to the adult dose of 400 mg/100 mg; however, younger children have increased lopinavir clearance and higher doses of the drug would be needed to achieve drug exposures similar to adults with standard dosing. The pediatric dose needs to be increased by 30% to achieve similar trough concentrations compared to those observed in adults.[42452] In a study of pediatric patients ranging in age from 6 months to 12 years, the mean lopinavir trough concentration was 4.74 +/- 2.93 mcg/mL for doses of 230 mg/57.4 mg/m2 (n = 12), while the mean trough concentration was 7.91 +/- 4.52 mcg/mL for doses of 300 mg/75 mg/m2 (n = 15) compared to the adult value of 7.1 +/- 4.52 mcg/mL.[28341][42452][53193] In a study of 23 children, aged 4.8 months to 13 years treated with lopinavir; ritonavir 230 mg/57.5 mg/m2, the mean AUC and Cmin were lower than those observed in adults treated with doses of 400 mg/100 mg. Additionally, a Cmin of less than 1 mg/L was noted in 7 patients (5 patients younger than 2 years and 2 patients older than 2 years, p = 0.011). Lower age was significantly correlated with a lower Cmin (p = 0.003) and AUC (p = 0.009).[42452][53194] The mean half-life reported in studies was 5.8 to 7.6 hours.[53193][53194]

 

Neonates and Infants 1 to 5 months

The clearance of lopinavir; ritonavir is dependent on weight and postmenstrual age in neonates and infants and decreases with increasing age.[53195][53197] The pharmacokinetics of the oral solution at a dose of approximately 300 mg/75 mg/m2 twice daily have been evaluated in infants 14 days and older to younger than 6 weeks of age (n = 9) and between 6 weeks and 6 months of age (n = 18). The mean steady-state lopinavir AUC, Cmax, and trough were 43.4 +/- 14.8 mcg x hour/mL, 5.2 +/- 1.8 mcg/mL, and 2.5 mcg/mL, respectively, in neonates and infants 14 days and older and younger than 6 weeks of age. The mean half-life was 3.67 +/- 1.46 hours. The mean lopinavir AUC, Cmax, and trough were 74.5 +/- 37.9 mcg x hour/mL, 9.4 +/- 4.9 mcg/mL, and 2.7 mcg/mL, respectively, in infants between 6 weeks and 6 months of age. The mean half-life was 4.24 +/- 2.83 hours.[28341][42452][53195][53196]

Other

Pregnancy

Administration of standard dose of lopinavir; ritonavir to women during the second and third trimesters of pregnancy results in reduced systemic drug exposure (AUC). In 1 study involving 17 pregnant women with HIV in their third trimester, standard lopinavir; ritonavir dosing resulted in AUC values that were 46% lower than those observed in the nonpregnant control group. Another study, a population pharmacokinetic model, found systemic clearance of lopinavir increased by 38% early in the second trimester. Based on these data, HIV guidelines suggest the use of higher doses (i.e., 600 mg lopinavir; 150 mg ritonavir) given twice daily during the second and third trimesters. If standard dosing is used, closely monitor virologic response and lopinavir drug concentrations (if available). Avoid the use of the once-daily dosing regimen throughout pregnancy as no pharmacokinetic data are available. Lopinavir; ritonavir has low placental transfer to the fetus.[23512] [60126]

Revision Date: 07/23/2020, 09:55:31 AM

References

23512 - Panel on Treatment of Pregnant Women with HIV infection and Prevention of Perinatal Transmission. Department of Health and Human Services. Recommendations for the use of antiretroviral drugs in pregnant women with HIV infection and interventions to reduce perinatal HIV transmission in the United States. Available at https://aidsinfo.nih.gov/guidelines. Accessed Dec 19, 2019.26120 - Hsu A, Granneman GR, Cao G, et al. Pharmacokinetic interaction between ritonavir and indinavir in healthy volunteers. Antimicrob Agents Chemother 1998;42:2784-91.27493 - Piscitelli SC, Gallicano KD. Interactions among drugs for HIV and opportunistic infections. N Engl J Med 2001;344:984-96.28315 - Norvir (ritonavir capsules) package insert. North Chicago, IL: AbbVie Inc; 2019 Dec.28341 - Kaletra (lopinavir; ritonavir) tablet and solution package insert. North Chicago, IL: AbbVie Inc; 2020 Mar.28380 - Phillips E, Rachlis A, Ito S. Digoxin toxicity and ritonavir: a drug interaction mediated through p-glycoprotein? AIDS 2003;17:1577-8.34557 - Lee CG, Gottesman MM, Cardarelli CO. HIV-1 protease inhibitors are substrates for the MDR1 multidrug transporter. Biochemistry 1998;37:3594-601.42452 - Panel on Antiretroviral Therapy and Medical Management of HIV-infected Children. Guidelines for the use of antiretroviral agents in pediatric HIV infection. Available at https://files.aidsinfo.nih.gov/contentfiles/lvguidelines/PediatricGuidelines.pdf. Accessed May 11, 2020.47165 - Norvir (ritonavir tablets, solution, and powder) package insert. North Chicago, IL: AbbVie Inc; 2019 Dec.51080 - Kaletra (lopinavir; ritonavir) capsule package insert. North Chicago, IL: AbbVie Inc; 2019 Aug.53193 - Saez-Llorens X, Violari A, Deetz CO, et al. Forty-eight week evaluation of lopinavir/ritonavir, a new protease inhibitor, in human immunodeficiency virus-infected children. Pediatr Infect Dis J 2003;22:216-23.53194 - Verweel G, Burger DM, Sheehan NL, et al. Plasma concentrations of the HIV-protease inhibitor lopinavir are suboptimal in children aged 2 years and below. Antivir Ther 2007;12:453-8.53195 - Chadwick EG, Pinto J, Yogev R, et al. Early initiation of lopinavir/ritonavir in infants less than 6 weeks of age: pharmacokinetics and 24 week safety and efficacy. Pediatr Infect Dis J 2009;28:215-9.53196 - Chadwick EG, Capparelli EV, Yogev R, et al. Pharmacokinetics, safety and efficacy of lopinavir/ritonavir in infants less than 6 months of age: 24 week results. AIDS 2008;22:249-55.53197 - Urien S, Firtion G, Anderseon ST, et al. Lopinavir/ritonavir population pharmacokinetics in neonates and infants. Br J Clin Pharmacol 2011;71:956-60.56579 - Drug Development and Drug Interactions: Table of Substrates, Inhibitors and Inducers. Updated Mar 10, 2020. Retrieved from the World Wide Web at www.fda.gov/Drugs/DevelopmentApprovalProcess/DevelopmentResources/DrugInteractionsLabeling/ucm093664.htm60126 - Gilbert EM, Darin KM, Scarsi KK, McLaughlin MM. Antiretroviral pharmacokinetics in pregnant women. Pharmacotherapy 2015;35(9):838-855.

Pregnancy/Breast-feeding

pregnancy

Antiretroviral therapy should be provided to all women during pregnancy, regardless of HIV RNA concentrations or CD4 cell count. Using highly active antiretroviral combination therapy (HAART) to maximally suppress viral replication is the most effective strategy to prevent the development of resistance and to minimize the risk of perinatal transmission. In treatment-naive women, begin HAART as soon as pregnancy is recognized or HIV is diagnosed, without waiting for the results of resistance testing; subsequent modifications to the treatment regimen should be made once the test results are available. Women who are currently receiving antiretroviral treatment when pregnancy is recognized should continue their treatment regimen if it is currently effective in suppressing viral replication; consider resistance testing if HIV RNA concentrations are more than 500 copies/mL. For women not currently receiving HAART, but who have previously received treatment, obtain a complete and accurate history of all prior antiretroviral regimens used and results of prior resistance testing, and perform resistance testing if HIV RNA concentrations are more than 500 copies/mL; treatment should be initiated prior to receiving resistance test results. Available data from the Antiretroviral Pregnancy Registry, which includes more than 1,400 1st trimester exposures to lopinavir-containing regimens, have shown no difference in the risk of overall major birth defects when compared to the 2.7% background rate among pregnant women in the US. When lopinavir; ritonavir exposures occurred in the 1st trimester, the prevalence of defects was 2.1% (30 out of 1,418 births; 95% CI: 1.4, 3.0). Administer lopinavir; ritonavir twice daily in pregnant patients with no documented lopinavir-associated resistance substitutions; there are insufficient data to recommend dosing for pregnant patients with any documented lopinavir-associated resistance substitutions. Once daily lopinavir; ritonavir dosing is NOT recommended in pregnancy. No dosing adjustment is required for patients during the postpartum period. Avoid use of lopinavir; ritonavir oral solution during pregnancy due to the alcohol content.[28341] [47165] Regular laboratory monitoring is recommended to determine antiretroviral efficacy. Monitor CD4 counts at the initial visit and at least every 3 months during pregnancy; consideration may be given to monitoring every 6 months in patients on HAART with consistently suppressed viral loads and a CD4 count well above the opportunistic infection threshold. Monitor plasma HIV RNA at the initial visit, 2 to 4 weeks after initiating or changing therapy, monthly until undetectable, then at least every 3 months during pregnancy, and at 34 to 36 weeks gestation. Perform antiretroviral resistance assay (genotypic testing) at baseline in all women with HIV RNA concentrations greater than 500 copies/mL, unless they have already been tested for resistance. First-trimester ultrasound is recommended to confirm gestational age and provide an accurate estimation of gestational age at deliver. A second-trimester ultrasound can be used for both anatomical survey and determination of gestational age in those patients not seen until later in gestation. Perform standard glucose screening in women receiving antiretroviral therapy at 24 to 28 weeks gestation, although it should be noted that some experts would perform earlier screening with ongoing chronic protease inhibitor-based therapy initiated prior to pregnancy, similar to recommendations for women with high-risk factors for glucose intolerance. All pregnant women should be counseled about the importance of adherence to their antiretroviral regimen to reduce the potential for development of resistance and perinatal transmission. It is strongly recommended that antiretroviral therapy, once initiated, not be discontinued. If a woman decides to discontinue therapy, a consultation with an HIV specialist is recommended. It is strongly recommended that health care providers report cases of antenatal antiretroviral drug exposure to the Antiretroviral Pregnancy Registry; telephone 800-258-4263; fax 800-800-1052; the Antiretroviral Pregnancy Registry is also accessible via the Internet.[23512] [27468] [28341]

breast-feeding

To reduce the risk of postnatal transmission, mothers with HIV within the United States are advised by the Centers for Disease Control and Prevention to avoid breast-feeding. This recommendation applies to both untreated women and women who are receiving antiretroviral therapy. If a mother with HIV opts to breast-feed, the infant should undergo immediate diagnostic and virologic HIV testing. Testing should continue throughout breast-feeding and up to 6 months after cessation of breast-feeding. For expert consultation, health care workers may contact the Perinatal HIV Hotline (888-448-8765).[42452] There are limited data regarding lopinavir; ritonavir use of during breast-feeding, and excretion into human breast milk is unknown. In 1 study, breast milk from mothers receiving lopinavir; ritonavir were analyzed with high-performance liquid chromatography and tandem mass spectrometry; the analysis failed to detect either drug in any of the 60 samples. Antiretroviral medications whose passage into human breast milk have been evaluated include nevirapine, zidovudine, lamivudine, and nelfinavir.[28341] [46936] [46675] [46679] [46680] [46682]

Revision Date: 07/17/2020, 01:25:32 PM

References

23512 - Panel on Treatment of Pregnant Women with HIV infection and Prevention of Perinatal Transmission. Department of Health and Human Services. Recommendations for the use of antiretroviral drugs in pregnant women with HIV infection and interventions to reduce perinatal HIV transmission in the United States. Available at https://aidsinfo.nih.gov/guidelines. Accessed Dec 19, 2019.27468 - APR Steering Committee and Advisory Committee. The Antiretroviral Pregnancy Registry (The Antiretroviral Pregnancy Registry is a collaboration of product manufacturers managed by PharmaResearch Corporation). Issued December 2013. Retrieved April 2, 2014. Available on the World Wide Web at: www.apregistry.com.28341 - Kaletra (lopinavir; ritonavir) tablet and solution package insert. North Chicago, IL: AbbVie Inc; 2020 Mar.42452 - Panel on Antiretroviral Therapy and Medical Management of HIV-infected Children. Guidelines for the use of antiretroviral agents in pediatric HIV infection. Available at https://files.aidsinfo.nih.gov/contentfiles/lvguidelines/PediatricGuidelines.pdf. Accessed May 11, 2020.46638 - Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the use of antiretroviral agents in adults and adolescents with HIV. Department of Health and Human Services. Available at https://aidsinfo.nih.gov/guidelines. Accessed Dec 19, 2019.46675 - Centers for Disease Control and Prevention: Breastfeeding recommendation for human immunodeficiency virus (HIV), and acquired immunodeficiency virus (AIDS). Retrieved November 9, 2011. Available on the World Wide Web at: http://www.cdc.gov/breastfeeding/disease/hiv.htm.46679 - Musoke P, Guay LA, Bagenda D, et al. A phase I/II study of the safety and pharmacokinetics of nevirapine in HIV-1-infected pregnant Ugandan women and their neonates (HIVNET 006). AIDS 1999;13(4):479-486.46680 - Moodley J, Moodley D, Pillay K, et al. Pharmacokinetics and antiretroviral activity of lamivudine alone or when coadministered with zidovudine in human immunodeficiency virus type-1-infected pregnant women and their offspring. J Infec Dis 1998;178:1327-1333.46682 - Colebunders R, Hodossy B, Burger D, et al. The effect of highly active antiretroviral treatment on viral load and antiretroviral drug levels in breast milk. AIDS 2005;19(16):1912-1915.46936 - Rezk NL, White N, Bridges AS, et al. Studies on antiretroviral drug concentrations in breast milk: validation of a liquid chromatography-tandem mass spectrometric method for determination of 7 anti-human immunodeficiency virus medications. Ther Drug Monit 2008;30(5):611-619.47165 - Norvir (ritonavir tablets, solution, and powder) package insert. North Chicago, IL: AbbVie Inc; 2019 Dec.

Interactions

Level 1 (Severe)

  • Alfuzosin
  • Apalutamide
  • Atazanavir; Cobicistat
  • Belladonna Alkaloids; Ergotamine; Phenobarbital
  • Bepridil
  • Caffeine; Ergotamine
  • Cisapride
  • Cobicistat
  • Conivaptan
  • Darunavir; Cobicistat
  • Darunavir; Cobicistat; Emtricitabine; Tenofovir alafenamide
  • Dihydroergotamine
  • Dronedarone
  • Elagolix
  • Elagolix; Estradiol; Norethindrone acetate
  • Elbasvir; Grazoprevir
  • Eletriptan
  • Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Alafenamide
  • Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Disoproxil Fumarate
  • Enzalutamide
  • Eplerenone
  • Ergoloid Mesylates
  • Ergonovine
  • Ergot alkaloids
  • Ergotamine
  • Ezetimibe; Simvastatin
  • Flibanserin
  • Idelalisib
  • Isavuconazonium
  • Isoniazid, INH; Pyrazinamide, PZA; Rifampin
  • Isoniazid, INH; Rifampin
  • Ivabradine
  • Lomitapide
  • Lovastatin
  • Lovastatin; Niacin
  • Lurasidone
  • Meperidine
  • Meperidine; Promethazine
  • Methylergonovine
  • Methysergide
  • Mitotane
  • Naloxegol
  • Niacin; Simvastatin
  • Pergolide
  • Pimozide
  • Ranolazine
  • Red Yeast Rice
  • Rifampin
  • Silodosin
  • Simvastatin
  • Simvastatin; Sitagliptin
  • St. John's Wort, Hypericum perforatum
  • Terfenadine
  • Thioridazine
  • Tolvaptan
  • Triazolam
  • Ubrogepant

Level 2 (Major)

  • Abemaciclib
  • Acalabrutinib
  • Acetaminophen; Butalbital
  • Acetaminophen; Butalbital; Caffeine
  • Acetaminophen; Butalbital; Caffeine; Codeine
  • Acetaminophen; Tramadol
  • Aclidinium; Formoterol
  • Adefovir
  • Ado-Trastuzumab emtansine
  • Albuterol
  • Albuterol; Ipratropium
  • Almotriptan
  • Alosetron
  • Alprazolam
  • Amiodarone
  • Amitriptyline; Chlordiazepoxide
  • Amlodipine; Atorvastatin
  • Amobarbital
  • Amoxapine
  • Amoxicillin; Clarithromycin; Lansoprazole
  • Amoxicillin; Clarithromycin; Omeprazole
  • Anagrelide
  • Apixaban
  • Apomorphine
  • Aprepitant, Fosaprepitant
  • Arformoterol
  • Aripiprazole
  • Armodafinil
  • Arsenic Trioxide
  • Artemether; Lumefantrine
  • Asenapine
  • Aspirin, ASA; Butalbital; Caffeine
  • Aspirin, ASA; Butalbital; Caffeine; Codeine
  • Atomoxetine
  • Atorvastatin
  • Atorvastatin; Ezetimibe
  • Atropine; Hyoscyamine; Phenobarbital; Scopolamine
  • Avanafil
  • Avapritinib
  • Avatrombopag
  • Axitinib
  • Azelastine; Fluticasone
  • Azithromycin
  • Barbiturates
  • Bedaquiline
  • Betrixaban
  • Bismuth Subcitrate Potassium; Metronidazole; Tetracycline
  • Bismuth Subsalicylate; Metronidazole; Tetracycline
  • Boceprevir
  • Bosentan
  • Bosutinib
  • Brexpiprazole
  • Brigatinib
  • Bromocriptine
  • Budesonide
  • Budesonide; Formoterol
  • Budesonide; Glycopyrrolate; Formoterol
  • Buprenorphine
  • Buprenorphine; Naloxone
  • Buspirone
  • Butabarbital
  • Cabazitaxel
  • Cabozantinib
  • Calcium, Magnesium, Potassium, Sodium Oxybates
  • Carbamazepine
  • Cariprazine
  • Ceritinib
  • Cevimeline
  • Chlordiazepoxide
  • Chlordiazepoxide; Clidinium
  • Chloroquine
  • Chlorpromazine
  • Cilostazol
  • Ciprofloxacin
  • Citalopram
  • Clarithromycin
  • Clofazimine
  • Clopidogrel
  • Clorazepate
  • Clozapine
  • Cobimetinib
  • Codeine; Phenylephrine; Promethazine
  • Codeine; Promethazine
  • Colchicine
  • Colchicine; Probenecid
  • Conjugated Estrogens; Medroxyprogesterone
  • Copanlisib
  • Crizotinib
  • Cyclosporine
  • Dabrafenib
  • Daclatasvir
  • Dapagliflozin; Saxagliptin
  • Darunavir
  • Dasabuvir; Ombitasvir; Paritaprevir; Ritonavir
  • Dasatinib
  • Deferasirox
  • Deflazacort
  • Degarelix
  • Delavirdine
  • Deutetrabenazine
  • Dextromethorphan; Promethazine
  • Dextromethorphan; Quinidine
  • Diazepam
  • Digoxin
  • Diltiazem
  • Disopyramide
  • Disulfiram
  • Docetaxel
  • Dofetilide
  • Dolasetron
  • Dolutegravir; Rilpivirine
  • Donepezil
  • Donepezil; Memantine
  • Doxorubicin
  • Doxorubicin Liposomal
  • Dronabinol
  • Droperidol
  • Drospirenone; Ethinyl Estradiol
  • Drospirenone; Ethinyl Estradiol; Levomefolate
  • Dutasteride; Tamsulosin
  • Duvelisib
  • Efavirenz
  • Efavirenz; Emtricitabine; Tenofovir
  • Efavirenz; Lamivudine; Tenofovir Disoproxil Fumarate
  • Elexacaftor; tezacaftor; ivacaftor
  • Eliglustat
  • Eluxadoline
  • Emtricitabine; Rilpivirine; Tenofovir alafenamide
  • Emtricitabine; Rilpivirine; Tenofovir disoproxil fumarate
  • Encainide
  • Encorafenib
  • Entrectinib
  • Erdafitinib
  • Eribulin
  • Erlotinib
  • Erythromycin
  • Erythromycin; Sulfisoxazole
  • Escitalopram
  • Eslicarbazepine
  • Estradiol Cypionate; Medroxyprogesterone
  • Estradiol; Levonorgestrel
  • Eszopiclone
  • Ethanol
  • Ethinyl Estradiol
  • Ethinyl Estradiol; Desogestrel
  • Ethinyl Estradiol; Ethynodiol Diacetate
  • Ethinyl Estradiol; Etonogestrel
  • Ethinyl Estradiol; Levonorgestrel
  • Ethinyl Estradiol; Levonorgestrel; Ferrous bisglycinate
  • Ethinyl Estradiol; Levonorgestrel; Folic Acid; Levomefolate
  • Ethinyl Estradiol; Norelgestromin
  • Ethinyl Estradiol; Norethindrone
  • Ethinyl Estradiol; Norethindrone Acetate
  • Ethinyl Estradiol; Norethindrone Acetate; Ferrous fumarate
  • Ethinyl Estradiol; Norethindrone; Ferrous fumarate
  • Ethinyl Estradiol; Norgestimate
  • Ethinyl Estradiol; Norgestrel
  • Ethotoin
  • Etonogestrel
  • Everolimus
  • Ezogabine
  • Fedratinib
  • Felbamate
  • Fentanyl
  • Fingolimod
  • Flecainide
  • Fluconazole
  • Fluoxetine
  • Fluoxetine; Olanzapine
  • Fluphenazine
  • Flurazepam
  • Fluticasone
  • Fluticasone; Salmeterol
  • Fluticasone; Umeclidinium; Vilanterol
  • Fluticasone; Vilanterol
  • Fluvoxamine
  • Formoterol
  • Formoterol; Mometasone
  • Fosamprenavir
  • Foscarnet
  • Fosphenytoin
  • Fostemsavir
  • Gemifloxacin
  • Gemtuzumab Ozogamicin
  • Gilteritinib
  • Glasdegib
  • Glecaprevir; Pibrentasvir
  • Glycopyrrolate; Formoterol
  • Goserelin
  • Granisetron
  • Griseofulvin
  • Guanfacine
  • Halogenated Anesthetics
  • Haloperidol
  • Histrelin
  • Hydantoins
  • Hydroxychloroquine
  • Hydroxyzine
  • Ibrutinib
  • Ibutilide
  • Iloperidone
  • Imatinib
  • Indacaterol
  • Indacaterol; Glycopyrrolate
  • Inotuzumab Ozogamicin
  • Interferon Alfa-2b; Ribavirin
  • Irinotecan
  • Irinotecan Liposomal
  • Istradefylline
  • Itraconazole
  • Ivacaftor
  • Ivosidenib
  • Ixabepilone
  • Ketoconazole
  • Lamotrigine
  • Lanthanum Carbonate
  • Lapatinib
  • Larotrectinib
  • Lefamulin
  • Lemborexant
  • Lenvatinib
  • Leuprolide
  • Leuprolide; Norethindrone
  • Levalbuterol
  • Levofloxacin
  • Levomethadyl
  • Levomilnacipran
  • Levonorgestrel
  • Lithium
  • Lofexidine
  • Long-acting beta-agonists
  • Loperamide
  • Loperamide; Simethicone
  • Lorlatinib
  • Lumacaftor; Ivacaftor
  • Lumacaftor; Ivacaftor
  • Lumateperone
  • Lurbinectedin
  • Macimorelin
  • Macitentan
  • Maprotiline
  • Maraviroc
  • Medroxyprogesterone
  • Mefloquine
  • Mephobarbital
  • Mesoridazine
  • Mestranol; Norethindrone
  • Metaproterenol
  • Metformin; Saxagliptin
  • Methadone
  • Methohexital
  • Metronidazole
  • Mexiletine
  • Midazolam
  • Midostaurin
  • Mifepristone
  • Mirtazapine
  • Modafinil
  • Moxifloxacin
  • Nafcillin
  • Naldemedine
  • Nefazodone
  • Nelfinavir
  • Neratinib
  • Nevirapine
  • Nifedipine
  • Nilotinib
  • Norfloxacin
  • Octreotide
  • Ofloxacin
  • Olanzapine
  • Olaparib
  • Olodaterol
  • Ombitasvir; Paritaprevir; Ritonavir
  • Omeprazole; Amoxicillin; Rifabutin
  • Ondansetron
  • Oritavancin
  • Orlistat
  • Osilodrostat
  • Osimertinib
  • Ospemifene
  • Oxaliplatin
  • Oxcarbazepine
  • Ozanimod
  • Palbociclib
  • Paliperidone
  • Panobinostat
  • Paroxetine
  • Pasireotide
  • Pazopanib
  • Pemigatinib
  • Pentamidine
  • Pentobarbital
  • Perphenazine
  • Perphenazine; Amitriptyline
  • Pexidartinib
  • Phenobarbital
  • Phenylephrine; Promethazine
  • Phenytoin
  • Pimavanserin
  • Pirbuterol
  • Pitolisant
  • Ponatinib
  • Posaconazole
  • Pralsetinib
  • Primaquine
  • Primidone
  • Procainamide
  • Prochlorperazine
  • Promethazine
  • Propafenone
  • Quazepam
  • Quetiapine
  • Quinidine
  • Quinine
  • Regorafenib
  • Revefenacin
  • Ribavirin
  • Ribociclib
  • Ribociclib; Letrozole
  • Rifabutin
  • Rifapentine
  • Rilpivirine
  • Rimegepant
  • Riociguat
  • Risperidone
  • Rivaroxaban
  • Roflumilast
  • Romidepsin
  • Rosuvastatin
  • Ruxolitinib
  • Sacituzumab Govitecan
  • Salmeterol
  • Saquinavir
  • Saxagliptin
  • Secobarbital
  • Segesterone Acetate; Ethinyl Estradiol
  • Selpercatinib
  • Selumetinib
  • Sertraline
  • Short-acting beta-agonists
  • Sildenafil
  • Simeprevir
  • Siponimod
  • Sirolimus
  • Sodium Oxybate
  • Sofosbuvir; Velpatasvir; Voxilaprevir
  • Solifenacin
  • Sonidegib
  • Sorafenib
  • Sotalol
  • Sunitinib
  • Suvorexant
  • Tacrolimus
  • Tadalafil
  • Tamoxifen
  • Tamsulosin
  • Tasimelteon
  • Tazemetostat
  • Telaprevir
  • Telavancin
  • Telithromycin
  • Temsirolimus
  • Terbutaline
  • Tetrabenazine
  • Tezacaftor; Ivacaftor
  • Thiopental
  • Thiotepa
  • Ticagrelor
  • Tinidazole
  • Tiotropium; Olodaterol
  • Tofacitinib
  • Tolterodine
  • Topotecan
  • Toremifene
  • Trabectedin
  • Tramadol
  • Trazodone
  • Triclabendazole
  • Tricyclic antidepressants
  • Trifluoperazine
  • Triptorelin
  • Umeclidinium; Vilanterol
  • Valbenazine
  • Valproic Acid, Divalproex Sodium
  • Vandetanib
  • Vardenafil
  • Vemurafenib
  • Venetoclax
  • Venlafaxine
  • Vilazodone
  • Vinblastine
  • Vincristine
  • Vincristine Liposomal
  • Vorapaxar
  • Voriconazole
  • Vorinostat
  • Voxelotor
  • Zalcitabine, ddC
  • Zanubrutinib
  • Ziprasidone

Level 3 (Moderate)

  • Abacavir
  • Abacavir; Dolutegravir; Lamivudine
  • Abacavir; Lamivudine, 3TC
  • Abacavir; Lamivudine, 3TC; Zidovudine, ZDV
  • Acarbose
  • Acebutolol
  • Acetaminophen
  • Acetaminophen; Aspirin, ASA; Caffeine
  • Acetaminophen; Caffeine
  • Acetaminophen; Caffeine; Dihydrocodeine
  • Acetaminophen; Caffeine; Magnesium Salicylate; Phenyltoloxamine
  • Acetaminophen; Caffeine; Phenyltoloxamine; Salicylamide
  • Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine
  • Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine
  • Acetaminophen; Chlorpheniramine; Phenylephrine; Phenyltoloxamine
  • Acetaminophen; Codeine
  • Acetaminophen; Dextromethorphan
  • Acetaminophen; Dextromethorphan; Doxylamine
  • Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine
  • Acetaminophen; Dextromethorphan; Phenylephrine
  • Acetaminophen; Dextromethorphan; Pseudoephedrine
  • Acetaminophen; Dichloralphenazone; Isometheptene
  • Acetaminophen; Diphenhydramine
  • Acetaminophen; Guaifenesin; Phenylephrine
  • Acetaminophen; Hydrocodone
  • Acetaminophen; Oxycodone
  • Acetaminophen; Pentazocine
  • Acetaminophen; Propoxyphene
  • Acetaminophen; Pseudoephedrine
  • Afatinib
  • Aldesleukin, IL-2
  • Alfentanil
  • Aliskiren
  • Aliskiren; Amlodipine
  • Aliskiren; Amlodipine; Hydrochlorothiazide, HCTZ
  • Aliskiren; Hydrochlorothiazide, HCTZ
  • Aliskiren; Valsartan
  • Alogliptin
  • Alogliptin; Metformin
  • Alogliptin; Pioglitazone
  • Alpha-glucosidase Inhibitors
  • Amitriptyline
  • Amlodipine
  • Amlodipine; Benazepril
  • Amlodipine; Celecoxib
  • Amlodipine; Hydrochlorothiazide, HCTZ; Olmesartan
  • Amlodipine; Hydrochlorothiazide, HCTZ; Valsartan
  • Amlodipine; Olmesartan
  • Amlodipine; Telmisartan
  • Amlodipine; Valsartan
  • Amphetamine
  • Amphetamine; Dextroamphetamine
  • Amphetamines
  • Artesunate
  • Aspirin, ASA; Caffeine; Dihydrocodeine
  • Aspirin, ASA; Carisoprodol; Codeine
  • Aspirin, ASA; Citric Acid; Sodium Bicarbonate
  • Aspirin, ASA; Omeprazole
  • Aspirin, ASA; Oxycodone
  • Atenolol
  • Atenolol; Chlorthalidone
  • Atovaquone
  • Atovaquone; Proguanil
  • Belladonna; Opium
  • Bendroflumethiazide; Nadolol
  • Benzhydrocodone; Acetaminophen
  • Benzphetamine
  • Betamethasone
  • Betaxolol
  • Bexarotene
  • Bictegravir; Emtricitabine; Tenofovir Alafenamide
  • Bisoprolol
  • Bisoprolol; Hydrochlorothiazide, HCTZ
  • Bortezomib
  • Brimonidine; Timolol
  • Brompheniramine; Guaifenesin; Hydrocodone
  • Brompheniramine; Hydrocodone; Pseudoephedrine
  • Bupivacaine; Lidocaine
  • Bupropion
  • Bupropion; Naltrexone
  • Calcifediol
  • Canagliflozin
  • Canagliflozin; Metformin
  • Capmatinib
  • Carbetapentane; Chlorpheniramine
  • Carbetapentane; Chlorpheniramine; Phenylephrine
  • Carbetapentane; Diphenhydramine; Phenylephrine
  • Carbinoxamine; Hydrocodone; Phenylephrine
  • Carbinoxamine; Hydrocodone; Pseudoephedrine
  • Carteolol
  • Carvedilol
  • Cetirizine
  • Cetirizine; Pseudoephedrine
  • Chloramphenicol
  • Chlorpheniramine
  • Chlorpheniramine; Codeine
  • Chlorpheniramine; Dextromethorphan
  • Chlorpheniramine; Dextromethorphan; Phenylephrine
  • Chlorpheniramine; Dihydrocodeine; Phenylephrine
  • Chlorpheniramine; Dihydrocodeine; Pseudoephedrine
  • Chlorpheniramine; Guaifenesin; Hydrocodone; Pseudoephedrine
  • Chlorpheniramine; Hydrocodone
  • Chlorpheniramine; Hydrocodone; Phenylephrine
  • Chlorpheniramine; Hydrocodone; Pseudoephedrine
  • Chlorpheniramine; Phenylephrine
  • Chlorpheniramine; Pseudoephedrine
  • Ciclesonide
  • Cidofovir
  • Cimetidine
  • Cinacalcet
  • Clevidipine
  • Clindamycin
  • Clobazam
  • Clofarabine
  • Clomipramine
  • Clonazepam
  • Cocaine
  • Codeine
  • Codeine; Guaifenesin
  • Conjugated Estrogens
  • Conjugated Estrogens; Bazedoxifene
  • Cyclophosphamide
  • Dabigatran
  • Dapagliflozin
  • Dapagliflozin; Metformin
  • Dapsone
  • Darifenacin
  • Darolutamide
  • Desipramine
  • Dexamethasone
  • Dexlansoprazole
  • Dexmedetomidine
  • Dextroamphetamine
  • Dextromethorphan; Diphenhydramine; Phenylephrine
  • Diclofenac
  • Diclofenac; Misoprostol
  • Dienogest; Estradiol valerate
  • Dihydrocodeine; Guaifenesin; Pseudoephedrine
  • Diphenhydramine
  • Diphenhydramine; Hydrocodone; Phenylephrine
  • Diphenhydramine; Ibuprofen
  • Diphenhydramine; Naproxen
  • Diphenhydramine; Phenylephrine
  • Doravirine; Lamivudine; Tenofovir disoproxil fumarate
  • Dorzolamide; Timolol
  • Doxazosin
  • Doxepin
  • Doxercalciferol
  • Drospirenone; Estradiol
  • Dutasteride
  • Echinacea
  • Edoxaban
  • Eltrombopag
  • Elvitegravir
  • Empagliflozin
  • Empagliflozin; Linagliptin
  • Empagliflozin; Linagliptin; Metformin
  • Empagliflozin; Metformin
  • Emtricitabine; Tenofovir alafenamide
  • Emtricitabine; Tenofovir disoproxil fumarate
  • Enalapril; Felodipine
  • Enfortumab vedotin
  • Ertugliflozin; Metformin
  • Esmolol
  • Esomeprazole
  • Esomeprazole; Naproxen
  • Estazolam
  • Esterified Estrogens
  • Esterified Estrogens; Methyltestosterone
  • Estradiol
  • Estradiol; Norethindrone
  • Estradiol; Norgestimate
  • Estradiol; Progesterone
  • Estropipate
  • Ethosuximide
  • Etravirine
  • Felodipine
  • Fesoterodine
  • Fexofenadine
  • Fexofenadine; Pseudoephedrine
  • Fluvastatin
  • food
  • Fostamatinib
  • Gefitinib
  • Glipizide; Metformin
  • Glyburide; Metformin
  • grapefruit juice
  • Guaifenesin; Hydrocodone
  • Guaifenesin; Hydrocodone; Pseudoephedrine
  • Halofantrine
  • Homatropine; Hydrocodone
  • Hydrochlorothiazide, HCTZ; Losartan
  • Hydrochlorothiazide, HCTZ; Metoprolol
  • Hydrochlorothiazide, HCTZ; Propranolol
  • Hydrochlorothiazide, HCTZ; Valsartan
  • Hydrocodone
  • Hydrocodone; Ibuprofen
  • Hydrocodone; Phenylephrine
  • Hydrocodone; Potassium Guaiacolsulfonate
  • Hydrocodone; Potassium Guaiacolsulfonate; Pseudoephedrine
  • Hydrocodone; Pseudoephedrine
  • Ibuprofen; Oxycodone
  • Ifosfamide
  • Imipramine
  • Incretin Mimetics
  • Indinavir
  • Insulins
  • Interferons
  • Isradipine
  • Ketamine
  • Labetalol
  • Lacosamide
  • Lamivudine; Tenofovir Disoproxil Fumarate
  • Lansoprazole
  • Lansoprazole; Naproxen
  • Ledipasvir; Sofosbuvir
  • Lesinurad
  • Lesinurad; Allopurinol
  • Letermovir
  • Levamlodipine
  • Levocetirizine
  • Levorphanol
  • Lidocaine
  • Lidocaine; Prilocaine
  • Linagliptin
  • Linagliptin; Metformin
  • Lisdexamfetamine
  • Losartan
  • Meclizine
  • Meloxicam
  • Metformin
  • Metformin; Pioglitazone
  • Metformin; Repaglinide
  • Metformin; Rosiglitazone
  • Metformin; Sitagliptin
  • Methamphetamine
  • Methylprednisolone
  • Metoclopramide
  • Metoprolol
  • Miglitol
  • Mirabegron
  • Mometasone
  • Morphine
  • Morphine; Naltrexone
  • Nabilone
  • Nadolol
  • Nanoparticle Albumin-Bound Paclitaxel
  • Nateglinide
  • Nebivolol
  • Nebivolol; Valsartan
  • Netupitant, Fosnetupitant; Palonosetron
  • Nicardipine
  • Nimodipine
  • Nintedanib
  • Nisoldipine
  • Norethindrone
  • Nortriptyline
  • Omeprazole
  • Omeprazole; Sodium Bicarbonate
  • Oxybutynin
  • Oxycodone
  • Oxymorphone
  • Paricalcitol
  • Penbutolol
  • Perampanel
  • Perindopril; Amlodipine
  • Phentermine; Topiramate
  • Pindolol
  • Pirfenidone
  • Polatuzumab Vedotin
  • Pomalidomide
  • Pramlintide
  • Praziquantel
  • Prednisolone
  • Prednisone
  • Progesterone
  • Propofol
  • Propoxyphene
  • Propranolol
  • Protriptyline
  • Ramelteon
  • Remifentanil
  • Repaglinide
  • Retapamulin
  • Rifaximin
  • Riluzole
  • Ripretinib
  • Rocuronium
  • Sacubitril; Valsartan
  • Sapropterin
  • Selexipag
  • Sibutramine
  • Sitagliptin
  • Sodium Bicarbonate
  • Sufentanil
  • Sulfonylureas
  • Talazoparib
  • Telotristat Ethyl
  • Teniposide
  • Tenofovir Alafenamide
  • Tenofovir Alafenamide
  • Tenofovir, PMPA
  • Terbinafine
  • Testosterone
  • Theophylline, Aminophylline
  • Thiazolidinediones
  • Tiagabine
  • Timolol
  • Topiramate
  • Trandolapril; Verapamil
  • Triamcinolone
  • Trimetrexate
  • Trimipramine
  • Tucatinib
  • Ulipristal
  • Upadacitinib
  • Valsartan
  • Verapamil
  • Vinorelbine
  • Warfarin
  • Yohimbine
  • Zafirlukast
  • Zaleplon
  • Zileuton
  • Zolmitriptan
  • Zolpidem
  • Zonisamide

Level 4 (Minor)

  • Atazanavir
  • Brentuximab vedotin
  • Bupivacaine
  • Bupivacaine Liposomal
  • Doravirine
  • Lamivudine, 3TC; Zidovudine, ZDV
  • Levobupivacaine
  • Paclitaxel
  • Rabeprazole
  • Tesamorelin
  • Zidovudine, ZDV
Abacavir: (Moderate) Caution is advised when administering abacavir and ritonavir concurrently. Ritonavir appears to induce glucuronosyl transferase, and therefore, has the potential to reduce plasma concentrations of drugs that undergo glucuronidation, such as abacavir. The clinical significance of the potential for this interaction is unknown. [28341] [47165] Abacavir; Dolutegravir; Lamivudine: (Moderate) Caution is advised when administering abacavir and ritonavir concurrently. Ritonavir appears to induce glucuronosyl transferase, and therefore, has the potential to reduce plasma concentrations of drugs that undergo glucuronidation, such as abacavir. The clinical significance of the potential for this interaction is unknown. [28341] [47165] Abacavir; Lamivudine, 3TC: (Moderate) Caution is advised when administering abacavir and ritonavir concurrently. Ritonavir appears to induce glucuronosyl transferase, and therefore, has the potential to reduce plasma concentrations of drugs that undergo glucuronidation, such as abacavir. The clinical significance of the potential for this interaction is unknown. [28341] [47165] Abacavir; Lamivudine, 3TC; Zidovudine, ZDV: (Moderate) Caution is advised when administering abacavir and ritonavir concurrently. Ritonavir appears to induce glucuronosyl transferase, and therefore, has the potential to reduce plasma concentrations of drugs that undergo glucuronidation, such as abacavir. The clinical significance of the potential for this interaction is unknown. [28341] [47165] (Minor) Since ritonavir induces glucuronidation, there is the potential for reduction in zidovudine, ZDV plasma concentrations during concurrent therapy with ritonavir. When coadministered with ritonavir, the AUC and Cmax of zidovudine, ZDV are decreased by 12% and 27%. The clinical significance of this interaction is unknown. [28315] [47165] [58664] Abemaciclib: (Major) If coadministration with ritonavir is necessary, reduce the dose of abemaciclib to 100 mg PO twice daily in patients on either of the recommended starting doses of either 200 mg or 150 mg twice daily. In patients who have had already had a dose reduction to 100 mg twice daily due to adverse reactions, further reduce the dose of abemaciclib to 50 mg PO twice daily. Discontinue abemaciclib for patients unable to tolerate 50 mg twice daily. If ritonavir is discontinued, increase the dose of abemaciclib to the original dose after 3 to 5 half-lives of ritonavir. Abemaciclib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the relative potency adjusted unbound AUC of abemaciclib plus its active metabolites (M2, M18, and M20) by 2.5-fold in cancer patients. [47165] [62393] Acalabrutinib: (Major) Avoid the concomitant use of acalabrutinib and ritonavir; significantly increased acalabrutinib exposure may occur. Acalabrutinib is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. In healthy subjects, the Cmax and AUC values of acalabrutinib were increased by 3.9-fold and 5.1-fold, respectively, when acalabrutinib was coadministered with another strong inhibitor for 5 days. [47165] [62578] Acarbose: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. [7238] [7335] Acebutolol: (Moderate) Cardiac and neurologic events have been reported when ritonavir was concurrently administered with beta-blockers. [5044] Acetaminophen: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Aspirin, ASA; Caffeine: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Butalbital: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Butalbital; Caffeine: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Butalbital; Caffeine; Codeine: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] (Moderate) Concomitant use of codeine with ritonavir may alter codeine plasma concentrations, resulting in an unpredictable effect such as reduced efficacy or symptoms of opioid withdrawal or prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage adjustment of codeine until stable drug effects are achieved. Discontinuation of ritonavir could alter codeine plasma concentrations, resulting in an unpredictable effect such as prolonged opioid adverse reactions or decreased opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If ritonavir is discontinued, monitor the patient carefully and consider adjusting the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Ritonavir is a strong inhibitor of CYP3A4 and a weak inhibitor of CYP2D6. CYP3A4 inhibitors may increase codeine-related adverse effects while CYP2D6 inhibitors may reduce efficacy. [33654] [34883] [47165] (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Caffeine: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Caffeine; Dihydrocodeine: (Moderate) Concomitant use of dihydrocodeine with ritonavir may increase dihydrocodeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased dihydromorphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of dihydrocodeine until stable drug effects are achieved. Discontinuation of ritonavir could decrease dihydrocodeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to dihydrocodeine. If ritonavir is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Ritonavir is a strong inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of dihydrocodeine. [30282] [47165] (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Caffeine; Magnesium Salicylate; Phenyltoloxamine: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Caffeine; Phenyltoloxamine; Salicylamide: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] Acetaminophen; Chlorpheniramine; Phenylephrine; Phenyltoloxamine: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] Acetaminophen; Codeine: (Moderate) Concomitant use of codeine with ritonavir may alter codeine plasma concentrations, resulting in an unpredictable effect such as reduced efficacy or symptoms of opioid withdrawal or prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage adjustment of codeine until stable drug effects are achieved. Discontinuation of ritonavir could alter codeine plasma concentrations, resulting in an unpredictable effect such as prolonged opioid adverse reactions or decreased opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If ritonavir is discontinued, monitor the patient carefully and consider adjusting the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Ritonavir is a strong inhibitor of CYP3A4 and a weak inhibitor of CYP2D6. CYP3A4 inhibitors may increase codeine-related adverse effects while CYP2D6 inhibitors may reduce efficacy. [33654] [34883] [47165] (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Dextromethorphan: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Dextromethorphan; Doxylamine: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Dextromethorphan; Phenylephrine: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Dextromethorphan; Pseudoephedrine: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Dichloralphenazone; Isometheptene: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Diphenhydramine: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] (Moderate) Concurrent administration of diphenhydramine with ritonavir may result in elevated plasma concentrations of diphenhydramine. Diphenhydramine is a CYP2D6 substrate, and ritonavir is a CYP2D6 inhibitor. Caution and close monitoring are advised if these drugs are administered together. [34522] [34523] [47165] [58664] Acetaminophen; Guaifenesin; Phenylephrine: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Hydrocodone: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Acetaminophen; Oxycodone: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] (Moderate) Consider a reduced dose of oxycodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. If ritonavir is discontinued, consider increasing the oxycodone dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oxycodone is a CYP3A4 substrate, and coadministration with a strong CYP3A4 inhibitor like ritonavir can increase oxycodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of oxycodone. If ritonavir is discontinued, oxycodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to oxycodone. [39926] [47165] Acetaminophen; Pentazocine: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Propoxyphene: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] (Moderate) Due to effects on microsomal isoenzymes responsible for hepatic metabolism, ritonavir may alter the response and/or increase the AUC of opiate analgesics. Concurrent use of ritonavir and propoxyphene is not recommended, due the increased formation of the neurotoxic metabolites of propoxyphene. Also, propoxyphene is a substrate/inhibitor of CYP3A4. Increased serum concentrations of propoxyphene can occur from concurrent use of ritonavir, a CYP3A4 inhibitor. A reduced dosage of propoxyphene may be needed. Monitor for CNS and respiratory depression. [11379] [36008] [4718] [5044] Acetaminophen; Pseudoephedrine: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Acetaminophen; Tramadol: (Major) Tramadol is primarily metabolized by CYP2D6 and CYP3A4; drugs that inhibit these enzymes, such as ritonavir, may decrease the metabolism of tramadol. This may result in a decreased concentration of the active metabolite (O-desmethyltramadol) leading to decreased analgesic effects and possibly increased side effects (seizures and serotonin syndrome) due to higher tramadol concentrations. [40255] [5043] [9316] (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] Aclidinium; Formoterol: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] Adefovir: (Major) Patients who are concurrently taking adefovir with antiretrovirals like the protease inhibitors, are at risk of developing lactic acidosis and severe hepatomegaly with steatosis. Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogs alone or in combination with antiretrovirals. A majority of these cases have been in women; obesity and prolonged nucleoside exposure may also be risk factors. Particular caution should be exercised when administering nucleoside analogs to any patient with known risk factors for hepatic disease; however, cases have also been reported in patients with no known risk factors. Suspend adefovir in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity (which may include hepatomegaly and steatosis even in the absence of marked transaminase elevations). [28784] Ado-Trastuzumab emtansine: (Major) Avoid coadministration of ritonavir with ado-trastuzumab emtansine if possible due to the risk of elevated exposure to the cytotoxic component of ado-trastuzumab emtansine, DM1. Delay ado-trastuzumab emtansine treatment until ritonavir has cleared from the circulation (approximately 3 half-lives of ritonavir) when possible. If concomitant use is unavoidable, closely monitor patients for ado-trastuzumab emtansine-related adverse reactions. The cytotoxic component of ado-trastuzumab emtansine, DM1, is metabolized mainly by CYP3A4 and to a lesser extent by CYP3A5; ritonavir is a strong CYP3A4 inhibitor. Formal drug interaction studies with ado-trastuzumab emtansine have not been conducted. [28315] [53295] Afatinib: (Moderate) If the concomitant use of ritonavir and afatinib is necessary, monitor for afatinib-related adverse reactions. If the original dose of afatinib is not tolerated, consider reducing the daily dose of afatinib by 10 mg; resume the previous dose of afatinib as tolerated after discontinuation of ritonavir. The manufacturer of afatinib recommends permanent discontinuation of therapy for severe or intolerant adverse drug reactions at a dose of 20 mg per day, but does not address a minimum dose otherwise. Afatinib is a P-glycoprotein (P-gp) substrate and ritonavir is a P-gp inhibitor; coadministration may increase plasma concentrations of afatinib. Administration with another P-gp inhibitor, given 1 hour before a single dose of afatinib, increased afatinib exposure by 48%; there was no change in afatinib exposure when the P-gp inhibitor was administered at the same time as afatinib or 6 hours later. In healthy subjects, the relative bioavailability for AUC and Cmax of afatinib was 119% and 104%, respectively, when coadministered with the same P-gp inhibitor, and 111% and 105% when the inhibitor was administered 6 hours after afatinib. [28315] [55331] Albuterol: (Major) Avoid coadministration of lopinavir with short-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28341] [33925] [65157] [65170] Albuterol; Ipratropium: (Major) Avoid coadministration of lopinavir with short-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28341] [33925] [65157] [65170] Aldesleukin, IL-2: (Moderate) Concurrent administration of aldesleukin, IL-2 with ritonavir may result in increased plasma concentrations of ritonavir. Aldesleukin, IL-2 increases IL-6 concentrations, and IL-6 is an inhibitor of the hepatic isoenzyme CYP3A4; ritonavir is a substrate of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [2356] [34540] [58664] Alfentanil: (Moderate) Alfentanil is metabolized by the hepatic isoenzyme CYP3A4. Drugs that inhibit this enzyme, such as protease inhibitors, may alter responses to alfentanil. A dose reduction of one or both drugs may be warranted. Monitor closely for oversedation and respiratory depression. [28001] [28995] [47165] Alfuzosin: (Severe) Coadministration of alfuzosin with protease inhibitors is contraindicated due to potential hypotension. Alfuzosin is a CYP3A4 substrate and protease inhibitors are strong CYP3A4 inhibitors. [28261] [28341] Aliskiren: (Moderate) The plasma concentrations of aliskiren may be elevated when administered concurrently with ritonavir. Clinical monitoring for adverse effects, such as decreased blood pressure, is recommended during coadministration. Ritonavir is an inhibitor of CYP3A4 and P-glycoprotein (P-gp). Aliskiren is a substrate of both CYP3A4 and P-gp. [33200] [47165] [56579] Aliskiren; Amlodipine: (Moderate) Amlodipine is a CYP3A4 substrate. Theoretically, CYP3A4 inhibitors, such as anti-retroviral protease inhibitors, may increase the plasma concentration of amlodipine via CYP3A4 inhibition; this effect might lead to hypotension in some individuals. Caution should be used when anti-retroviral protease inhibitors are coadministered with amlodipine; therapeutic response should be monitored. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [29090] [47165] [58664] (Moderate) The plasma concentrations of aliskiren may be elevated when administered concurrently with ritonavir. Clinical monitoring for adverse effects, such as decreased blood pressure, is recommended during coadministration. Ritonavir is an inhibitor of CYP3A4 and P-glycoprotein (P-gp). Aliskiren is a substrate of both CYP3A4 and P-gp. [33200] [47165] [56579] Aliskiren; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Amlodipine is a CYP3A4 substrate. Theoretically, CYP3A4 inhibitors, such as anti-retroviral protease inhibitors, may increase the plasma concentration of amlodipine via CYP3A4 inhibition; this effect might lead to hypotension in some individuals. Caution should be used when anti-retroviral protease inhibitors are coadministered with amlodipine; therapeutic response should be monitored. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [29090] [47165] [58664] (Moderate) The plasma concentrations of aliskiren may be elevated when administered concurrently with ritonavir. Clinical monitoring for adverse effects, such as decreased blood pressure, is recommended during coadministration. Ritonavir is an inhibitor of CYP3A4 and P-glycoprotein (P-gp). Aliskiren is a substrate of both CYP3A4 and P-gp. [33200] [47165] [56579] Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) The plasma concentrations of aliskiren may be elevated when administered concurrently with ritonavir. Clinical monitoring for adverse effects, such as decreased blood pressure, is recommended during coadministration. Ritonavir is an inhibitor of CYP3A4 and P-glycoprotein (P-gp). Aliskiren is a substrate of both CYP3A4 and P-gp. [33200] [47165] [56579] Aliskiren; Valsartan: (Moderate) Concurrent use of lopinavir with valsartan may result in elevated valsartan serum concentrations. Valsartan is a substrate for the drug transporter organic anion transporting polypeptide (OATP1B1/1B3); lopinavir is an OATP1B1 inhibitor. Monitor for increased toxicities if these drugs are given together. [56579] [61510] [61511] [61513] (Moderate) The plasma concentrations of aliskiren may be elevated when administered concurrently with ritonavir. Clinical monitoring for adverse effects, such as decreased blood pressure, is recommended during coadministration. Ritonavir is an inhibitor of CYP3A4 and P-glycoprotein (P-gp). Aliskiren is a substrate of both CYP3A4 and P-gp. [33200] [47165] [56579] (Minor) Valsartan is a substrate of the hepatic efflux transporter MRP2 and ritonavir is an inhibitor of MRP2. Coadministration may increase systemic exposure to valsartan. Patients should be monitored for adverse effects of valsartan during coadministration. [28315] [29130] [36646] [39870] [60860] Almotriptan: (Major) Ritonavir may increase the systemic exposure of almotriptan. If coadministered, the recommended starting dose of almotriptan is 6.25 mg; do not exceed 12.5 mg within a 24-hour period. Avoid coadministration in patients with renal or hepatic impairment. Almotriptan is a CYP3A4 substrate and ritonavir is a potent CYP3A4 inhibitor. In a drug interaction study, coadministration of almotriptan and ketoconazole, another potent CYP3A4 inhibitor, resulted in an approximately 60% increase in almotriptan exposure. [28001] [31869] Alogliptin: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [7238] [7335] Alogliptin; Metformin: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [7238] [7335] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30480] [30575] Alogliptin; Pioglitazone: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [7238] [7335] Alosetron: (Major) Concurrent administration of alosetron with ritonavir may alter alosetron plasma concentrations; however, the precise effect is undefined. Alosetron is metabolized by the hepatic isoenzymes CYP3A4, CYP2C9, and CYP1A2; ritonavir is an inhibitor of CYP3A4 and an inducer of CYP1A2 and possibly CYP2C9. Caution and close monitoring are advised if these drugs are administered together. [28382] [5044] Alpha-glucosidase Inhibitors: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. [7238] [7335] Alprazolam: (Major) Coadministration of alprazolam and ritonavir is not recommended. If coadministration cannot be avoided, a dosage reduction of alprazolam should be considered. Ritonavir is a potent CYP3A4 inhibitor. The initial step in alprazolam metabolism is hydroxylation catalyzed by cytochrome CYP3A. Drugs that inhibit this metabolic pathway may profoundly decrease alprazolam clearance, resulting in increased potential for serious alprazolam-related adverse events, such as respiratory depression and prolonged sedation. Consequently, alprazolam should be avoided in patients receiving very potent inhibitors of CYP3A isoenzymes. [28040] [28341] [47165] Amiodarone: (Major) Avoid coadministration of lopinavir with amiodarone due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Amiodarone, a Class III antiarrhythmic agent, is associated with a well-established risk of QT prolongation and torsade de pointes (TdP). Although the frequency of TdP is less with amiodarone than with other Class III agents, amiodarone is still associated with a risk of TdP. Due to the extremely long half-life of amiodarone, a drug interaction is possible for days to weeks after discontinuation of amiodarone. [28224] [28341] [28432] [28457] [65157] [65170] (Major) Coadministration of HIV treatment doses of ritonavir and amiodarone is contraindicated due to the potential for serious or life-threatening reactions, such as cardiac arrhythmias. Cautious consideration may be given to administering amiodarone with boosting doses of ritonavir. Ritonavir is an inhibitor of CYP3A4 and increased plasma concentrations of drugs extensively metabolized by this enzyme, such as amiodarone, should be expected with concurrent use. [47165] Amitriptyline: (Moderate) A dose reduction of the tricyclic antidepressant (TCA) may be necessary when coadministered with ritonavir. Concurrent use may result in elevated TCA plasma concentrations. [47165] Amitriptyline; Chlordiazepoxide: (Major) CYP3A4 inhibitors, such as protease inhibitors, may reduce the metabolism of chlordiazepoxide and increase the potential for benzodiazepine toxicity. A decrease in the chlordiazepoxide dose may be needed. [32432] [5286] (Moderate) A dose reduction of the tricyclic antidepressant (TCA) may be necessary when coadministered with ritonavir. Concurrent use may result in elevated TCA plasma concentrations. [47165] Amlodipine: (Moderate) Amlodipine is a CYP3A4 substrate. Theoretically, CYP3A4 inhibitors, such as anti-retroviral protease inhibitors, may increase the plasma concentration of amlodipine via CYP3A4 inhibition; this effect might lead to hypotension in some individuals. Caution should be used when anti-retroviral protease inhibitors are coadministered with amlodipine; therapeutic response should be monitored. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [29090] [47165] [58664] Amlodipine; Atorvastatin: (Major) Use caution and the lowest atorvastatin dose necessary if atorvastatin must be coadministered with ritonavir. The risk of developing myopathy/rhabdomyolysis increases when atorvastatin is used concomitantly with ritonavir. Monitor patients for any signs or symptoms of muscle pain, weakness, or tenderness especially in the initial months of therapy and any time the dosage of either drug is titrated upward. Protease inhibitors inhibit the CYP3A4 metabolism of atorvastatin. The serious risk of myopathy or rhabdomyolysis should be weighed carefully against the benefits of combined 'statin' and lopinavir; ritonavir therapy; there is no assurance that periodic monitoring of CK will prevent the occurrence of severe myopathy and renal damage. [43900] (Major) Use caution and the lowest atorvastatin dose necessary if coadministration with lopinavir is necessary due to an increased risk of myopathy and rhabdomyolysis. Closely monitor patients for signs and symptoms of muscle pain, tenderness, or weakness especially during the initial months of therapy and during upward titration of either drug. There is no assurance that period monitoring of creatinine phosphokinase (CPK) will prevent the occurrence of myopathy. Atorvastatin is a substrate of the drug transporter organic anion transporting polypeptide (OATP1B1); lopinavir is an OATP1B1 inhibitor. [28341] [28729] [34503] [41275] [61510] [61511] [61513] (Moderate) Amlodipine is a CYP3A4 substrate. Theoretically, CYP3A4 inhibitors, such as anti-retroviral protease inhibitors, may increase the plasma concentration of amlodipine via CYP3A4 inhibition; this effect might lead to hypotension in some individuals. Caution should be used when anti-retroviral protease inhibitors are coadministered with amlodipine; therapeutic response should be monitored. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [29090] [47165] [58664] Amlodipine; Benazepril: (Moderate) Amlodipine is a CYP3A4 substrate. Theoretically, CYP3A4 inhibitors, such as anti-retroviral protease inhibitors, may increase the plasma concentration of amlodipine via CYP3A4 inhibition; this effect might lead to hypotension in some individuals. Caution should be used when anti-retroviral protease inhibitors are coadministered with amlodipine; therapeutic response should be monitored. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [29090] [47165] [58664] Amlodipine; Celecoxib: (Moderate) Amlodipine is a CYP3A4 substrate. Theoretically, CYP3A4 inhibitors, such as anti-retroviral protease inhibitors, may increase the plasma concentration of amlodipine via CYP3A4 inhibition; this effect might lead to hypotension in some individuals. Caution should be used when anti-retroviral protease inhibitors are coadministered with amlodipine; therapeutic response should be monitored. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [29090] [47165] [58664] Amlodipine; Hydrochlorothiazide, HCTZ; Olmesartan: (Moderate) Amlodipine is a CYP3A4 substrate. Theoretically, CYP3A4 inhibitors, such as anti-retroviral protease inhibitors, may increase the plasma concentration of amlodipine via CYP3A4 inhibition; this effect might lead to hypotension in some individuals. Caution should be used when anti-retroviral protease inhibitors are coadministered with amlodipine; therapeutic response should be monitored. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [29090] [47165] [58664] Amlodipine; Hydrochlorothiazide, HCTZ; Valsartan: (Moderate) Amlodipine is a CYP3A4 substrate. Theoretically, CYP3A4 inhibitors, such as anti-retroviral protease inhibitors, may increase the plasma concentration of amlodipine via CYP3A4 inhibition; this effect might lead to hypotension in some individuals. Caution should be used when anti-retroviral protease inhibitors are coadministered with amlodipine; therapeutic response should be monitored. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [29090] [47165] [58664] (Moderate) Concurrent use of lopinavir with valsartan may result in elevated valsartan serum concentrations. Valsartan is a substrate for the drug transporter organic anion transporting polypeptide (OATP1B1/1B3); lopinavir is an OATP1B1 inhibitor. Monitor for increased toxicities if these drugs are given together. [56579] [61510] [61511] [61513] (Minor) Valsartan is a substrate of the hepatic efflux transporter MRP2 and ritonavir is an inhibitor of MRP2. Coadministration may increase systemic exposure to valsartan. Patients should be monitored for adverse effects of valsartan during coadministration. [28315] [29130] [36646] [39870] [60860] Amlodipine; Olmesartan: (Moderate) Amlodipine is a CYP3A4 substrate. Theoretically, CYP3A4 inhibitors, such as anti-retroviral protease inhibitors, may increase the plasma concentration of amlodipine via CYP3A4 inhibition; this effect might lead to hypotension in some individuals. Caution should be used when anti-retroviral protease inhibitors are coadministered with amlodipine; therapeutic response should be monitored. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [29090] [47165] [58664] Amlodipine; Telmisartan: (Moderate) Amlodipine is a CYP3A4 substrate. Theoretically, CYP3A4 inhibitors, such as anti-retroviral protease inhibitors, may increase the plasma concentration of amlodipine via CYP3A4 inhibition; this effect might lead to hypotension in some individuals. Caution should be used when anti-retroviral protease inhibitors are coadministered with amlodipine; therapeutic response should be monitored. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [29090] [47165] [58664] Amlodipine; Valsartan: (Moderate) Amlodipine is a CYP3A4 substrate. Theoretically, CYP3A4 inhibitors, such as anti-retroviral protease inhibitors, may increase the plasma concentration of amlodipine via CYP3A4 inhibition; this effect might lead to hypotension in some individuals. Caution should be used when anti-retroviral protease inhibitors are coadministered with amlodipine; therapeutic response should be monitored. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [29090] [47165] [58664] (Moderate) Concurrent use of lopinavir with valsartan may result in elevated valsartan serum concentrations. Valsartan is a substrate for the drug transporter organic anion transporting polypeptide (OATP1B1/1B3); lopinavir is an OATP1B1 inhibitor. Monitor for increased toxicities if these drugs are given together. [56579] [61510] [61511] [61513] (Minor) Valsartan is a substrate of the hepatic efflux transporter MRP2 and ritonavir is an inhibitor of MRP2. Coadministration may increase systemic exposure to valsartan. Patients should be monitored for adverse effects of valsartan during coadministration. [28315] [29130] [36646] [39870] [60860] Amobarbital: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] Amoxapine: (Major) Ritonavir potently inhibits CYP2D6, and may inhibit the metabolism of amoxapine. Since the magnitude of the interaction with the amoxapine is difficult to predict but may be significant, monitor patients receiving ritonavir and amoxapine concurrently closely. Adjust the dosage of the coadministered drug based on therapeutic response. Amoxapine serum concentration monitoring may be useful to guide adjustments and prevent toxicity. [28558] [46638] [47165] Amoxicillin; Clarithromycin; Lansoprazole: (Major) Avoid coadministration of lopinavir with clarithromycin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Clarithromycin is associated with an established risk for QT prolongation and torsade de pointes (TdP). [28225] [28238] [28341] [28413] [28419] [65157] [65170] (Major) Because the exposure to 14-OH clarithromycin is significantly decreased by ritonavir, consider alternative antibiotic therapy for indications other than Mycobacterium avium. Clarithromycin doses above 1000 mg should not be administered with ritonavir. If coadministration cannot be avoided, clarithromycin dosage reductions are recommended in patients with renal impairment (CrCl 30 to 60 mL/minute, decrease clarithromycin by 50%; CrCl less than 30 mL/minute, decrease clarithromycin by 75%). Concomitant administration of ritonavir and clarithromycin resulted in a 77% increase in clarithromycin exposure and a 100% decrease in 14-OH clarithromycin exposure. The microbiological activities of clarithromycin and 14-OH-clarithromycin are different for different bacteria. [28238] [46638] [47165] (Moderate) Increased exposure to lansoprazole may occur during concurrent administration of ritonavir. Although dosage adjustment of lansoprazole is not normally required, dosage reduction may be considered in patients receiving higher lansoprazole doses (e.g., those with Zollinger-Ellison syndrome). Ritonavir is a strong CYP3A4 inhibitor. Lansoprazole is a CYP2C19 and CYP3A4 substrate. Coadministration of a dual CYP2C19/strong CYP3A4 inhibitor increased the lansoprazole AUC by an average of 4-times. [40596] [47165] Amoxicillin; Clarithromycin; Omeprazole: (Major) Avoid coadministration of lopinavir with clarithromycin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Clarithromycin is associated with an established risk for QT prolongation and torsade de pointes (TdP). [28225] [28238] [28341] [28413] [28419] [65157] [65170] (Major) Because the exposure to 14-OH clarithromycin is significantly decreased by ritonavir, consider alternative antibiotic therapy for indications other than Mycobacterium avium. Clarithromycin doses above 1000 mg should not be administered with ritonavir. If coadministration cannot be avoided, clarithromycin dosage reductions are recommended in patients with renal impairment (CrCl 30 to 60 mL/minute, decrease clarithromycin by 50%; CrCl less than 30 mL/minute, decrease clarithromycin by 75%). Concomitant administration of ritonavir and clarithromycin resulted in a 77% increase in clarithromycin exposure and a 100% decrease in 14-OH clarithromycin exposure. The microbiological activities of clarithromycin and 14-OH-clarithromycin are different for different bacteria. [28238] [46638] [47165] (Moderate) Increased exposure to omeprazole may occur during concurrent administration of ritonavir. Although dosage adjustment of omeprazole is not normally required, dosage reduction may be considered in patients receiving higher omeprazole doses (e.g., those with Zollinger-Ellison syndrome). Ritonavir is a strong CYP3A4 inhibitor. Omeprazole is a CYP2C19 and CYP3A4 substrate. Coadministration of a dual CYP2C19/strong CYP3A4 inhibitor increased the omeprazole AUC by an average of 4-times. [29564] [47165] Amphetamine: (Moderate) Warn patients that the risk of amphetamine toxicity may be increased during concurrent use of ritonavir, a strong CYP2D6 inhibitor. Amphetamines are partially metabolized by CYP2D6 and have serotonergic properties; inhibition of amphetamine metabolism may increase the risk of serotonin syndrome or other toxicity. If serotonin syndrome occurs, both the amphetamine and CYP2D6 inhibitor should be discontinued and appropriate medical treatment should be implemented. [25887] [29219] [33263] [47165] [57067] Amphetamine; Dextroamphetamine: (Moderate) Warn patients that the risk of amphetamine toxicity may be increased during concurrent use of ritonavir, a strong CYP2D6 inhibitor. Amphetamines are partially metabolized by CYP2D6 and have serotonergic properties; inhibition of amphetamine metabolism may increase the risk of serotonin syndrome or other toxicity. If serotonin syndrome occurs, both the amphetamine and CYP2D6 inhibitor should be discontinued and appropriate medical treatment should be implemented. [25887] [29219] [33263] [47165] [57067] Amphetamines: (Moderate) Warn patients that the risk of amphetamine toxicity may be increased during concurrent use of ritonavir, a strong CYP2D6 inhibitor. Amphetamines are partially metabolized by CYP2D6 and have serotonergic properties; inhibition of amphetamine metabolism may increase the risk of serotonin syndrome or other toxicity. If serotonin syndrome occurs, both the amphetamine and CYP2D6 inhibitor should be discontinued and appropriate medical treatment should be implemented. [25887] [29219] [33263] [47165] [57067] Anagrelide: (Major) Avoid coadministration of lopinavir with anagrelide due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Torsade de pointes (TdP) and ventricular tachycardia have been reported with anagrelide. In addition, dose-related increases in mean QTc and heart rate were observed in healthy subjects. [28341] [30163] [65157] [65170] Apalutamide: (Severe) Coadministration of lopinavir with apalutamide is contraindicated. Taking these drugs together could decrease lopinavir concentrations, and may lead to a reduction in antiretroviral activity. Lopinavir is a CYP3A4 substrate. Apalutamide is a strong CYP3A4 inducer. [28341] [56579] [62874] (Severe) Coadministration of ritonavir with apalutamide is contraindicated as there is a potential for decreased ritonavir concentrations which may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance; exposure to apalutamide may also increase. Ritonavir is a CYP3A4 substrate and strong inhibitor. Apalutamide is a CYP3A4 substrate and strong inducer. [47165] [62874] Apixaban: (Major) Reduce the apixaban dose by 50% when coadministered with drugs that are both strong inhibitors of CYP3A4 and P-gp, such as ritonavir. If patients are already receiving the reduced dose of 2.5 mg twice daily, avoid concomitant administration of apixaban and ritonavir. Concomitant administration of ritonavir and apixaban results in increased exposure to apixaban and an increase in the risk of bleeding. [52739] Apomorphine: (Major) Avoid coadministration of lopinavir; ritonavir with apomorphine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Dose-related QTc prolongation is associated with therapeutic apomorphine exposure. [28341] [28661] [65157] [65170] Aprepitant, Fosaprepitant: (Major) Avoid the concomitant use of ritonavir with aprepitant, fosaprepitant due to substantially increased exposure of aprepitant; after administration, fosaprepitant is rapidly converted to aprepitant and shares many of the same drug interactions. Increased ritonavir exposure may also occur. If coadministration cannot be avoided, use caution and monitor for an increase in ritonavir- and aprepitant-related adverse effects for several days after administration of a multi-day aprepitant regimen. Ritonavir is a strong CYP3A4 inhibitor and aprepitant is a CYP3A4 substrate. Coadministration with another strong CYP3A4 inhibitor increased the AUC of aprepitant by approximately 5-fold, and the mean terminal half-life by approximately 3-fold. Ritonavir is also a is also a CYP3A4 substrate. Aprepitant, when administered as a 3-day oral regimen (125 mg/80 mg/80 mg), is a moderate CYP3A4 inhibitor. When administered as a single oral or single intravenous dose, the inhibitory effect of aprepitant on CYP3A4 is weak and does not result in a clinically significant increase in the AUC of a sensitive substrate. [30676] [40027] [47165] (Moderate) Concurrent administration of lopinavir and aprepitant, fosaprepitant may result in increased lopinavir exposure. Lopinavir is a CYP3A4 substrate. Aprepitant, when administered as a 3-day oral regimen (125 mg/80 mg/80 mg), is a moderate CYP3A4 inhibitor. However, when administered as a single oral or single intravenous dose, the inhibitory effect of aprepitant on CYP3A4 is weak and does not result in a clinically significant increase in the AUC of a sensitive substrate. [28341] [30676] [40027] [56579] Arformoterol: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] (Moderate) The use of ritonavir could result in QT prolongation. Drugs with a possible risk for QT prolongation and TdP that should be used cautiously and with close monitoring with ritonavir, include beta-agonists. [28318] [33925] [41231] [47165] Aripiprazole: (Major) Avoid coadministration of lopinavir with aripiprazole due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. QT prolongation has occurred during therapeutic use of aripiprazole and following overdose. [28341] [42845] [65157] [65170] (Major) Because aripiprazole is metabolized by CYP3A4 and CYP2D6, the manufacturer recommends that the oral aripiprazole dose be reduced to one-quarter (25%) of the usual dose in patients receiving inhibitors of both CYP3A4 and CYP2D6 such as ritonavir. Patients classified as CYP2D6 poor metabolizers (PMs) who are receiving a strong CYP3A4 inhibitor should have their oral aripiprazole dose reduced to one-quarter (25%) of the usual dose with subsequent adjustments based upon clinical response. Adults receiving a combination of a CYP3A4 and CYP2D6 inhibitor for more than 14 days should have their Abilify Maintena dose reduced from 400 mg/month to 200 mg/month or from 300 mg/month to 160 mg/month, respectively. Adults receiving Abilify Maintena who are PMs and receiving a strong CYP3A4 inhibitor, such as ritonavir, should have a dose reduction to 200 mg/month IM. In adults receiving Aristada, the Aristada dose should be reduced to the next lower strength during use of a strong CYP3A4 inhibitor for more than 14 days. For patients receiving 882 mg of Aristada every 6 weeks or 1064 mg every 2 months, the next lower strength should be 441 mg administered every 4 weeks. No dosage adjustment is necessary in patients taking 441 mg IM of Aristada, if tolerated. Adults receiving Aristada who are PMs of CYP2D6 and receiving a strong CYP3A4 inhibitor for more than 14 days should have their dose reduced from 662 mg, 882 mg, or 1064 mg to 441 mg IM; no dose adjustment is needed in patients receiving 441 mg of Aristada, if tolerated. In adults receiving Aristada 662 mg, 882 mg, or 1064 mg, combined use of a strong CYP2D6 inhibitor and a strong CYP3A4 inhibitor for more than 14 days should be avoided; no dose adjustment is needed in patients taking 441 mg, if tolerated. Avoid concurrent use of Aristada Initio and strong CYP3A4 inhibitors because the dose of Aristada Initio cannot be modified. [28341] [42845] [47165] [53394] [60196] [63328] Armodafinil: (Major) Coadministration of ritonavir with armodafinil may result in elevated armodafinil concentrations and decreased ritonavir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Armodafinil is a substrate and inducer of CYP3A4, and a P-glycoprotein (P-gp) substrate. Ritonavir is a substrate of CYP3A4 and an inhibitor of P-gp. Ritonavir is also a potent inhibitor of CYP3A4. [33467] [47165] Arsenic Trioxide: (Major) Avoid coadministration of lopinavir with arsenic trioxide due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Torsade de pointes (TdP), QT interval prolongation, and complete atrioventricular block have been reported with arsenic trioxide use. [28226] [28341] [28432] [28457] [65157] [65170] Artemether; Lumefantrine: (Major) Avoid coadministration of lopinavir with artemether; lumefantrine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs are associated with QT prolongation. [28341] [35401] [5162] [65157] [65170] (Major) Avoid coadministration of lopinavir with artemether; lumefantrine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs are associated with QT prolongation. [28341] [35401] [65157] [65170] (Major) Ritonavir is a substrate, potent inhibitor, and inducer of the CYP3A4 isoenzyme, depending on the activity of the coadministered drug. Both components of artemether; lumefantrine are substrates of the CYP3A4 isoenzyme; therefore, coadministration may lead to increased or decreased artemether; lumefantrine concentrations. Concomitant use warrants caution due to the potential for increased side effects, including increased potentiation of QT prolongation due to increased drug concentrations, or loss of antimalarial activity depending on the artemether; lumefantrine concentrations. Consider ECG monitoring if ritonavir must be used with or after artemether; lumefantrine treatment. [11416] [35401] [4194] [47165] [5044] [5110] (Major) Ritonavir is a substrate, potent inhibitor, and inducer of the CYP3A4 isoenzyme, depending on the activity of the coadministered drug. Both components of artemether; lumefantrine are substrates of the CYP3A4 isoenzyme; therefore, coadministration may lead to increased or decreased artemether; lumefantrine concentrations. Concomitant use warrants caution due to the potential for increased side effects, including increased potentiation of QT prolongation due to increased drug concentrations, or loss of antimalarial activity depending on the artemether; lumefantrine concentrations. Consider ECG monitoring if ritonavir must be used with or after artemether; lumefantrine treatment. [11416] [35401] [4194] [5044] [5110] [60002] Artesunate: (Moderate) Monitor for a decrease in antimalarial efficacy if artesunate is coadministered with ritonavir. Coadministration of oral artesunate with ritonavir resulted in a decrease in the AUC of the active metabolite of artesunate, dihydroartemisinin, by 38%. [65484] Asenapine: (Major) Avoid coadministration of lopinavir with asenapine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs have been associated with QT prolongation. [28341] [36343] [65157] [65170] Aspirin, ASA; Butalbital; Caffeine: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] Aspirin, ASA; Butalbital; Caffeine; Codeine: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] (Moderate) Concomitant use of codeine with ritonavir may alter codeine plasma concentrations, resulting in an unpredictable effect such as reduced efficacy or symptoms of opioid withdrawal or prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage adjustment of codeine until stable drug effects are achieved. Discontinuation of ritonavir could alter codeine plasma concentrations, resulting in an unpredictable effect such as prolonged opioid adverse reactions or decreased opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If ritonavir is discontinued, monitor the patient carefully and consider adjusting the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Ritonavir is a strong inhibitor of CYP3A4 and a weak inhibitor of CYP2D6. CYP3A4 inhibitors may increase codeine-related adverse effects while CYP2D6 inhibitors may reduce efficacy. [33654] [34883] [47165] Aspirin, ASA; Caffeine; Dihydrocodeine: (Moderate) Concomitant use of dihydrocodeine with ritonavir may increase dihydrocodeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased dihydromorphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of dihydrocodeine until stable drug effects are achieved. Discontinuation of ritonavir could decrease dihydrocodeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to dihydrocodeine. If ritonavir is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Ritonavir is a strong inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of dihydrocodeine. [30282] [47165] Aspirin, ASA; Carisoprodol; Codeine: (Moderate) Concomitant use of codeine with ritonavir may alter codeine plasma concentrations, resulting in an unpredictable effect such as reduced efficacy or symptoms of opioid withdrawal or prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage adjustment of codeine until stable drug effects are achieved. Discontinuation of ritonavir could alter codeine plasma concentrations, resulting in an unpredictable effect such as prolonged opioid adverse reactions or decreased opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If ritonavir is discontinued, monitor the patient carefully and consider adjusting the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Ritonavir is a strong inhibitor of CYP3A4 and a weak inhibitor of CYP2D6. CYP3A4 inhibitors may increase codeine-related adverse effects while CYP2D6 inhibitors may reduce efficacy. [33654] [34883] [47165] Aspirin, ASA; Citric Acid; Sodium Bicarbonate: (Moderate) Concurrent administration of tipranavir and ritonavir with antacids results in decreased tipranavir concentrations. Administer tipranavir and ritonavir 2 hours before or 1 hour after antacids. [1800] [1802] Aspirin, ASA; Omeprazole: (Moderate) Increased exposure to omeprazole may occur during concurrent administration of ritonavir. Although dosage adjustment of omeprazole is not normally required, dosage reduction may be considered in patients receiving higher omeprazole doses (e.g., those with Zollinger-Ellison syndrome). Ritonavir is a strong CYP3A4 inhibitor. Omeprazole is a CYP2C19 and CYP3A4 substrate. Coadministration of a dual CYP2C19/strong CYP3A4 inhibitor increased the omeprazole AUC by an average of 4-times. [29564] [47165] Aspirin, ASA; Oxycodone: (Moderate) Consider a reduced dose of oxycodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. If ritonavir is discontinued, consider increasing the oxycodone dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oxycodone is a CYP3A4 substrate, and coadministration with a strong CYP3A4 inhibitor like ritonavir can increase oxycodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of oxycodone. If ritonavir is discontinued, oxycodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to oxycodone. [39926] [47165] Atazanavir: (Minor) Coadministration of atazanavir with ritonavir results in higher atazanavir concentrations; reduced adult doses of atazanavir 300 mg once daily are recommended when ritonavir (100 mg once daily) is given concomitantly. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including atazanavir) has not been evaluated. Atazanavir is a CYP3A4 substrate; ritonavir is a strong inhibitor of CYP3A4. [28142] [28315] Atazanavir; Cobicistat: (Severe) Use of ritonavir with cobicistat is not recommended, because of similar effects on CYP3A. Both ritonavir and cobicistat are potent inhibitors of CYP3A4. [51664] [58000] [58761] [58763] (Minor) Coadministration of atazanavir with ritonavir results in higher atazanavir concentrations; reduced adult doses of atazanavir 300 mg once daily are recommended when ritonavir (100 mg once daily) is given concomitantly. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including atazanavir) has not been evaluated. Atazanavir is a CYP3A4 substrate; ritonavir is a strong inhibitor of CYP3A4. [28142] [28315] Atenolol: (Moderate) Cardiac and neurologic events have been reported when ritonavir was concurrently administered with beta-blockers. [5044] Atenolol; Chlorthalidone: (Moderate) Cardiac and neurologic events have been reported when ritonavir was concurrently administered with beta-blockers. [5044] Atomoxetine: (Major) Avoid coadministration of lopinavir with atomoxetine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. QT prolongation has occurred during therapeutic use of atomoxetine and following overdose. [28341] [28405] [65157] [65170] Atorvastatin: (Major) Use caution and the lowest atorvastatin dose necessary if atorvastatin must be coadministered with ritonavir. The risk of developing myopathy/rhabdomyolysis increases when atorvastatin is used concomitantly with ritonavir. Monitor patients for any signs or symptoms of muscle pain, weakness, or tenderness especially in the initial months of therapy and any time the dosage of either drug is titrated upward. Protease inhibitors inhibit the CYP3A4 metabolism of atorvastatin. The serious risk of myopathy or rhabdomyolysis should be weighed carefully against the benefits of combined 'statin' and lopinavir; ritonavir therapy; there is no assurance that periodic monitoring of CK will prevent the occurrence of severe myopathy and renal damage. [43900] (Major) Use caution and the lowest atorvastatin dose necessary if coadministration with lopinavir is necessary due to an increased risk of myopathy and rhabdomyolysis. Closely monitor patients for signs and symptoms of muscle pain, tenderness, or weakness especially during the initial months of therapy and during upward titration of either drug. There is no assurance that period monitoring of creatinine phosphokinase (CPK) will prevent the occurrence of myopathy. Atorvastatin is a substrate of the drug transporter organic anion transporting polypeptide (OATP1B1); lopinavir is an OATP1B1 inhibitor. [28341] [28729] [34503] [41275] [61510] [61511] [61513] Atorvastatin; Ezetimibe: (Major) Use caution and the lowest atorvastatin dose necessary if atorvastatin must be coadministered with ritonavir. The risk of developing myopathy/rhabdomyolysis increases when atorvastatin is used concomitantly with ritonavir. Monitor patients for any signs or symptoms of muscle pain, weakness, or tenderness especially in the initial months of therapy and any time the dosage of either drug is titrated upward. Protease inhibitors inhibit the CYP3A4 metabolism of atorvastatin. The serious risk of myopathy or rhabdomyolysis should be weighed carefully against the benefits of combined 'statin' and lopinavir; ritonavir therapy; there is no assurance that periodic monitoring of CK will prevent the occurrence of severe myopathy and renal damage. [43900] (Major) Use caution and the lowest atorvastatin dose necessary if coadministration with lopinavir is necessary due to an increased risk of myopathy and rhabdomyolysis. Closely monitor patients for signs and symptoms of muscle pain, tenderness, or weakness especially during the initial months of therapy and during upward titration of either drug. There is no assurance that period monitoring of creatinine phosphokinase (CPK) will prevent the occurrence of myopathy. Atorvastatin is a substrate of the drug transporter organic anion transporting polypeptide (OATP1B1); lopinavir is an OATP1B1 inhibitor. [28341] [28729] [34503] [41275] [61510] [61511] [61513] Atovaquone: (Moderate) Concurrent administration of lopinavir; ritonavir with atovaquone; proguanil has shown to decrease the atovaquone AUC by 74% and the proguanil AUC by 38%. Consider alternative malaria prophylaxis or antiretroviral therapy. If used together, an increase in the atovaquone dose may be needed. The clinical significance and mechanism of this potential interaction are unknown. [28341] [46638] (Minor) The concurrent administration of ritonavir with atovaquone may result in decreased plasma levels of atovaquone. The clinical significance and mechanism of this potential interaction are unknown; the manufacturer states that an increase in atovaquone doses may be needed. [28315] [28341] [46638] [58664] Atovaquone; Proguanil: (Moderate) Concurrent administration of lopinavir; ritonavir with atovaquone; proguanil has shown to decrease the atovaquone AUC by 74% and the proguanil AUC by 38%. Consider alternative malaria prophylaxis or antiretroviral therapy. If used together, an increase in the atovaquone dose may be needed. The clinical significance and mechanism of this potential interaction are unknown. [28341] [46638] (Minor) The concurrent administration of ritonavir with atovaquone may result in decreased plasma levels of atovaquone. The clinical significance and mechanism of this potential interaction are unknown; the manufacturer states that an increase in atovaquone doses may be needed. [28315] [28341] [46638] [58664] Atropine; Hyoscyamine; Phenobarbital; Scopolamine: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] Avanafil: (Major) Avanafil is a substrate of and primarily metabolized by CYP3A4. Studies have shown that drugs that inhibit CYP3A4 can increase avanafil exposure. Patients taking strong CYP3A4 inhibitors such as ritonavir, should not take avanafil. For example, ketoconazole increased avanafil AUC and Cmax equal to 13-fold and 3-fold, respectively and prolonged the half-life of avanafil to approximately 9 hours. Likewise, coadministration of ritonavir with avanafil resulted in an approximate 13-fold increase in AUC and 2.4-fold increase in Cmax of avanafil. Therefore, concomitant use with strong CYP3A4 inhibitors is not recommended. [28315] [47165] [49866] Avapritinib: (Major) Avoid coadministration of avapritinib with ritonavir due to the risk of increased avapritinib-related adverse reactions. Avapritinib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor is predicted to increase the AUC of avapritinib by 600% at steady-state. [47165] [64922] Avatrombopag: (Major) In patients with chronic immune thrombocytopenia (ITP), increase the starting dose of avatrombopag to 40 mg PO once daily when used concomitantly with ritonavir. In patients starting ritonavir while receiving avatrombopag, monitor platelet counts and adjust the avatrombopag dose as necessary. Dosage adjustments are not required for patients with chronic liver disease. Avatrombopag is a CYP2C9 and CYP3A4 substrate, and dual moderate or strong inducers such as ritonavir decrease avatrombopag exposure, which may reduce efficacy. [47165] [63175] Axitinib: (Major) Avoid coadministration of axitinib with ritonavir due to the risk of increased axitinib-related adverse reactions. If coadministration is unavoidable, decrease the dose of axitinib by approximately half; subsequent doses can be increased or decreased based on individual safety and tolerability. Resume the original dose of axitinib approximately 3 to 5 half-lives after ritonavir is discontinued. Axitinib is a CYP3A4/5 substrate and ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4/5 inhibitor significantly increased the plasma exposure of axitinib in healthy volunteers. [47165] [48494] Azelastine; Fluticasone: (Major) Coadministration of inhaled fluticasone propionate and ritonavir is not recommended; use caution with inhaled fluticasone furoate. During post-marketing use, there have been reports of clinically significant drug interactions in patients receiving inhaled fluticasone propionate with ritonavir, resulting in systemic corticosteroid effects including Cushing's syndrome and adrenal suppression. Fluticasone is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. In a drug interaction study, coadministration with ritonavir increased plasma fluticasone propionate exposure resulting in an 86% decrease in serum cortisol AUC. Another strong inhibitor increased fluticasone furoate exposure by 1.33-fold with a 27% reduction in weighted mean serum cortisol; this change does not necessitate dose adjustment of fluticasone furoate. [40360] [40475] [43972] [57805] Azithromycin: (Major) Avoid coadministration of azithromycin with lopinavir; ritonavir due to the increased risk of QT prolongation. If use together is necessary, obtain an ECG at baseline to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. QT prolongation and torsade de pointes (TdP) have been spontaneously reported during azithromycin postmarketing surveillance. Lopinavir; ritonavir is associated with QT prolongation. [28341] [28855] [43974] [65157] [65170] Barbiturates: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] Bedaquiline: (Major) Avoid coadministration of lopinavir with bedaquiline due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Discontinue bedaquiline if evidence of serious ventricular arrhythmia or QTcF interval more than 500 msec. Both drugs are associated with QT prolongation. [28341] [52746] [65157] [65170] (Major) Concurrent use of bedaquiline and ritonavir should be avoided due to the potential risk of adverse reactions to bedaquiline because of increased systemic exposure. Bedaquiline is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Concurrent use of another strong CYP3A4 inhibitor increased bedaquiline exposure by 22%. [47165] [52746] Belladonna Alkaloids; Ergotamine; Phenobarbital: (Severe) Coadministration of ergot alkaloids with potent inhibitors of CYP3A4, like anti-retroviral protease inhibitors is considered contraindicated due to the risk of acute ergot toxicity (e.g., vasospasm leading to cerebral ischemia, peripheral ischemia and/or other serious effects). Several case reports have established the clinical significance of this interaction in the medical literature. In some cases, fatal interactions have occurred. [28142] [28341] [28731] [28839] [28995] [32432] [46638] [5018] [5044] [5623] [5747] [8102] (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] Belladonna; Opium: (Moderate) Ritonavir is an inhibitor of the cytochrome P450 3A4 isoenzyme and may decrease the metabolism of opium if the two drugs are coadministered. [4718] Bendroflumethiazide; Nadolol: (Moderate) Cardiac and neurologic events have been reported when ritonavir was concurrently administered with beta-blockers. [5044] Benzhydrocodone; Acetaminophen: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [25460] [28100] [58664] (Moderate) Concurrent use of benzhydrocodone with ritonavir may increase the risk of increased opioid-related adverse reactions, such as fatal respiratory depression. Consider a dose reduction of benzhydrocodone until stable drug effects are achieved. Monitor patients for respiratory depression and sedation at frequent intervals. Discontinuation of ritonavir in a patient taking benzhydrocodone may decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to opioid agonists. If ritonavir is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Benzhydrocodone is a prodrug for hydrocodone. Hydrocodone is a substrate for CYP3A4 and CYP2D6. Ritonavir is a strong inhibitor of CYP3A4 and a weak in vitro inhibitor of CYP2D6. [47165] [62889] Benzphetamine: (Moderate) Warn patients that the risk of amphetamine toxicity may be increased during concurrent use of ritonavir, a strong CYP2D6 inhibitor. Amphetamines are partially metabolized by CYP2D6 and have serotonergic properties; inhibition of amphetamine metabolism may increase the risk of serotonin syndrome or other toxicity. If serotonin syndrome occurs, both the amphetamine and CYP2D6 inhibitor should be discontinued and appropriate medical treatment should be implemented. [25887] [29219] [33263] [47165] [57067] Bepridil: (Severe) Ritonavir can produce large increases in plasma concentrations of certain drugs metabolized by cytochrome P450 3A4. The concurrent use of ritonavir is contraindicated with bepridil. [46638] [5044] Betamethasone: (Moderate) Consider an alternative corticosteroid that is less affected by CYP3A4 (i.e., beclomethasone or prednisolone), particularly for long-term use, in patients receiving ritonavir. Coadministration may significantly increase betamethasone exposure increasing the risk for Cushing's syndrome and adrenal suppression. Ritonavir is a strong CYP3A4 inhibitor and betamethasone is a CYP3A4 substrate. Another strong CYP3A4 inhibitor has been reported to decrease the metabolism of certain corticosteroids by up to 60%. [28341] [47165] [63066] Betaxolol: (Moderate) Cardiac and neurologic events have been reported when ritonavir was concurrently administered with beta-blockers. [5044] Betrixaban: (Major) Avoid betrixaban use in patients with severe renal impairment receiving ritonavir. Reduce betrixaban dosage to 80 mg PO once followed by 40 mg PO once daily in all other patients receiving ritonavir. Bleeding risk may be increased; monitor patients closely for signs and symptoms of bleeding. Betrixaban is a substrate of P-gp; ritonavir inhibits P-gp. [28380] [56579] [62037] Bexarotene: (Moderate) Avoid the concomitant use of bexarotene and lopinavir as decreased plasma concentrations of lopinavir may occur resulting in reduced therapeutic effect. Consider alternative therapy. Bexarotene is a moderate CYP3A4 inducer and lopinavir is a CYP3A4 substrate. [28341] [61590] Bictegravir; Emtricitabine; Tenofovir Alafenamide: (Moderate) Concurrent use of lopinavir with tenofovir alafenamide may result in elevated tenofovir serum concentrations. Tenofovir alafenamide is a substrate for the drug transporter organic anion transporting polypeptide (OATP1B1/1B3); lopinavir is an OATP1B1 inhibitor. When 10 mg of tenofovir alafenamide was administered daily with lopinavir; ritonavir (800 mg/200 mg PO daily), the tenofovir Cmax and AUC increased by 2.19-fold and 1.47-fold, respectively. Monitor for increased toxicities if these drugs are given together. [60269] [61510] [61511] [61513] Bismuth Subcitrate Potassium; Metronidazole; Tetracycline: (Major) Avoid coadministration of lopinavir with metronidazole due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Potential QT prolongation has been reported in limited case reports with metronidazole. Additionally, oral solutions of lopinavir; ritonavir contain ethanol which can produce disulfiram-like reactions when coadministered with metronidazole. [28341] [57377] [57378] [65157] [65170] (Major) Medications with significant alcohol content should not be ingested during therapy with metronidazole and should be avoided for 3 days after therapy is discontinued. Ritonavir oral solution and capsules contain ethanol. Administration of ritonavir oral solution or capsules to patients receiving or who have recently received disulfiram or metronidazole may result in disulfiram-like reactions. A disulfiram reaction would not be expected to occur with non-ethanol containing formulations of ritonavir (e.g., tablets, oral powder). [28315] [28581] [47165] Bismuth Subsalicylate; Metronidazole; Tetracycline: (Major) Avoid coadministration of lopinavir with metronidazole due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Potential QT prolongation has been reported in limited case reports with metronidazole. Additionally, oral solutions of lopinavir; ritonavir contain ethanol which can produce disulfiram-like reactions when coadministered with metronidazole. [28341] [57377] [57378] [65157] [65170] (Major) Medications with significant alcohol content should not be ingested during therapy with metronidazole and should be avoided for 3 days after therapy is discontinued. Ritonavir oral solution and capsules contain ethanol. Administration of ritonavir oral solution or capsules to patients receiving or who have recently received disulfiram or metronidazole may result in disulfiram-like reactions. A disulfiram reaction would not be expected to occur with non-ethanol containing formulations of ritonavir (e.g., tablets, oral powder). [28315] [28581] [47165] Bisoprolol: (Moderate) Cardiac and neurologic events have been reported when ritonavir was concurrently administered with beta-blockers. [5044] Bisoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Cardiac and neurologic events have been reported when ritonavir was concurrently administered with beta-blockers. [5044] Boceprevir: (Major) Concurrent administration of lopinavir with boceprevir is not recommended due to the potential for HIV and hepatitis C treatment failures. Use of this combination has resulted in decreased serum concentrations of both drugs. If these drugs are coadministered, health care providers are advised to closely monitor for decreased treatment response and virologic rebound. Health care providers are also encouraged to report any drug-related adverse reactions to the FDA MedWatch Program. [28341] [44314] [48674] [51080] (Major) Concurrent administration of ritonavir with boceprevir is not recommended due to the potential for HIV and hepatitis C treatment failures. This combination has resulted in decreased serum concentrations of both medications. Ritonavir is an inhibitor, inducer, and substrate of the hepatic isoenzyme CYP3A4; boceprevir is an inhibitor and substrate of this isoenzyme. Additionally, both drugs are substrates and inhibitors of the drug efflux transporter P-glycoprotein (PGP). If these drugs are coadministered, health care providers are advised to closely monitor for decreased treatment response and virologic rebound. Health care providers are also encouraged to report any drug-related adverse reactions to the FDA MedWatch Program. [28315] [44314] [48674] Bortezomib: (Moderate) In vitro studies with human liver microsomes indicate that bortezomib is a significant substrate for CYP3A4. Agents that inhibit CYP3A4, such ritonavir, may increase the exposure to bortezomib and increase the risk for toxicity. The manufacturer warns that patients who are receiving bortezomib concurrently with potent CYP3A4 inhibitors should be closely monitored for potential toxicity. Additionally, ritonavir can cause peripheral neuropathy. It may be prudent to monitor patients for signs and symptoms of neuropathy. [28383] Bosentan: (Major) Do not administer bosentan with anti-retroviral protease inhibitors that are not boosted with ritonavir as decreased protease inhibitor concentrations are expected. In addition, administration of anti-retroviral protease inhibitors with bosentan may increase bosentan serum concentrations due to the inhibition of the CYP3A4 isoenzyme. In patients who have been receiving protease inhibitor therapy for at least 10 days, initiate bosentan at the recommended initial dose once daily or every other day based on tolerability. For patients on bosentan who need protease inhibitor therapy, discontinue use of bosentan at least 36 hours prior to starting protease inhibitor therapy. After 10 days of the protease inhibitor therapy, bosentan may be restarted at the recommended initial dose once daily or every other day based on tolerability. Bosentan is a substrate for organic anion transport protein (OATP), CYP3A, and CYP2C9. In healthy subjects, initial and steady state trough plasma concentrations of bosentan were approximately 48-fold and 5-fold higher, respectively, after coadministration of bosentan 125 mg twice daily PO and lopinavir; ritonavir 400/100 mg twice daily PO compared to those measured after bosentan alone. This is most likely explained by inhibition by lopinavir of OATP-mediated uptake into hepatocytes; toxicity of bosentan is possible. Monitor for potential adverse effects of bosentan during coadministration with CYP2C9 or CYP3A4 inhibitors; excessive bosentan dosage may result in hypotension or elevated hepatic enzyme. Additionally, bosentan is a significant inducer of CYP3A4 and CYP2C9 hepatic enzymes. Theoretically, bosentan may increase the clearance of the protease inhibitors and potentially lead to a reduction of anti-retroviral efficacy. However, this interaction has not been studied. [28142] [28315] [28341] [28496] [28731] [28839] [28995] [29012] [31320] [32432] [46638] [56579] [61510] [61511] [61512] [61513] Bosutinib: (Major) Avoid concomitant use of bosutinib and ritonavir or lopinavir; ritonavir as bosutinib plasma exposure may be significantly increased resulting in an increased risk of bosutinib adverse events (e.g., myelosuppression, GI toxicity). Bosutinib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. In a cross-over trial in 24 healthy volunteers, the Cmax and AUC values of bosutinib were increased 5.2-fold and 8.6-fold, respectively, when a single oral dose of bosutinib 100 mg PO was administered after 5 days of a strong CYP3A4 inhibitor. [28315] [51739] Brentuximab vedotin: (Minor) Concomitant administration of brentuximab vedotin and ritonavir may increase the exposure of monomethyl auristatin E (MMAE), one of the 3 components released from brentuximab vedotin. The manufacturer suggests that potent CYP3A4 inhibitors, such as ritonavir, may alter MMAE exposure as MMAE is a CYP3A4 substrate. Monitor patients for adverse reactions. [11416] [45378] [5044] [5110] Brexpiprazole: (Major) Because brexpiprazole is primarily metabolized by CYP3A4 and CYP2D6, the manufacturer recommends that the brexpiprazole dose be reduced to one-quarter (25%) of the usual dose in patients receiving a moderate to strong inhibitor of CYP3A4 inhibitor in combination with a moderate to strong inhibitor of CYP2D6. Ritonavir (including lopinavir; ritonavir) is a strong inhibitor of CYP3A4 and a moderate inhibitor of CYP2D6. If these agents are used in combination, the patient should be carefully monitored for brexpiprazole-related adverse reactions. If the co-administered CYP inhibitor is discontinued, adjust the brexpiprazole dose to its original level. [59949] Brigatinib: (Major) Avoid coadministration of brigatinib with ritonavir if possible due to increased plasma exposure of brigatinib; an increase in brigatinib-related adverse reactions may occur. If concomitant use is unavoidable, reduce the dose of brigatinib by approximately 50% without breaking tablets (i.e., from 180 mg to 90 mg; from 90 mg to 60 mg); after discontinuation of ritonavir, resume the brigatinib dose that was tolerated prior to initiation of ritonavir. Brigatinib is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the AUC and Cmax of brigatinib by 101% and 21%, respectively. [28315] [61909] Brimonidine; Timolol: (Moderate) Timolol is significantly metabolized by CYP2D6 isoenzymes. CYP2D6 inhibitors, such as ritonavir, may impair timolol metabolism; the clinical significance of such interactions is unknown. [5044] [5270] Bromocriptine: (Major) When bromocriptine is used for diabetes, avoid coadministration with ritonavir ensuring adequate washout before initiating bromocriptine. Use this combination with caution in patients receiving bromocriptine for other indications. Concurrent use may significantly increase bromocriptine concentrations. Bromocriptine is extensively metabolized in the liver via CYP3A4; ritonavir is a strong inhibitor of CYP3A4. [28337] [35591] [47165] Brompheniramine; Guaifenesin; Hydrocodone: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Brompheniramine; Hydrocodone; Pseudoephedrine: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Budesonide: (Major) Avoid coadministration of oral budesonide and ritonavir due to the potential for increased budesonide exposure. Use caution with inhaled forms of budesonide as systemic exposure to the corticosteroid may also increase. Budesonide is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. In the presence of another strong CYP3A4 inhibitor, the systemic exposure to oral budesonide was increased by 8-fold. [28315] [31824] [34979] [47165] (Moderate) Decreased lopinavir plasma concentrations have been observed when systemic budesonide and lopinavir are coadministered, increasing the risk for HIV treatment failure. Consider use of an alternative corticosteroid. If concurrent use is required, caution and careful monitoring of HIV treatment status is recommended. [28341] [31824] [34979] [51080] Budesonide; Formoterol: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] (Major) Avoid coadministration of oral budesonide and ritonavir due to the potential for increased budesonide exposure. Use caution with inhaled forms of budesonide as systemic exposure to the corticosteroid may also increase. Budesonide is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. In the presence of another strong CYP3A4 inhibitor, the systemic exposure to oral budesonide was increased by 8-fold. [28315] [31824] [34979] [47165] (Moderate) Decreased lopinavir plasma concentrations have been observed when systemic budesonide and lopinavir are coadministered, increasing the risk for HIV treatment failure. Consider use of an alternative corticosteroid. If concurrent use is required, caution and careful monitoring of HIV treatment status is recommended. [28341] [31824] [34979] [51080] Budesonide; Glycopyrrolate; Formoterol: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] (Major) Avoid coadministration of oral budesonide and ritonavir due to the potential for increased budesonide exposure. Use caution with inhaled forms of budesonide as systemic exposure to the corticosteroid may also increase. Budesonide is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. In the presence of another strong CYP3A4 inhibitor, the systemic exposure to oral budesonide was increased by 8-fold. [28315] [31824] [34979] [47165] (Moderate) Decreased lopinavir plasma concentrations have been observed when systemic budesonide and lopinavir are coadministered, increasing the risk for HIV treatment failure. Consider use of an alternative corticosteroid. If concurrent use is required, caution and careful monitoring of HIV treatment status is recommended. [28341] [31824] [34979] [51080] Bupivacaine Liposomal: (Minor) Bupivacaine is metabolized by cytochrome P450 (CYP) 3A4 isoenzymes. Known inhibitors of CYP 3A4, such as anti-retroviral protease inhibitors, may result in increased systemic levels of bupivacaine when given concurrently, with potential for toxicity. Although not studied, dosage adjustments of bupivacaine may be needed. [4718] Bupivacaine: (Minor) Bupivacaine is metabolized by cytochrome P450 (CYP) 3A4 isoenzymes. Known inhibitors of CYP 3A4, such as anti-retroviral protease inhibitors, may result in increased systemic levels of bupivacaine when given concurrently, with potential for toxicity. Although not studied, dosage adjustments of bupivacaine may be needed. [4718] Bupivacaine; Lidocaine: (Moderate) Anti-retroviral protease inhibitors can inhibit hepatic cytochrome P450 3A4, an isoenzyme that is partially responsible for the metabolism of lidocaine. The concurrent use of systemic lidocaine and anti-retroviral protease inhibitors should be carefully monitored due to the potential for serious toxicity. [4718] [5172] (Minor) Bupivacaine is metabolized by cytochrome P450 (CYP) 3A4 isoenzymes. Known inhibitors of CYP 3A4, such as anti-retroviral protease inhibitors, may result in increased systemic levels of bupivacaine when given concurrently, with potential for toxicity. Although not studied, dosage adjustments of bupivacaine may be needed. [4718] Buprenorphine: (Major) Avoid coadministration of lopinavir with buprenorphine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Buprenorphine has been associated with QT prolongation and has a possible risk of torsade de pointes (TdP). [28341] [41235] [41666] [60270] [65157] [65170] (Moderate) Concomitant use of buprenorphine and ritonavir can increase the plasma concentration of buprenorphine, resulting in increased or prolonged opioid effects, particularly when ritonavir is added after a stable buprenorphine dose is achieved. If concurrent use is necessary, consider dosage reduction of buprenorphine until stable drug effects are achieved. Monitor patient for respiratory depression and sedation at frequent intervals. When stopping ritonavir, the buprenorphine concentration will decrease, potentially resulting in decreased opioid efficacy or a withdrawal syndrome in patients who had developed physical dependency. If ritonavir is discontinued, consider increasing buprenorphine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal. Buprenorphine is a substrate of CYP3A4. ritonavir is a strong CYP3A4 inhibitor. [41235] [41666] [47165] Buprenorphine; Naloxone: (Major) Avoid coadministration of lopinavir with buprenorphine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Buprenorphine has been associated with QT prolongation and has a possible risk of torsade de pointes (TdP). [28341] [41235] [41666] [60270] [65157] [65170] (Moderate) Concomitant use of buprenorphine and ritonavir can increase the plasma concentration of buprenorphine, resulting in increased or prolonged opioid effects, particularly when ritonavir is added after a stable buprenorphine dose is achieved. If concurrent use is necessary, consider dosage reduction of buprenorphine until stable drug effects are achieved. Monitor patient for respiratory depression and sedation at frequent intervals. When stopping ritonavir, the buprenorphine concentration will decrease, potentially resulting in decreased opioid efficacy or a withdrawal syndrome in patients who had developed physical dependency. If ritonavir is discontinued, consider increasing buprenorphine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal. Buprenorphine is a substrate of CYP3A4. ritonavir is a strong CYP3A4 inhibitor. [41235] [41666] [47165] Bupropion: (Moderate) Concurrent administration of bupropion with ritonavir results in decreased concentrations of bupropion and its active metabolite. According to the manufacturers of bupropion, increased doses of bupropion may be necessary during concurrent therapy; however, the maximum recommended dose of bupropion should not be exceeded. Closely monitor bupropion efficacy if these drugs are given together. Ritonavir induces CYP2B6, which is responsible for bupropion's metabolism. In one study, ritonavir 100 mg twice daily reduced the AUC and Cmax of bupropion by 22% and 21%, respectively. In addition, exposure to the active metabolite of bupropion (hydroxybupropion) was decreased by 23%. When given with ritonavir 600 mg twice daily, the AUC and Cmax of bupropion decreased by 66% and 63% respectively and exposure to hydroxybupropion decreased by 78%. [28058] [28315] [34743] [34744] [34745] [34746] [44095] Bupropion; Naltrexone: (Moderate) Concurrent administration of bupropion with ritonavir results in decreased concentrations of bupropion and its active metabolite. According to the manufacturers of bupropion, increased doses of bupropion may be necessary during concurrent therapy; however, the maximum recommended dose of bupropion should not be exceeded. Closely monitor bupropion efficacy if these drugs are given together. Ritonavir induces CYP2B6, which is responsible for bupropion's metabolism. In one study, ritonavir 100 mg twice daily reduced the AUC and Cmax of bupropion by 22% and 21%, respectively. In addition, exposure to the active metabolite of bupropion (hydroxybupropion) was decreased by 23%. When given with ritonavir 600 mg twice daily, the AUC and Cmax of bupropion decreased by 66% and 63% respectively and exposure to hydroxybupropion decreased by 78%. [28058] [28315] [34743] [34744] [34745] [34746] [44095] Buspirone: (Major) When buspirone is administered with a potent inhibitor of CYP3A4 like ritonavir, a low dose of buspirone used cautiously is recommended. Some patients receiving drugs that are potent inhibitors of CYP3A4 with buspirone have reported lightheadedness, asthenia, dizziness, and drowsiness. If the two drugs are to be used in combination, a low dose of buspirone (e.g., 2.5 mg PO twice daily) is recommended. Subsequent dose adjustment of either drug should be based on clinical assessment. Several other anti-retroviral protease inhibitors also inhibit CYP3A4, and these may interact with buspirone in a similar manner. [28001] [28501] Butabarbital: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] Cabazitaxel: (Major) Avoid coadministration of cabazitaxel with ritonavir if possible due to increased cabazitaxel exposure. If concomitant use is unavoidable, consider reducing the dose of cabazitaxel by 25%. Cabazitaxel is primarily metabolized by CYP3A4 and ritonavir is a strong CYP3A4 inhibitor. In a drug interaction study, coadministration with another strong CYP3A4 inhibitor increased cabazitaxel exposure by 25%. [40981] [47165] Cabozantinib: (Major) Avoid coadministration of cabozantinib with ritonavir due to the risk of increased cabozantinib exposure. If concomitant use is unavoidable, reduce the dose of cabozantinib. For patients taking cabozantinib tablets, reduce the dose of cabozantinib by 20 mg (e.g., 60 mg/day to 40 mg/day; 40 mg/day to 20 mg/day); for patients taking cabozantinib capsules, reduce the dose of cabozantinib by 40 mg (e.g., 140 mg/day to 100 mg/day or 100 mg/day to 60 mg/day). Resume the cabozantinib dose that was used prior to initiating treatment with ritonavir 2 to 3 days after discontinuation of ritonavir. Cabozantinib is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased single-dose cabozantinib exposure by 38%. Cabozantinib is also P-glycoprotein (P-gp) inhibitor and has the potential to increase plasma concentrations of P-gp substrates such as ritonavir; however, the clinical relevance of this finding is unknown. [34557] [52506] [60738] Caffeine; Ergotamine: (Severe) Coadministration of ergot alkaloids with potent inhibitors of CYP3A4, like anti-retroviral protease inhibitors is considered contraindicated due to the risk of acute ergot toxicity (e.g., vasospasm leading to cerebral ischemia, peripheral ischemia and/or other serious effects). Several case reports have established the clinical significance of this interaction in the medical literature. In some cases, fatal interactions have occurred. [28142] [28341] [28731] [28839] [28995] [32432] [46638] [5018] [5044] [5623] [5747] [8102] Calcifediol: (Moderate) Dose adjustment of calcifediol may be necessary during coadministration with ritonavir. Additionally, serum 25-hydroxyvitamin D, intact PTH, and calcium concentrations should be closely monitored if a patient initiates or discontinues therapy with ritonavir. Ritonavir, which is a cytochrome P450 inhibitor, may inhibit enzymes involved in vitamin D metabolism (CYP24A1 and CYP27B1) and may alter serum concentrations of calcifediol. [60895] Calcium, Magnesium, Potassium, Sodium Oxybates: (Major) One case report describes a possible interaction between sodium oxybate and ritonavir and saquinavir, leading to repetitive, clonic contractions. The patient also experienced shallow respirations, a heart rate of 40 beats per min, and was responsive only to painful stimuli. The exact contribution of ritonavir and saquinavir to this reaction cannot be determined since several other compounds were detected through a urinary toxin screen. [2546] Canagliflozin: (Moderate) Monitor for decreased efficacy of canagliflozin if coadministration with ritonavir is necessary. In patients taking ritonavir who have an eGFR greater than 60 mL/min/1.73 m2, and are currently tolerating a canagliflozin dose of 100 mg once daily, increase the dose of canagliflozin to 200 mg (taken as two 100 mg tablets) once daily. In patients who are tolerating canagliflozin to 200 mg and who require additional glycemic control, the dose may be increased to 300 mg once daily. In patients taking ritonavir who have an eGFR less than 60 mL/min/1.73 m2, and are currently tolerating a canagliflozin dose of 100 mg once daily, increase the dose of canagliflozin to 200 mg (taken as two 100 mg tablets) once daily. Consider other antihyperglycemic therapy in patients who require additional glycemic control. Canagliflozin is a UGT1A9 and 2B4 substrate and ritonavir is a UGT inducer. Coadministration with a nonselective inducer of several UGT enzymes decreased canagliflozin exposure by 51%. In addition, new onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of antiretroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30575] [47165] [53972] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors, such as lopinavir. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [28341] [30575] Canagliflozin; Metformin: (Moderate) Monitor for decreased efficacy of canagliflozin if coadministration with ritonavir is necessary. In patients taking ritonavir who have an eGFR greater than 60 mL/min/1.73 m2, and are currently tolerating a canagliflozin dose of 100 mg once daily, increase the dose of canagliflozin to 200 mg (taken as two 100 mg tablets) once daily. In patients who are tolerating canagliflozin to 200 mg and who require additional glycemic control, the dose may be increased to 300 mg once daily. In patients taking ritonavir who have an eGFR less than 60 mL/min/1.73 m2, and are currently tolerating a canagliflozin dose of 100 mg once daily, increase the dose of canagliflozin to 200 mg (taken as two 100 mg tablets) once daily. Consider other antihyperglycemic therapy in patients who require additional glycemic control. Canagliflozin is a UGT1A9 and 2B4 substrate and ritonavir is a UGT inducer. Coadministration with a nonselective inducer of several UGT enzymes decreased canagliflozin exposure by 51%. In addition, new onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of antiretroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30575] [47165] [53972] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors, such as lopinavir. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [28341] [30575] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30480] [30575] Capmatinib: (Moderate) Monitor for an increase in capmatinib-related adverse reactions if coadministration with ritonavir is necessary. Capmatinib is a CYP3A substrate and ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased capmatinib exposure by 42%. [47165] [56579] [65377] Carbamazepine: (Major) Concurrent administration of lopinavir; ritonavir twice daily with carbamazepine should be done cautiously. Once daily lopinavir; ritonavir should not be administered with carbamazepine due to hepatic enzyme induction by the antiepileptic. While the use of ritonavir as a single PI has been noted to induce anticonvulsant metabolism, coadministration of lopinavir; ritonavir with carbamazepine will more likely result in decreased lopinavir plasma concentrations, leading to loss of virologic control. If lopinavir; ritonavir is used with carbamazepine, the patient's HIV status should be closely monitored. [28341] [41237] [46638] (Major) Ritonavir decreases the hepatic CYP metabolism of carbamazepine, resulting in increased carbamazepine concentrations. In addition, carbamazepine increases the metabolism of the protease inhibitors and may lead to decreased efficacy of these medications. Carbamazepine is a potent inducer and substrate of the hepatic isoenzyme CYP3A4; ritonavir is a substrate and inhibitor of this isoenzyme. In addition, carbamazepine induces P-glycoprotein (P-gp), a drug efflux transporter for which ritonavir is a substrate. Treatment failures have been reported with protease inhibitors when carbamazepine is used concomitantly. The appropriate drug-dose adjustments necessary to ensure optimum levels of both antiretroviral drugs and carbamazepine are unknown. If used concomitantly, the patient should be observed for changes in the clinical efficacy of the antiretroviral regimen or for carbamazepine toxicity. [28315] [46638] Carbetapentane; Chlorpheniramine: (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] Carbetapentane; Chlorpheniramine; Phenylephrine: (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] Carbetapentane; Diphenhydramine; Phenylephrine: (Moderate) Concurrent administration of diphenhydramine with ritonavir may result in elevated plasma concentrations of diphenhydramine. Diphenhydramine is a CYP2D6 substrate, and ritonavir is a CYP2D6 inhibitor. Caution and close monitoring are advised if these drugs are administered together. [34522] [34523] [47165] [58664] Carbinoxamine; Hydrocodone; Phenylephrine: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Carbinoxamine; Hydrocodone; Pseudoephedrine: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Cariprazine: (Major) Cariprazine and its active metabolites are extensively metabolized by CYP3A4. When a strong CYP3A4 inhibitor, such as ritonavir, is initiated in a patient who is on a stable dose of cariprazine, reduce the cariprazine dosage by half. For adult patients taking cariprazine 4.5 mg daily, the dosage should be reduced to 1.5 mg or 3 mg daily. For patients taking cariprazine 1.5 mg daily, the dosing frequency should be adjusted to every other day. When the CYP3A4 inhibitor is withdrawn, the cariprazine dosage may need to be increased. When initiating cariprazine in a patient who is stable on a strong CYP3A4 inhibitor, the patient should be administered 1.5 mg of cariprazine on Day 1 and on Day 3 with no dose administered on Day 2. From Day 4 onward, the dose should be administered at 1.5 mg daily, then increased to a maximum dose of 3 mg daily. When the CYP3A4 inhibitor is withdrawn, the cariprazine dosage may need to be increased. [28341] [60164] Carteolol: (Moderate) Cardiac and neurologic events have been reported when ritonavir was concurrently administered with beta-blockers. [5044] Carvedilol: (Moderate) Inhibitors of the hepatic CYP450 isozyme CYP2D6, such as ritonavir, may inhibit the hepatic oxidative metabolism of carvedilol. In addition, both drugs are inhibitors and subtrates for P-glycoprotein (P-gp). Close monitoring of serum drug concentrations and/or therapeutic and adverse effects is required when carvedilol is coadministered with ritonavir. [4718] [5044] [5267] Ceritinib: (Major) Avoid coadministration of ceritinib with ritonavir due to increased exposure to ceritinib; plasma concentrations of ritonavir may also increase. If concomitant use is unavoidable, decrease the dose of ceritinib by approximately one-third, rounded to the nearest multiple of 150 mg; monitor for treatment-related adverse reactions. After ritonavir is discontinued, resume the dose of ceritinib taken prior to initiating ritonavir. Both drugs are CYP3A4 substrates and strong CYP3A4 inhibitors. Coadministration with another strong CYP3A4 inhibitor increased ceritinib exposure by 2.9-fold after a single dose in healthy subjects. [47165] [57094] (Major) Avoid coadministration of lopinavir with ceritinib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Interrupt, dose reduce, or discontinue ceritinib if QT prolongation occurs. Ceritinib causes concentration-dependent QT prolongation. Lopinavir is also associated with QT prolongation. [28341] [56579] [57094] [65157] [65170] Cetirizine: (Moderate) Coadministration of cetirizine and ritonavir resulted in a 42% increase in the AUC, 53% increase in half-life, and 29% decrease in clearance of cetirizine. Cetirizine did not alter ritonavir disposition. [28874] [33350] Cetirizine; Pseudoephedrine: (Moderate) Coadministration of cetirizine and ritonavir resulted in a 42% increase in the AUC, 53% increase in half-life, and 29% decrease in clearance of cetirizine. Cetirizine did not alter ritonavir disposition. [28874] [33350] Cevimeline: (Major) Cevimeline is metabolized by CYP3A4 and CYP2D6. Anti-retroviral protease inhibitors inhibit one or both of these isoenzymes and are expected to lead to an increase in cevimeline plasma concentrations. [28001] [34711] [48617] Chloramphenicol: (Moderate) Concurrent administration of chloramphenicol with lopinavir may result in elevated lopinavir plasma concentrations, and subsequent adverse events. Chloramphenicol is an inhibitor of the hepatic isoenzyme CYP3A4; lopinavir is a substrate of this enzyme. Monitor patient for lopinavir-related adverse events. [28341] [29624] (Moderate) Concurrent administration of chloramphenicol with ritonavir may result in elevated plasma concentrations of ritonavir, and subsequent adverse events. Chloramphenicol is an inhibitor of the hepatic isoenzyme CYP3A4; ritonavir is a substrate of this enzyme. Monitor patient for ritonavir-related adverse events. [29624] [58664] Chlordiazepoxide: (Major) CYP3A4 inhibitors, such as protease inhibitors, may reduce the metabolism of chlordiazepoxide and increase the potential for benzodiazepine toxicity. A decrease in the chlordiazepoxide dose may be needed. [32432] [5286] Chlordiazepoxide; Clidinium: (Major) CYP3A4 inhibitors, such as protease inhibitors, may reduce the metabolism of chlordiazepoxide and increase the potential for benzodiazepine toxicity. A decrease in the chlordiazepoxide dose may be needed. [32432] [5286] Chloroquine: (Major) Avoid coadministration of chloroquine and lopinavir due the risk of additive QT prolongation. If use together is necessary, obtain an ECG at baseline to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Chloroquine is associated with an increased risk of QT prolongation and torsade de pointes (TdP); fatalities have been reported. The risk of QT prolongation is increased with higher chloroquine doses. Lopinavir is also associated with QT prolongation. [28229] [28230] [28231] [28341] [29758] [65157] [65170] Chlorpheniramine: (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] Chlorpheniramine; Codeine: (Moderate) Concomitant use of codeine with ritonavir may alter codeine plasma concentrations, resulting in an unpredictable effect such as reduced efficacy or symptoms of opioid withdrawal or prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage adjustment of codeine until stable drug effects are achieved. Discontinuation of ritonavir could alter codeine plasma concentrations, resulting in an unpredictable effect such as prolonged opioid adverse reactions or decreased opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If ritonavir is discontinued, monitor the patient carefully and consider adjusting the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Ritonavir is a strong inhibitor of CYP3A4 and a weak inhibitor of CYP2D6. CYP3A4 inhibitors may increase codeine-related adverse effects while CYP2D6 inhibitors may reduce efficacy. [33654] [34883] [47165] (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] Chlorpheniramine; Dextromethorphan: (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Moderate) Concomitant use of dihydrocodeine with ritonavir may increase dihydrocodeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased dihydromorphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of dihydrocodeine until stable drug effects are achieved. Discontinuation of ritonavir could decrease dihydrocodeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to dihydrocodeine. If ritonavir is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Ritonavir is a strong inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of dihydrocodeine. [30282] [47165] (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] Chlorpheniramine; Dihydrocodeine; Pseudoephedrine: (Moderate) Concomitant use of dihydrocodeine with ritonavir may increase dihydrocodeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased dihydromorphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of dihydrocodeine until stable drug effects are achieved. Discontinuation of ritonavir could decrease dihydrocodeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to dihydrocodeine. If ritonavir is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Ritonavir is a strong inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of dihydrocodeine. [30282] [47165] (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] Chlorpheniramine; Guaifenesin; Hydrocodone; Pseudoephedrine: (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Chlorpheniramine; Hydrocodone: (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Chlorpheniramine; Hydrocodone; Phenylephrine: (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Chlorpheniramine; Hydrocodone; Pseudoephedrine: (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Chlorpheniramine; Phenylephrine: (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] Chlorpheniramine; Pseudoephedrine: (Moderate) Concurrent administration of chlorpheniramine with ritonavir may result in elevated plasma concentrations of chlorpheniramine. Chlorpheniramine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Monitor for adverse effects if these drugs are administered together. [34390] [47165] [57935] [58664] Chlorpromazine: (Major) Avoid coadministration of lopinavir with chlorpromazine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). [28341] [28417] [43065] [65157] [65170] Ciclesonide: (Moderate) Coadministration of ciclesonide with ritonavir may cause elevated ciclesonide serum concentrations, potentially resulting in Cushing's syndrome and adrenal suppression. Ciclesonide is a CYP3A4 substrate; ritonavir is a strong inhibitor of CYP3A4. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use. [28341] [47165] Cidofovir: (Moderate) Additive adverse effects may be seen when cidofovir is given with other agents that cause neutropenia. Patients receiving anti-retroviral protease inhibitors in combination with cidofovir may have an increased risk of iritis or uveitis. [24859] Cilostazol: (Major) Concurrent administration of cilostazol with protease inhibitors can result in elevated cilostazol plasma concentrations; the manufacturer recommends prescribers consider up to a 50% reduction in cilostazol dosage during concurrent administration. Cilostazol is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors block this enzyme. Caution and close monitoring are advised if these drugs are administered together. [47165] [48620] Cimetidine: (Moderate) Concurrent administration of cimetidine with ritonavir may result in elevated plasma concentrations of ritonavir. Cimetidine is an inhibitor of the hepatic isoenzymes CYP3A4 and CYP2D6; ritonavir is partially metabolized by both of these enzymes. Monitor for adverse events if these drugs are administered together. [34364] [56579] [57012] [58664] Cinacalcet: (Moderate) Concurrent administration of cinacalcet with ritonavir may result in elevated plasma concentrations of cinacalcet. Cinacalcet is a substrate of CYP3A4; ritonavir is a potent inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [47165] [58664] Ciprofloxacin: (Major) Avoid coadministration of lopinavir with ciprofloxacin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Rare cases of QT prolongation and torsade de pointes (TdP) have been reported with ciprofloxacin during postmarketing surveillance. [28341] [43411] [65157] [65170] Cisapride: (Severe) Concurrent use of cisapride with anti-retroviral protease inhibitors (PI) is contraindicated due to the risk of life threatening cardiac arrhythmias such as torsade de pointes (TdP). Cisapride is metabolized by CYP3A4, and all PIs inhibit this enzyme; thus, coadministration may increases cisapride plasma concentrations and increase the risk of adverse events. Cases of QT prolongation and ventricular arrhythmias, including TdP and death, have been observed during post-marketing surveillance when cisapride is administered with potent CYP3A4 inhibitors. [28978] [28995] [46638] [47221] Citalopram: (Major) Avoid coadministration of lopinavir with citalopram due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Citalopram causes dose-dependent QT interval prolongation. [28269] [28341] [65157] [65170] (Minor) Concurrent use of ritonavir may increase citalopram exposure and treatment-related adverse effects. Ritonavir is a strong CYP3A4 inhibitor. Because CYP3A4 is one of the primary enzymes involved in the metabolism of citalopram, it is expected that strong CYP3A4 inhibitors might decrease the clearance of citalopram. However, coadministration of citalopram and another strong CYP3A4 inhibitor ketoconazole did not significantly affect the pharmacokinetics of citalopram. [28269] [47165] Clarithromycin: (Major) Avoid coadministration of lopinavir with clarithromycin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Clarithromycin is associated with an established risk for QT prolongation and torsade de pointes (TdP). [28225] [28238] [28341] [28413] [28419] [65157] [65170] (Major) Because the exposure to 14-OH clarithromycin is significantly decreased by ritonavir, consider alternative antibiotic therapy for indications other than Mycobacterium avium. Clarithromycin doses above 1000 mg should not be administered with ritonavir. If coadministration cannot be avoided, clarithromycin dosage reductions are recommended in patients with renal impairment (CrCl 30 to 60 mL/minute, decrease clarithromycin by 50%; CrCl less than 30 mL/minute, decrease clarithromycin by 75%). Concomitant administration of ritonavir and clarithromycin resulted in a 77% increase in clarithromycin exposure and a 100% decrease in 14-OH clarithromycin exposure. The microbiological activities of clarithromycin and 14-OH-clarithromycin are different for different bacteria. [28238] [46638] [47165] Clevidipine: (Moderate) Ritonavir is expected to decrease the hepatic CYP metabolism of calcium-channel blockers (mainly through CYP3A4 inhibition) resulting in increased calcium-channel blocker concentrations. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [5044] Clindamycin: (Moderate) Monitor for an increase in clindamycin-related adverse reactions with coadministration of ritonavir as concurrent use may increase clindamycin exposure. Clindamycin is a CYP3A4 substrate; ritonavir is a strong inhibitor of CYP3A4. [44982] [47165] Clobazam: (Moderate) Monitor for decreased response to lopinavir during concurrent use with clobazam. Coadministration may result in decreased lopinavir plasma concentrations. Clobazam is a weak inducer of CYP3A4. Lopinavir is a substrate of CYP3A4. [28341] [46370] [56579] (Moderate) Monitor for reduced response to ritonavir and increased adverse effects from both clobazam and ritonavir during concurrent use. Coadministration may result in elevated plasma concentrations of clobazam and altered concentrations of ritonavir. Clobazam is a substrate of CYP3A4, weak inducer of CYP3A4, and an inhibitor of CYP2D6. Ritonavir is a substrate of CYP3A4 and CYP2D6. Ritonavir is also a strong inhibitor of CYP3A4. [46370] [47165] Clofarabine: (Moderate) Concomitant use of clofarabine, a substrate of OCT1, and ritonavir, an inhibitor of OCT1, may result in increased clofarabine levels. Therefore, monitor for signs of clofarabine toxicity such as gastrointestinal toxicity (e.g., nausea, vomiting, diarrhea, mucosal inflammation), hematologic toxicity, and skin toxicity (e.g. hand and foot syndrome, rash, pruritus) in patients also receiving OCT1 inhibitors. [51834] [54578] Clofazimine: (Major) Avoid coadministration of lopinavir with clofazimine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. QT prolongation and torsade de pointes (TdP) have been reported in patients receiving clofazimine in combination with QT prolonging medications. [28341] [63936] [65157] [65170] Clomipramine: (Moderate) A dose reduction of the tricyclic antidepressant (TCA) may be necessary when coadministered with ritonavir. Concurrent use may result in elevated TCA plasma concentrations. [47165] Clonazepam: (Moderate) Use protease inhibitors cautiously and carefully monitor patients receiving concurrent clonazepam due to impaired metabolism of clonazepam leading to exaggerated concentrations and adverse effects, such as CNS and/or respiratory depression. Clonazepam is a CYP3A4 substrate. Protease inhibitors are CYP3A4 inhibitors. [28315] [28444] [32432] Clopidogrel: (Major) Avoid coadministration of clopidogrel with ritonavir due to the potential for decreased clopidogrel efficacy. Prasugrel is preferred to clopidogrel if coadministration with ritonavir is necessary. Although clopidogrel is primarily converted to its active metabolite via CYP2C19, it has been suggested that inhibition of CYP3A4 also reduces its conversion to the active metabolite, thereby reducing its antiplatelet effect. Ritonavir is a strong CYP3A4 inhibitor. [28315] [65211] [65250] Clorazepate: (Major) CYP3A4 inhibitors, such as protease inhibitors, may reduce the metabolism of N-desmethyldiazepam, the active metabolite of clorazepate, and increase the potential for benzodiazepine toxicity. Monitor patients closely who receive concurrent therapy. [46638] [4718] [5074] Clozapine: (Major) Avoid coadministration of lopinavir with clozapine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Treatment with clozapine has been associated with QT prolongation, torsade de pointes (TdP), cardiac arrest, and sudden death. [28262] [28341] [28416] [5044] [65157] [65170] (Major) Consider a clozapine dose adjustment if coadministered with ritonavir and monitor for efficacy and adverse reactions. If ritonavir is discontinued, monitor for lack of clozapine effect and adverse effects and adjust dose if necessary. A clinically relevant increase or decrease in the plasma concentration of clozapine may occur during concurrent use. Clozapine is partially metabolized by CYP3A4, CYP2D6, and CYP1A2. Ritonavir is a strong CYP3A4 and weak CYP2D6 inhibitor and a moderate inducer of CYP1A2. [28262] [47165] [56579] Cobicistat: (Severe) Use of ritonavir with cobicistat is not recommended, because of similar effects on CYP3A. Both ritonavir and cobicistat are potent inhibitors of CYP3A4. [51664] [58000] [58761] [58763] Cobimetinib: (Major) Avoid the concurrent use of cobimetinib with ritonavir due to the risk of cobimetinib toxicity. Cobimetinib is a P-glycoprotein (P-gp) substrate as well as a CYP3A substrate in vitro; ritonavir is a P-gp inhibitor as well as a strong CYP3A inhibitor. In healthy subjects (n = 15), coadministration of a single 10 mg dose of cobimetinib with itraconazole (200 mg once daily for 14 days), another strong CYP3A4 inhibitor, increased the mean cobimetinib AUC by 6.7-fold (90% CI, 5.6 to 8) and the mean Cmax by 3.2-fold (90% CI, 2.7 to 3.7). [28380] [34557] [47165] [60281] Cocaine: (Moderate) Concurrent use of cocaine with ritonavir may result in elevated plasma concentrations of cocaine and ritonavir. Cocaine is a substrate/inhibitor of CYP3A4 and an inhibitor of CYP2D6; ritonavir is a substrate/inhibitor of both these enzymes. While single uses of topical cocaine for local anethesia would not be expected to have clinically significant interactions, users of systemic cocaine could experience adverse events. [57067] [58664] Codeine: (Moderate) Concomitant use of codeine with ritonavir may alter codeine plasma concentrations, resulting in an unpredictable effect such as reduced efficacy or symptoms of opioid withdrawal or prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage adjustment of codeine until stable drug effects are achieved. Discontinuation of ritonavir could alter codeine plasma concentrations, resulting in an unpredictable effect such as prolonged opioid adverse reactions or decreased opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If ritonavir is discontinued, monitor the patient carefully and consider adjusting the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Ritonavir is a strong inhibitor of CYP3A4 and a weak inhibitor of CYP2D6. CYP3A4 inhibitors may increase codeine-related adverse effects while CYP2D6 inhibitors may reduce efficacy. [33654] [34883] [47165] Codeine; Guaifenesin: (Moderate) Concomitant use of codeine with ritonavir may alter codeine plasma concentrations, resulting in an unpredictable effect such as reduced efficacy or symptoms of opioid withdrawal or prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage adjustment of codeine until stable drug effects are achieved. Discontinuation of ritonavir could alter codeine plasma concentrations, resulting in an unpredictable effect such as prolonged opioid adverse reactions or decreased opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If ritonavir is discontinued, monitor the patient carefully and consider adjusting the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Ritonavir is a strong inhibitor of CYP3A4 and a weak inhibitor of CYP2D6. CYP3A4 inhibitors may increase codeine-related adverse effects while CYP2D6 inhibitors may reduce efficacy. [33654] [34883] [47165] Codeine; Phenylephrine; Promethazine: (Major) Avoid coadministration of lopinavir with promethazine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Promethazine, a phenothiazine, is also associated with a possible risk for QT prolongation. [28225] [28341] [55578] [65157] [65170] (Moderate) Concomitant use of codeine with ritonavir may alter codeine plasma concentrations, resulting in an unpredictable effect such as reduced efficacy or symptoms of opioid withdrawal or prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage adjustment of codeine until stable drug effects are achieved. Discontinuation of ritonavir could alter codeine plasma concentrations, resulting in an unpredictable effect such as prolonged opioid adverse reactions or decreased opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If ritonavir is discontinued, monitor the patient carefully and consider adjusting the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Ritonavir is a strong inhibitor of CYP3A4 and a weak inhibitor of CYP2D6. CYP3A4 inhibitors may increase codeine-related adverse effects while CYP2D6 inhibitors may reduce efficacy. [33654] [34883] [47165] Codeine; Promethazine: (Major) Avoid coadministration of lopinavir with promethazine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Promethazine, a phenothiazine, is also associated with a possible risk for QT prolongation. [28225] [28341] [55578] [65157] [65170] (Moderate) Concomitant use of codeine with ritonavir may alter codeine plasma concentrations, resulting in an unpredictable effect such as reduced efficacy or symptoms of opioid withdrawal or prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage adjustment of codeine until stable drug effects are achieved. Discontinuation of ritonavir could alter codeine plasma concentrations, resulting in an unpredictable effect such as prolonged opioid adverse reactions or decreased opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If ritonavir is discontinued, monitor the patient carefully and consider adjusting the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Ritonavir is a strong inhibitor of CYP3A4 and a weak inhibitor of CYP2D6. CYP3A4 inhibitors may increase codeine-related adverse effects while CYP2D6 inhibitors may reduce efficacy. [33654] [34883] [47165] Colchicine: (Major) Due to the risk for serious colchicine toxicity including multi-organ failure and death, avoid coadministration of colchicine and ritonavir in patients with normal renal and hepatic function unless the use of both agents is imperative. Coadministration is contraindicated in patients with renal or hepatic impairment because colchicine accumulation may be greater in these populations. Ritonavir can inhibit colchicine's metabolism via P-glycoprotein (P-gp) and CYP3A4, resulting in increased colchicine exposure. If coadministration in patients with normal renal and hepatic function cannot be avoided, adjust the dose of colchicine by either reducing the daily dose or the dosage frequency, and carefully monitor for colchicine toxicity. Specific dosage adjustment recommendations are available for the Colcrys product for patients who have taken ritonavir in the past 14 days or require concurrent use: for prophylaxis of gout flares, if the original dose is 0.6 mg twice daily, decrease to 0.3 mg once daily or if the original dose is 0.6 mg once daily, decrease to 0.3 mg once every other day; for treatment of gout flares, give 0.6 mg as a single dose, then 0.3 mg 1 hour later, and do not repeat for at least 3 days; for familial Mediterranean fever, do not exceed a 0.6 mg/day. [27493] [28380] [34557] [34558] [36114] [61147] Colchicine; Probenecid: (Major) Due to the risk for serious colchicine toxicity including multi-organ failure and death, avoid coadministration of colchicine and ritonavir in patients with normal renal and hepatic function unless the use of both agents is imperative. Coadministration is contraindicated in patients with renal or hepatic impairment because colchicine accumulation may be greater in these populations. Ritonavir can inhibit colchicine's metabolism via P-glycoprotein (P-gp) and CYP3A4, resulting in increased colchicine exposure. If coadministration in patients with normal renal and hepatic function cannot be avoided, adjust the dose of colchicine by either reducing the daily dose or the dosage frequency, and carefully monitor for colchicine toxicity. Specific dosage adjustment recommendations are available for the Colcrys product for patients who have taken ritonavir in the past 14 days or require concurrent use: for prophylaxis of gout flares, if the original dose is 0.6 mg twice daily, decrease to 0.3 mg once daily or if the original dose is 0.6 mg once daily, decrease to 0.3 mg once every other day; for treatment of gout flares, give 0.6 mg as a single dose, then 0.3 mg 1 hour later, and do not repeat for at least 3 days; for familial Mediterranean fever, do not exceed a 0.6 mg/day. [27493] [28380] [34557] [34558] [36114] [61147] Conivaptan: (Severe) Coadministration of conivaptan with strong CYP3A4 inhibitors like ritonavir is contraindicated. The plasma concentrations of both drugs may be elevated during concurrent use. Coadministration of conivaptan with ketoconazole, a potent CYP3A4 inhibitor, results in 4- and 11- fold increase in conivaptan Cmax and AUC, respectively; similar pharmacokinetic effects could be seen with the coadministration of conivaptan and ritonavir. In addition, conivaptan inhibits both CYP3A4 and P-glycoprotein (P-gp); ritonavir is a substrate of both CYP3A4 and P-gp. Per the manufacturer of conivaptan, concomitant use of conivaptan with CYP3A4 substrates should be avoided. Subsequent treatment with CYP3A substrates may be initiated no sooner than 1 week after completion of conivaptan therapy. [28315] [28341] [31764] [56579] (Severe) Per the manufacturer of conivaptan, concomitant use of conivaptan with CYP3A4 substrates, such as lopinavir, should be avoided. Subsequent treatment with CYP3A substrates may be initiated no sooner than 1 week after completion of conivaptan therapy. Conivaptan inhibits CYP3A4; lopinavir is a CYP3A4 substrate. [28341] [31764] Conjugated Estrogens: (Moderate) In vitro and in vivo studies have shown that estrogens are metabolized partially by CYP3A4. Inhibitors of CYP3A4, such as ritonavir, may increase the exposure of conjugated estrogens resulting in an increased risk of estrogen-related side effects or endometrial hyperplasia. Therefore, when chronically coadministering ritonavir (more than 30 days) with conjugated estrogens, adequate diagnostic measures, including directed or random endometrial sampling when indicated by signs and symptoms of endometrial hyperplasia, should be undertaken to rule out malignancy in postmenopausal women with undiagnosed persistent or recurring abnormal genital bleeding. Patients should report any breakthrough bleeding or adverse events to their prescribers. [28315] [56074] Conjugated Estrogens; Bazedoxifene: (Moderate) In vitro and in vivo studies have shown that estrogens are metabolized partially by CYP3A4. Inhibitors of CYP3A4, such as ritonavir, may increase the exposure of conjugated estrogens resulting in an increased risk of estrogen-related side effects or endometrial hyperplasia. Therefore, when chronically coadministering ritonavir (more than 30 days) with conjugated estrogens, adequate diagnostic measures, including directed or random endometrial sampling when indicated by signs and symptoms of endometrial hyperplasia, should be undertaken to rule out malignancy in postmenopausal women with undiagnosed persistent or recurring abnormal genital bleeding. Patients should report any breakthrough bleeding or adverse events to their prescribers. [28315] [56074] Conjugated Estrogens; Medroxyprogesterone: (Major) Coadministration of medroxyprogesterone, a CYP3A substrate with ritonavir, a strong CYP3A inhibitor should be avoided since it is expected to increase concentrations of medroxyprogesterone acetate. Formal drug interaction studies have not been conducted; however, medroxyprogesterone is metabolized primarily by hydroxylation via the CYP3A4 in vitro. [28380] [34557] [47165] [57648] (Moderate) In vitro and in vivo studies have shown that estrogens are metabolized partially by CYP3A4. Inhibitors of CYP3A4, such as ritonavir, may increase the exposure of conjugated estrogens resulting in an increased risk of estrogen-related side effects or endometrial hyperplasia. Therefore, when chronically coadministering ritonavir (more than 30 days) with conjugated estrogens, adequate diagnostic measures, including directed or random endometrial sampling when indicated by signs and symptoms of endometrial hyperplasia, should be undertaken to rule out malignancy in postmenopausal women with undiagnosed persistent or recurring abnormal genital bleeding. Patients should report any breakthrough bleeding or adverse events to their prescribers. [28315] [56074] Copanlisib: (Major) Avoid the concomitant use of copanlisib and ritonavir if possible; increased copanlisib exposure may occur. If coadministration cannot be avoided, reduce the copanlisib dose to 45 mg and monitor patients for copanlisib-related adverse events (e.g., hypertension, infection, and skin rash). Copanlisib is a CYP3A substrate; ritonavir is a strong CYP3A inhibitor. [47165] [62347] Crizotinib: (Major) Avoid coadministration of lopinavir with crizotinib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Interrupt, dose reduce, or discontinue crizotinib therapy if QT prolongation occurs. Crizotinib can cause concentration-dependent QT prolongation. Lopinavir is associated with QT prolongation. [28341] [45458] [65157] [65170] (Major) Avoid coadministration of ritonavir with crizotinib due to increased plasma concentrations of crizotinib. If concomitant use is unavoidable, reduce the dose of crizotinib to 250 mg by mouth once daily; resume the original crizotinib dose after discontinuation of ritonavir. Crizotinib is a CYP3A substrate. ritonavir is a strong CYP3A4 inhibitor. Coadministration with one strong CYP3A inhibitor increased the AUC and Cmax of single-dose crizotinib by 216% and 44%, respectively. Concomitant use with another strong CYP3A4 inhibitor increased the steady-state AUC and Cmax of crizotinib by 57% and 33%, respectively, compared to crizotinib alone. [45458] [47165] Cyclophosphamide: (Moderate) Monitor for an increase in cyclophosphamide-related adverse reactions if coadministration with protease inhibitors is necessary. Use of protease inhibitor-based regimens was found to be associated with a higher incidence of infections and neutropenia in patients receiving cyclophosphamide, doxorubicin, and etoposide (CDE) than the use of a Non-Nucleoside Reverse Transcriptase Inhibitor-based regimen. Concomitant use of protease inhibitors may increase the concentration of cytotoxic metabolites. [65780] [65781] [65782] Cyclosporine: (Major) An interaction is anticipated to occur with protease inhibitors and cyclosporine, as CYP3A4 is inhibited by protease inhibitors and cyclosporine is a CYP3A4 substrate. Closely monitor cyclosporine concentrations and adjust the dose of cyclosporine as appropriate if coadministration with an anti-retroviral protease inhibitor is necessary. In a study of 18 HIV-infected patients who underwent renal or hepatic transplant and received concomitant therapy with protease inhibitors and cyclosporine, there was a 3-fold increase in cyclosporine AUC resulting in an 85% reduction in cyclosporine dose over a 2-year period. In another study, HIV-infected, liver and kidney transplant patients required 4- to 5-fold reductions in cyclosporine dose and approximate 50% increases in dosing interval when cyclosporine was coadministered with protease inhibitors. Consider a reduction in cyclosporine dose to 25 mg every 1 to 2 days when coadministered with a boosted protease inhibitor. Cyclosporine toxicity, consisting of fatigue, headache, and GI distress, has been reported by a patient receiving cyclosporine and saquinavir. After receiving saquinavir for 3 days, the cyclosporine trough concentration increased from 150 to 200 mcg/mL up to 580 mcg/mL. Dosages of both agents were decreased by 50% leading to resolution of symptoms. [2357] [28142] [28341] [28839] [28995] [32432] [4718] [5936] [65478] [65479] [65481] [65482] [65483] Dabigatran: (Moderate) Increased serum concentrations of dabigatran are possible when dabigatran, a P-glycoprotein (P-gp) substrate, is coadministered with ritonavir, a P-gp inhibitor. Patients should be monitored for increased adverse effects of dabigatran. When dabigatran is administered for treatment or reduction in risk of recurrence of deep venous thrombosis (DVT) or pulmonary embolism (PE), or prophylaxis of DVT or PE following hip replacement surgery, avoid coadministration with P-gp inhibitors like ritonavir in patients with CrCl less than 50 mL/minute. When dabigatran is used in patients with non-valvular atrial fibrillation and severe renal impairment (CrCl less than 30 mL/minute), avoid coadministration with ritonavir, as serum concentrations of dabigatran are expected to be higher than when administered to patients with normal renal function. P-gp inhibition and renal impairment are the major independent factors that result in increased exposure to dabigatran. [27493] [28380] [42121] Dabrafenib: (Major) The concomitant use of dabrafenib, a CYP3A4 substrate and a moderate CYP3A4 inducer, and ritonavir, a strong CYP3A4 inhibitor and a CYP3A4 substrate and inducer, may result in altered levels of either agent; avoid concomitant use if possible. If another agent cannot be substituted and coadministration of these agents is unavoidable, monitor patients closely for dabrafenib or ritonavir adverse effects and/or reduced efficacy. [28315] [54802] (Moderate) Concomitant use of dabrafenib, a moderate CYP3A4 inducer, and lopinavir, a CYP3A4 substrate, may result in decreased lopinavir plasma concentrations. If these drugs are used together, monitor patients closely for reduced antiretroviral efficacy. [28341] [54802] Daclatasvir: (Major) The dose of daclatasvir, a CYP3A4 substrate, must be reduced to 30 mg PO once daily when administered in combination with strong CYP3A4 inhibitors, such as ritonavir. Taking these drugs together may increase daclatasvir serum concentrations, and potentially increase the risk for adverse effects. In addition, the therapeutic effects of ritonavir, a P-glycoprotein (P-gp) substrate, may be increased by daclatasvir, a P-gp inhibitor. [28380] [34557] [47165] [60001] Dapagliflozin: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [7238] [7335] Dapagliflozin; Metformin: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [7238] [7335] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30480] [30575] Dapagliflozin; Saxagliptin: (Major) The metabolism of saxagliptin is primarily mediated by CYP3A4/5. The saxagliptin dose is limited to 2.5 mg once daily when coadministered with a strong CYP3A4/5 inhibitor such as ritonavir. New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have also been reported with use of anti-retroviral protease inhibitors, such as ritonavir. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [36111] [7238] [7335] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients, including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [28341] [30575] [36111] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [7238] [7335] Dapsone: (Moderate) Concurrent administration of dapsone with ritonavir may result in elevated dapsone plasma concentrations. Dapsone is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [11191] [47165] [58664] Darifenacin: (Moderate) The daily dose of darifenacin should not exceed 7.5 mg PO when administered with ritonavir due to increased darifenacin exposure. Darifenacin is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. [30711] [47165] Darolutamide: (Moderate) Monitor patients more frequently for darolutamide-related adverse reactions if coadministration with ritonavir is necessary due to the risk of increased darolutamide exposure; decrease the dose of darolutamide for grade 3 or 4 adverse reactions or for otherwise intolerable adverse reactions. Ritonavir is a P-glycoprotein (P-gp) inhibitor and a strong CYP3A4 inhibitor; darolutamide is a CYP3A4 substrate. Concomitant use with another combined P-gp inhibitor and strong CYP3A4 inhibitor increased the mean AUC and Cmax of darolutamide by 1.7-fold and 1.4-fold, respectively. [28380] [34557] [47165] [64525] Darunavir: (Major) Coadministration of darunavir with lopinavir is not recommended. Coadministration of darunavir with lopinavir; ritonavir resulted in decreased darunavir exposure by approximately 38% to 41% depending on lopinavir; ritonavir dose. Appropriate dose adjustments for this combination have not been established. [32432] Darunavir; Cobicistat: (Severe) Use of ritonavir with cobicistat is not recommended, because of similar effects on CYP3A. Both ritonavir and cobicistat are potent inhibitors of CYP3A4. [51664] [58000] [58761] [58763] (Major) Coadministration of darunavir with lopinavir is not recommended. Coadministration of darunavir with lopinavir; ritonavir resulted in decreased darunavir exposure by approximately 38% to 41% depending on lopinavir; ritonavir dose. Appropriate dose adjustments for this combination have not been established. [32432] Darunavir; Cobicistat; Emtricitabine; Tenofovir alafenamide: (Severe) Use of ritonavir with cobicistat is not recommended, because of similar effects on CYP3A. Both ritonavir and cobicistat are potent inhibitors of CYP3A4. [51664] [58000] [58761] [58763] (Major) Coadministration of darunavir with lopinavir is not recommended. Coadministration of darunavir with lopinavir; ritonavir resulted in decreased darunavir exposure by approximately 38% to 41% depending on lopinavir; ritonavir dose. Appropriate dose adjustments for this combination have not been established. [32432] (Moderate) Concurrent use of lopinavir with tenofovir alafenamide may result in elevated tenofovir serum concentrations. Tenofovir alafenamide is a substrate for the drug transporter organic anion transporting polypeptide (OATP1B1/1B3); lopinavir is an OATP1B1 inhibitor. When 10 mg of tenofovir alafenamide was administered daily with lopinavir; ritonavir (800 mg/200 mg PO daily), the tenofovir Cmax and AUC increased by 2.19-fold and 1.47-fold, respectively. Monitor for increased toxicities if these drugs are given together. [60269] [61510] [61511] [61513] Dasabuvir; Ombitasvir; Paritaprevir; Ritonavir: (Major) Avoid coadministration of lopinavir with paritaprevir. Use of these drugs in combination has resulted in elevated paritaprevir serum concentrations. Paritaprevir is a substrate of the drugs transporter organic anion transporting polypeptide (OATP1B1); lopinavir is an OATP1B1 inhibitor. [58664] [61510] [61511] [61513] Dasatinib: (Major) Avoid coadministration of dasatinib and ritonavir due to the potential for increased dasatinib exposure and subsequent toxicity including QT prolongation and torsade de pointes (TdP). An alternative to ritonavir with no or minimal enzyme inhibition potential is recommended if possible. If coadministration cannot be avoided, consider a dasatinib dose reduction to 40 mg PO daily if original dose was 140 mg daily, 20 mg PO daily if original dose was 100 mg daily, or 20 mg PO daily if original dose was 70 mg daily. Concomitant use of ritonavir is not recommended in patients receiving dasatinib 60 mg or 40 mg daily. If dasatinib is not tolerated after dose reduction, consider alternative therapies. If ritonavir is stopped, allow a washout of approximately 1 week before increasing the dasatinib dose. Dasatinib is a CYP3A4 substrate that has the potential to prolong the QT interval; ritonavir is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased the mean Cmax and AUC of dasatinib by 4-fold and 5-fold, respectively. [47165] [60087] (Major) Avoid coadministration of lopinavir with dasatinib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. In vitro studies have shown that dasatinib has the potential to prolong the QT interval. [28341] [32387] [60087] [65157] [65170] Deferasirox: (Major) Deferasirox undergoes UGT metabolism, and ritonavir is a potent inducer of this enzyme system. The concomitant administration of deferasirox (single dose of 30 mg/kg) and the potent UGT inducer rifampin (i.e., rifampicin 600 mg/day for 9 days) resulted in a decrease in deferasirox AUC by 44%. Although specific drug interaction studies of deferasirox and ritonavir are not available, a similar interaction may occur. Avoid the concomitant use of ritonavir and deferasirox if possible. If ritonavir and deferasirox coadministration is necessary, consider increasing the initial dose of deferasirox. Monitor serum ferritin concentrations and clinical response for further modifications. [31807] Deflazacort: (Major) Decrease deflazacort dose to one third of the recommended dosage when coadministered with ritonavir. Concurrent use may significantly increase concentrations of 21-desDFZ, the active metabolite of deflazacort, resulting in an increased risk of toxicity. Deflazacort is a CYP3A4 substrate; ritonavir is a strong inhibitor of CYP3A4. Administration of deflazacort with clarithromycin, a strong CYP3A4 inhibitor, increased total exposure to 21-desDFZ by about 3-fold. [47165] [61750] Degarelix: (Major) Avoid coadministration of lopinavir with degarelix due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Androgen deprivation therapy (i.e., degarelix) may prolong the QT/QTc interval. [28341] [46869] [65157] [65170] Delavirdine: (Major) An appropriate dose combination of delavirdine and lopinavir with regards to safety and efficacy have not been established. Use of these drugs together may increase lopinavir plasma concentrations. Delavirdine is a strong CYP3A4 inhibitor; lopinavir is a CYP3A4 substrate. [28341] (Moderate) Monitor for increased toxicity of ritonavir during coadministration of delavirdine. Appropriate doses of ritonavir in combination with delavirdine with respect to safety and efficacy have not been established. The exposure to ritonavir has been increased by 70% during concurrent administration of delavirdine. [28476] [46638] [47165] Desipramine: (Moderate) A dose reduction of the tricyclic antidepressant (TCA) may be necessary when coadministered with ritonavir. Concurrent use may result in elevated TCA plasma concentrations. [47165] Deutetrabenazine: (Major) Avoid coadministration of lopinavir with deutetrabenazine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. For patients taking a deutetrabenazine dosage more than 24 mg/day, assess the QTc interval before and after increasing the deutetrabenazine dosage or other medications that prolong the QTc interval. Both drugs are associated with QT prolongation. [28341] [61845] [65157] [65170] Dexamethasone: (Moderate) Close monitoring of therapeutic and adverse effects is required when dexamethasone is coadministered with ritonavir. Ritonavir inhibits CYP3A4 and dexamethasone is a CYP3A4 substrate. [4718] [5070] [5206] (Moderate) Decreased lopinavir plasma concentrations are seen when dexamethasone and lopinavir are coadministered. Consider use of an alternative corticosteroid. If these drugs are used together, carefully monitor for decreased clinical efficacy of lopinavir. [28341] Dexlansoprazole: (Moderate) Concurrent administration of dexlansoprazole with ritonavir may result in elevated dexlansoprazole plasma concentrations. Dexlansoprazole is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and monitoring for adverse effects are advised if these drugs are administered together. [40029] [47165] [58664] Dexmedetomidine: (Moderate) Use caution if ritonavir is coadministered with dexmedetomidine due to the potential for decreased dexmedetomidine exposure which may decrease its efficacy. Limited data suggests that dexmedetomidine is metabolized by several enzymes, including CYP2C19. Ritonavir is an inducer of CYP2C19. [47165] [65210] [65222] Dextroamphetamine: (Moderate) Warn patients that the risk of amphetamine toxicity may be increased during concurrent use of ritonavir, a strong CYP2D6 inhibitor. Amphetamines are partially metabolized by CYP2D6 and have serotonergic properties; inhibition of amphetamine metabolism may increase the risk of serotonin syndrome or other toxicity. If serotonin syndrome occurs, both the amphetamine and CYP2D6 inhibitor should be discontinued and appropriate medical treatment should be implemented. [25887] [29219] [33263] [47165] [57067] Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) Concurrent administration of diphenhydramine with ritonavir may result in elevated plasma concentrations of diphenhydramine. Diphenhydramine is a CYP2D6 substrate, and ritonavir is a CYP2D6 inhibitor. Caution and close monitoring are advised if these drugs are administered together. [34522] [34523] [47165] [58664] Dextromethorphan; Promethazine: (Major) Avoid coadministration of lopinavir with promethazine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Promethazine, a phenothiazine, is also associated with a possible risk for QT prolongation. [28225] [28341] [55578] [65157] [65170] Dextromethorphan; Quinidine: (Major) Avoid coadministration of lopinavir with quinidine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Quinidine administration is associated with QT prolongation and torsade de pointes (TdP). [28341] [42280] [47357] [65157] [65170] (Major) Coadministration of HIV treatment doses of ritonavir and quinidine is contraindicated due to the potential for serious or life-threatening reactions, such as cardiac arrhythmias. Cautious consideration may be given to administering quinidine with boosting doses of ritonavir. Ritonavir is an inhibitor of CYP3A4 and increased plasma concentrations of drugs extensively metabolized by this enzyme, such as quinidine, should be expected with concurrent use. [28315] [42280] [46638] [47165] [47357] Diazepam: (Major) CYP3A4 inhibitors, such as protease inhibitors, may reduce the metabolism of diazepam and increase the potential for benzodiazepine toxicity. Prolonged sedation and respiratory depression can occur. A decrease in the diazepam dose may be needed [28001] [28345] [28556] [47165] [55901] Diclofenac: (Moderate) Concurrent administration of diclofenac with ritonavir may result in elevated diclofenac plasma concentrations. Diclofenac is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring for adverse effects are advised if these drugs are administered together. [11181] [47165] [58664] Diclofenac; Misoprostol: (Moderate) Concurrent administration of diclofenac with ritonavir may result in elevated diclofenac plasma concentrations. Diclofenac is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring for adverse effects are advised if these drugs are administered together. [11181] [47165] [58664] Dienogest; Estradiol valerate: (Moderate) Ritonavir has been shown to increase the metabolism of ethinyl estradiol. Ritonavir is a substrate and inhibitor of CYP3A4. It is not known if the effects of protease inhibitors are similar on estradiol; however, estradiol is metabolized by CYP3A4, similar to ethinyl estradiol. [28315] Digoxin: (Major) In a pharmacokinetic study of 11 healthy men, increases in digoxin AUC (86%), volume of distribution, and half-life were seen, while renal and non-renal clearance decreased, when coadministered with ritonavir. It appears that this interaction is mediated by ritonavir's inhibition or P-glycoprotein-mediated renal tubular secretion of digoxin. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including digoxin) has not been evaluated. Measure serum digoxin concentrations before initiating ritonavir or lopinavir; ritonavir. Reduce digoxin concentrations by decreasing the digoxin dose by approximately 30 to 50% or by modifying the dosing frequency and continue monitoring. [28272] [28380] [30195] Dihydrocodeine; Guaifenesin; Pseudoephedrine: (Moderate) Concomitant use of dihydrocodeine with ritonavir may increase dihydrocodeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased dihydromorphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of dihydrocodeine until stable drug effects are achieved. Discontinuation of ritonavir could decrease dihydrocodeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to dihydrocodeine. If ritonavir is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Ritonavir is a strong inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of dihydrocodeine. [30282] [47165] Dihydroergotamine: (Severe) Coadministration of ergot alkaloids with potent inhibitors of CYP3A4, like anti-retroviral protease inhibitors is considered contraindicated due to the risk of acute ergot toxicity (e.g., vasospasm leading to cerebral ischemia, peripheral ischemia and/or other serious effects). Several case reports have established the clinical significance of this interaction in the medical literature. In some cases, fatal interactions have occurred. [28142] [28341] [28731] [28839] [28995] [32432] [46638] [5018] [5044] [5623] [5747] [8102] Diltiazem: (Major) Ritonavir is expected to decreases the hepatic CYP metabolism of diltiazem, resulting in increased diltiazem concentrations. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased diltiazem may be warranted. In addition, ritonavir and diltiazem both prolong the PR interval and caution for increased risk is recommended with coadministration. [4718] [5044] Diphenhydramine: (Moderate) Concurrent administration of diphenhydramine with ritonavir may result in elevated plasma concentrations of diphenhydramine. Diphenhydramine is a CYP2D6 substrate, and ritonavir is a CYP2D6 inhibitor. Caution and close monitoring are advised if these drugs are administered together. [34522] [34523] [47165] [58664] Diphenhydramine; Hydrocodone; Phenylephrine: (Moderate) Concurrent administration of diphenhydramine with ritonavir may result in elevated plasma concentrations of diphenhydramine. Diphenhydramine is a CYP2D6 substrate, and ritonavir is a CYP2D6 inhibitor. Caution and close monitoring are advised if these drugs are administered together. [34522] [34523] [47165] [58664] (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Diphenhydramine; Ibuprofen: (Moderate) Concurrent administration of diphenhydramine with ritonavir may result in elevated plasma concentrations of diphenhydramine. Diphenhydramine is a CYP2D6 substrate, and ritonavir is a CYP2D6 inhibitor. Caution and close monitoring are advised if these drugs are administered together. [34522] [34523] [47165] [58664] Diphenhydramine; Naproxen: (Moderate) Concurrent administration of diphenhydramine with ritonavir may result in elevated plasma concentrations of diphenhydramine. Diphenhydramine is a CYP2D6 substrate, and ritonavir is a CYP2D6 inhibitor. Caution and close monitoring are advised if these drugs are administered together. [34522] [34523] [47165] [58664] Diphenhydramine; Phenylephrine: (Moderate) Concurrent administration of diphenhydramine with ritonavir may result in elevated plasma concentrations of diphenhydramine. Diphenhydramine is a CYP2D6 substrate, and ritonavir is a CYP2D6 inhibitor. Caution and close monitoring are advised if these drugs are administered together. [34522] [34523] [47165] [58664] Disopyramide: (Major) Avoid coadministration of lopinavir with disopyramide due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Disopyramide is associated with QT prolongation and torsade de pointes (TdP). [28228] [28341] [65157] [65170] (Major) Caution is warranted when ritonavir is coadministered with antiarrhythmics, including disopyramide. Ritonavir is an inhibitor of CYP3A4, and increased concentrations of disopyramide may be expected during coadministration. Therapeutic antiarrhythmic concentration monitoring is suggested when available. Monitor therapeutic response closely; dosage reduction may be needed. In some cases, the drug interaction may require more than 50% dosage reduction due to potent inhibitory effects and drug accumulation. Cardiac and neurologic events have been reported when ritonavir was concurrently administered with disopyramide. [28001] [28228] [28315] Disulfiram: (Major) Oral solutions of ritonavir contain ethanol. Administration of ritonavir oral solution to patients receiving or who have recently received disulfiram may result in disulfiram-like reactions. A disulfiram reaction would not be expected to occur with non-ethanol containing formulations. [28315] [48545] (Major) The ingestion of ethanol by patients receiving disulfiram causes an extremely unpleasant reaction ('Antabuse Reaction') that can last from 30 minutes to several hours; however, the intensity and duration are dependent upon the disulfiram dosage. Oral solutions of lopinavir; ritonavir contain ethanol. Administration of lopinavir; ritonavir oral solution to patients receiving or who have recently received disulfiram may result in antabuse reactions. A disulfiram reaction would not be expected to occur with non-ethanol containing formulations. [28341] [48545] Docetaxel: (Major) Avoid coadministration of docetaxel with ritonavir if possible due to increased plasma concentrations of docetaxel. If concomitant use is unavoidable, closely monitor for docetaxel-related adverse reactions and consider a 50% dose reduction of docetaxel. Docetaxel is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Concomitant use with another strong CYP3A4 inhibitor increased docetaxel exposure by 2.2-fold. [47165] [60484] (Moderate) Monitor for docetaxel-related adverse reactions during coadministration with lopinavir as concurrent use may increase exposure of docetaxel. Docetaxel is a substrate of the drug transporter organic anion transporting polypeptide (OATP1B1); lopinavir is an OATP1B1 inhibitor. [28341] [56579] [60484] [63168] Dofetilide: (Major) Avoid coadministration of lopinavir with dofetilide due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Dofetilide, a Class III antiarrhythmic agent, is associated with a well-established risk of QT prolongation and torsade de pointes (TdP). [28221] [28341] [28432] [28457] [65157] [65170] (Moderate) Concomitant use of dofetilide and ritonavir may increase the risk of QT prolongation and torsade de pointes (TdP) due to increased dofetilide exposure. Dofetilide is metabolized to a small degree by CYP3A4; ritonavir is a potent inhibitor of CYP3A4. [28221] [47165] Dolasetron: (Major) Avoid coadministration of lopinavir with dolasetron due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Dolasetron has been associated with a dose-dependent prolongation in the QT, PR, and QRS intervals on an electrocardiogram. [28341] [42844] [65157] [65170] Dolutegravir; Rilpivirine: (Major) Avoid coadministration of lopinavir with rilpivirine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Supratherapeutic doses of rilpivirine (75 to 300 mg/day) have caused QT prolongation. [28341] [44376] [65157] [65170] Donepezil: (Major) Avoid coadministration of lopinavir with donepezil due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Case reports indicate that QT prolongation and torsade de pointes (TdP) can occur during donepezil therapy. [28341] [59321] [59322] [65157] [65170] (Moderate) The plasma concentrations of donepezil may be elevated when administered concurrently with ritonavir. Clinical monitoring for adverse effects, such as GI or cholinergic effects, is recommended during coadministration. Ritonavir is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor, while donepezil is a CYP3A4 and CYP2D6 substrate. [29640] [47165] Donepezil; Memantine: (Major) Avoid coadministration of lopinavir with donepezil due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Case reports indicate that QT prolongation and torsade de pointes (TdP) can occur during donepezil therapy. [28341] [59321] [59322] [65157] [65170] (Moderate) The plasma concentrations of donepezil may be elevated when administered concurrently with ritonavir. Clinical monitoring for adverse effects, such as GI or cholinergic effects, is recommended during coadministration. Ritonavir is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor, while donepezil is a CYP3A4 and CYP2D6 substrate. [29640] [47165] Doravirine: (Minor) Coadministration of doravirine and ritonavir may result in increased doravirine plasma concentrations. Doravirine is a CYP3A4 substrate; ritonavir is a strong inhibitor. In a drug interaction study, concurrent use of ritonavir increased doravirine exposure by more than 3-fold; however, this increase was not considered clinically significant. [63484] Doravirine; Lamivudine; Tenofovir disoproxil fumarate: (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrate, concurrently with inhibitors of P-gp and BCRP, such as ritonavir. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. [28193] [58664] (Minor) Coadministration of doravirine and ritonavir may result in increased doravirine plasma concentrations. Doravirine is a CYP3A4 substrate; ritonavir is a strong inhibitor. In a drug interaction study, concurrent use of ritonavir increased doravirine exposure by more than 3-fold; however, this increase was not considered clinically significant. [63484] (Minor) There are varying results in reports of an interaction between tenofovir and lopinavir; ritonavir. In one report, the concurrent administration of tenofovir with lopinavir; ritonavir increased tenofovir Cmax 31%, AUC 34%, and Cmin 29%, with slight (15%) decreases in lopinavir Cmax and AUC; the alterations may be a food effect rather than a drug-drug interaction. In another report, lopinavir; ritonavir (400 mg; 100 mg PO twice daily for 14 days) increased the tenofovir (300 mg/day PO) Cmin 51% and AUC 32%, with no effect seen on lopinavir; ritonavir pharmacokinetics. While the clinical significance of this interaction is unknown, and is suspected to be insignificant, patients receiving lopinavir; ritonavir with tenofovir should be monitored for tenofovir-associated adverse events. [46638] Dorzolamide; Timolol: (Moderate) Timolol is significantly metabolized by CYP2D6 isoenzymes. CYP2D6 inhibitors, such as ritonavir, may impair timolol metabolism; the clinical significance of such interactions is unknown. [5044] [5270] Doxazosin: (Moderate) Monitor blood pressure and for signs of hypotension during coadministration. The plasma concentrations of doxazosin may be elevated when administered concurrently with ritonavir. Ritonavir is a strong CYP3A4 inhibitor; doxazosin is a CYP3A4 substrate. Coadministration of doxazosin with a moderate CYP3A4 inhibitor resulted in a 10% increase in mean AUC and an insignificant increase in mean Cmax and mean half-life of doxazosin. Although not studied in combination with doxazosin, strong CYP3A4 inhibitors may have a larger impact on doxazosin concentrations and therefore should be used with caution. [29824] [47165] [56579] Doxepin: (Moderate) A dose reduction of the tricyclic antidepressant (TCA) may be necessary when coadministered with ritonavir. Concurrent use may result in elevated TCA plasma concentrations. [47165] Doxercalciferol: (Moderate) Protease inhibitors may decrease efficacy of doxercalciferol. Doxercalciferol is converted in the liver to 1,25-dihydroxyergocalciferol, the major active metabolite, and 1-alpha, 24-dihydroxyvitamin D2, a minor metabolite. Although not specifically studied, cytochrome P450 enzyme inhibitors, including protease inhibitors, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if these drugs are administered together. [30802] [49493] Doxorubicin Liposomal: (Major) Avoid coadministration of ritonavir with doxorubicin due to increased systemic exposure of doxorubicin resulting in increased treatment-related adverse reactions. Ritonavir is a strong CYP3A4 inhibitor and a P-gp inhibitor; doxorubicin is a CYP3A4 and P-gp substrate. Concurrent use of CYP3A4 and/or P-gp inhibitors with doxorubicin has resulted in clinically significant interactions. [47165] [56361] Doxorubicin: (Major) Avoid coadministration of ritonavir with doxorubicin due to increased systemic exposure of doxorubicin resulting in increased treatment-related adverse reactions. Ritonavir is a strong CYP3A4 inhibitor and a P-gp inhibitor; doxorubicin is a CYP3A4 and P-gp substrate. Concurrent use of CYP3A4 and/or P-gp inhibitors with doxorubicin has resulted in clinically significant interactions. [47165] [56361] Dronabinol: (Major) Use caution if coadministration of dronabinol with ritonavir is necessary, and closely monitor for an increase in dronabinol-related adverse reactions (e.g., cognitive impairment, psychosis, seizures, and hemodynamic instability, as well as feeling high, dizziness, confusion, somnolence). Ritonavir is a strong inhibitor of CYP3A4 and a moderate CYP2C9 inducer; it is contraindicated with sensitive drugs that are highly dependent on CYP3A4/5 for clearance. Dronabinol is a CYP2C9 and 3A4 substrate; concomitant use may result in elevated plasma concentrations of dronabinol. [30431] [47165] [60951] Dronedarone: (Severe) Coadministration of lopinavir; ritonavir with dronedarone is contraindicated due to the potential for additive QT prolongation. Dronedarone is highly dependent on CYP3A for clearance. Dronedarone administration is associated with a dose-related increase in the QTc interval. The increase in QTc is approximately 10 milliseconds at doses of 400 mg twice daily (the FDA-approved dose) and up to 25 milliseconds at doses of 1,600 mg twice daily. Lopinavir; ritonavir is a potent CYP3A inhibitor and is also associated with QT prolongation. [28341] [36101] (Severe) The concomitant use of dronedarone and ritonavir is contraindicated. Dronedarone is metabolized by CYP3A, is a moderate inhibitor of CYP3A, and is an inhibitor of P-gp. Ritonavir is a strong inhibitor of CYP3A4, is an inducer of CYP3A, and is a substrate of CYP3A and P-gp. Repeated doses of ketoconazole, also a strong CYP3A4 inhibitor, increased dronedarone exposure 17-fold and increased dronedarone Cmax 9-fold. Furthermore, coadministration of dronedarone and ritonavir may, theoretically, result in decreased concentrations of dronedarone due to CYP3A induction by ritonavir; the net effect on dronedarone plasma concentrations is not known. However, no data exist regarding the safe administration of dronedarone with strong CYP3A4 inhibitors; therefore, concomitant use is contraindicated. Also, the effects of dronedarone on the pharmacokinetics of ritonavir have not been described, although an increase in ritonavir serum concentrations is possible. [36101] Droperidol: (Major) Avoid coadministration of lopinavir with droperidol due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Initiate droperidol at a low dose and titrate as needed to achieve the desired effect. Lopinavir is associated with QT prolongation. Droperidol is associated with an established risk for QT prolongation and torsade de pointes (TdP). [28235] [28236] [28237] [28341] [28737] [51289] [65157] [65170] Drospirenone; Estradiol: (Moderate) Ritonavir has been shown to increase the metabolism of ethinyl estradiol. Ritonavir is a substrate and inhibitor of CYP3A4. It is not known if the effects of protease inhibitors are similar on estradiol; however, estradiol is metabolized by CYP3A4, similar to ethinyl estradiol. [28315] Drospirenone; Ethinyl Estradiol: (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] Drospirenone; Ethinyl Estradiol; Levomefolate: (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] Dutasteride: (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [28001] [28875] Dutasteride; Tamsulosin: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. [29677] [4194] [8102] (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [28001] [28875] Duvelisib: (Major) Reduce duvelisib dose to 15 mg PO twice daily and monitor for increased toxicity when coadministered with ritonavir. Coadministration may increase the exposure of duvelisib. Duvelisib is a CYP3A substrate; ritonavir is a strong CYP3A inhibitor. The increase in exposure to duvelisib is estimated to be approximately 2-fold when used concomitantly with strong CYP3A inhibitors such as ritonavir. [47165] [63571] Echinacea: (Moderate) Use Echinacea sp. with caution in patients taking medications for human immunodeficiency virus (HIV) infection. Some experts have suggested that Echinacea's effects on the immune system might cause problems for patients with HIV infection, particularly with long-term use. There may be less risk with short-term use (less than 2 weeks). A few pharmacokinetic studies have shown reductions in blood levels of some antiretroviral medications when Echinacea was given, presumably due to CYP induction. However, more study is needed for various HIV treatment regimens. Of the agents studied, the interactions do not appear to be significant or to require dose adjustments at the time of use. Although no dose adjustments are required, monitoring drug concentrations may give reassurance during co-administration. Monitor viral load and other parameters carefully during therapy. [25398] [30456] [61924] [61926] [61927] Edoxaban: (Moderate) Coadministration of edoxaban and ritonavir may result in increased concentrations of edoxaban. Edoxaban is a P-glycoprotein (P-gp) substrate and ritonavir is a P-gp inhibitor. Increased concentrations of edoxaban may occur during concomitant use of ritonavir; monitor for increased adverse effects of edoxaban. Dosage reduction may be considered for patients being treated for deep venous thrombosis (DVT) or pulmonary embolism. [28315] [58685] Efavirenz: (Major) Avoid coadministration of lopinavir; ritonavir with efavirenz due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Additionally, increase the dose of lopinavir; ritonavir to 500/125 mg and administer twice daily in adults; do not use once daily administration. Induction of CYP3A4 by efavirenz may decrease lopinavir concentrations. Both drugs have been associated with QT prolongation. [28341] [28442] [32514] [42452] [46638] [51080] (Moderate) Monitor for elevation of liver enzymes and for adverse clinical experiences (e.g., dizziness, nausea, paresthesia) when efavirenz is coadministered with ritonavir. Concurrent use is is expected to result in increased concentrations of both drugs. [28442] [47165] Efavirenz; Emtricitabine; Tenofovir: (Major) Avoid coadministration of lopinavir; ritonavir with efavirenz due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Additionally, increase the dose of lopinavir; ritonavir to 500/125 mg and administer twice daily in adults; do not use once daily administration. Induction of CYP3A4 by efavirenz may decrease lopinavir concentrations. Both drugs have been associated with QT prolongation. [28341] [28442] [32514] [42452] [46638] [51080] (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrate, concurrently with inhibitors of P-gp and BCRP, such as ritonavir. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. [28193] [58664] (Moderate) Monitor for elevation of liver enzymes and for adverse clinical experiences (e.g., dizziness, nausea, paresthesia) when efavirenz is coadministered with ritonavir. Concurrent use is is expected to result in increased concentrations of both drugs. [28442] [47165] (Minor) There are varying results in reports of an interaction between tenofovir and lopinavir; ritonavir. In one report, the concurrent administration of tenofovir with lopinavir; ritonavir increased tenofovir Cmax 31%, AUC 34%, and Cmin 29%, with slight (15%) decreases in lopinavir Cmax and AUC; the alterations may be a food effect rather than a drug-drug interaction. In another report, lopinavir; ritonavir (400 mg; 100 mg PO twice daily for 14 days) increased the tenofovir (300 mg/day PO) Cmin 51% and AUC 32%, with no effect seen on lopinavir; ritonavir pharmacokinetics. While the clinical significance of this interaction is unknown, and is suspected to be insignificant, patients receiving lopinavir; ritonavir with tenofovir should be monitored for tenofovir-associated adverse events. [46638] Efavirenz; Lamivudine; Tenofovir Disoproxil Fumarate: (Major) Avoid coadministration of lopinavir; ritonavir with efavirenz due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Additionally, increase the dose of lopinavir; ritonavir to 500/125 mg and administer twice daily in adults; do not use once daily administration. Induction of CYP3A4 by efavirenz may decrease lopinavir concentrations. Both drugs have been associated with QT prolongation. [28341] [28442] [32514] [42452] [46638] [51080] (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrate, concurrently with inhibitors of P-gp and BCRP, such as ritonavir. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. [28193] [58664] (Moderate) Monitor for elevation of liver enzymes and for adverse clinical experiences (e.g., dizziness, nausea, paresthesia) when efavirenz is coadministered with ritonavir. Concurrent use is is expected to result in increased concentrations of both drugs. [28442] [47165] (Minor) There are varying results in reports of an interaction between tenofovir and lopinavir; ritonavir. In one report, the concurrent administration of tenofovir with lopinavir; ritonavir increased tenofovir Cmax 31%, AUC 34%, and Cmin 29%, with slight (15%) decreases in lopinavir Cmax and AUC; the alterations may be a food effect rather than a drug-drug interaction. In another report, lopinavir; ritonavir (400 mg; 100 mg PO twice daily for 14 days) increased the tenofovir (300 mg/day PO) Cmin 51% and AUC 32%, with no effect seen on lopinavir; ritonavir pharmacokinetics. While the clinical significance of this interaction is unknown, and is suspected to be insignificant, patients receiving lopinavir; ritonavir with tenofovir should be monitored for tenofovir-associated adverse events. [46638] Elagolix: (Severe) Concomitant use of elagolix and organic anion transporting polypeptide (OATP) 1B1 inhibitors such as lopinavir is contraindicated. Use of elagolix with drugs that inhibit OATP1B1 may increase elagolix plasma concentrations. Elagolix is a substrate of OATP1B1. Lopinavir inhibits OATP1B1. Increased elagolix concentrations increase the risk for dose-related side effects, including loss of bone mineral density. [28341] [63387] (Major) Concomitant use of elagolix 200 mg twice daily and ritonavir for more than 1 month is not recommended. Limit concomitant use of elagolix 150 mg once daily and ritonavir to 6 months. Monitor for elagolix-related side effects and reduced response to ritonavir. Elagolix is a CYP3A substrate and a weak to moderate CYP3A4 inducer; ritonavir is a strong inhibitor of CYP3A and a CYP3A4 substrate. Coadministration may increase elagolix plasma concentrations and decrease ritonavir concentrations. In drug interaction studies, coadministration of elagolix with another strong CYP3A inhibitor increased the Cmax and AUC of elagolix by 77% and 120%, respectively. [28341] [63387] Elagolix; Estradiol; Norethindrone acetate: (Severe) Concomitant use of elagolix and organic anion transporting polypeptide (OATP) 1B1 inhibitors such as lopinavir is contraindicated. Use of elagolix with drugs that inhibit OATP1B1 may increase elagolix plasma concentrations. Elagolix is a substrate of OATP1B1. Lopinavir inhibits OATP1B1. Increased elagolix concentrations increase the risk for dose-related side effects, including loss of bone mineral density. [28341] [63387] (Major) Concomitant use of elagolix 200 mg twice daily and ritonavir for more than 1 month is not recommended. Limit concomitant use of elagolix 150 mg once daily and ritonavir to 6 months. Monitor for elagolix-related side effects and reduced response to ritonavir. Elagolix is a CYP3A substrate and a weak to moderate CYP3A4 inducer; ritonavir is a strong inhibitor of CYP3A and a CYP3A4 substrate. Coadministration may increase elagolix plasma concentrations and decrease ritonavir concentrations. In drug interaction studies, coadministration of elagolix with another strong CYP3A inhibitor increased the Cmax and AUC of elagolix by 77% and 120%, respectively. [28341] [63387] (Moderate) Many anti-retroviral protease inhibitors may interact with hormonal agents like norethindrone, due to their actions on CYP metabolism, particularly CYP3A4. Data on the effects that protease inhibitors have on the serum concentrations of norethindrone are complex and are based mostly off of data with norethindrone-containing contraceptives. For example, ritonavir (also found in combinations like lopinavir; ritonavir, and used as a booster in many HIV treatment regimens) may decrease the metabolism of norethindrone, raising norethindrone concentrations. Women receiving norethindrone for hormone replacement or contraception should report potential hormonal adverse effects (e.g., bleeding pattern changes, acne, emotional lability) or any changes in efficacy (e.g., noted changes in bleeding patterns) to their prescribers. Because norethindrone-containing contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive norethindrone contraception concurrently with ritonavir should use an additional barrier method of contraception such as condoms. [58679] [7731] (Moderate) Ritonavir has been shown to increase the metabolism of ethinyl estradiol. Ritonavir is a substrate and inhibitor of CYP3A4. It is not known if the effects of protease inhibitors are similar on estradiol; however, estradiol is metabolized by CYP3A4, similar to ethinyl estradiol. [28315] Elbasvir; Grazoprevir: (Severe) Concurrent administration of grazoprevir with lopinavir is contraindicated. Use of these drugs together is expected to significantly increase the plasma concentrations of grazoprevir, and may result in adverse effects (i.e., elevated ALT concentrations). Lopinavir is an inhibitor of the organic anion transporting protein (OATP1B1). Grazoprevir is also a substrate of OATP1B1/3. [28341] [60523] [61510] [61511] [61513] (Major) Concurrent administration of elbasvir with ritonavir should be avoided if possible. Use of these drugs together is expected to significantly increase the plasma concentrations of elbasvir, and may result in adverse effects (i.e., elevated ALT concentrations and hepatotoxicity). Ritonavir is a strong inhibitor of the hepatic enzyme CYP3A, while elbasvir is metabolized by CYP3A. [47165] [60523] (Major) Concurrent administration of grazoprevir with ritonavir should be avoided if possible. Use of these drugs together is expected to significantly increase the plasma concentrations of grazoprevir, and may result in adverse effects (i.e., elevated ALT concentrations and hepatotoxicity). Ritonavir is a strong inhibitor of the hepatic enzyme CYP3A, while grazoprevir is metabolized by CYP3A. In addition, concentrations of ritonavir (also a CYP3A substrate) may be increased when given with grazoprevir (a weak CYP3A inhibitor). [47165] [60523] Eletriptan: (Severe) Eletriptan is contraindicated for use within 72 hours of using any drug that is a potent CYP3A4 inhibitor as described in the prescribing information of the interacting drug including protease inhibitors. Eletriptan is metabolized via CYP3A4, and coadministration with protease inhibitors may cause increased eletriptan concentrations and thus toxicity. [28341] [47165] Elexacaftor; tezacaftor; ivacaftor: (Major) If ritonavir and ivacaftor are taken together, administer ivacaftor at the usual recommended dose but reduce the frequency to twice weekly. Ivacaftor is a CYP3A substrate and ritonavir is a CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased ivacaftor exposure by 8.5-fold. [48524] (Major) Reduce the dosing frequency of elexacaftor; tezacaftor; ivacaftor when coadministered with ritonavir; coadministration may increase elexacaftor; tezacaftor; ivacaftor exposure and adverse reactions. When combined, dose 2 elexacaftor/tezacaftor/ivacaftor combination tablets twice a week, approximately 3 to 4 days apart (i.e., Day 1 and Day 4). The evening dose of ivacaftor should not be taken. Elexacaftor, tezacaftor, and ivacaftor are CYP3A4 substrates (ivacaftor is a sensitive substrate); ritonavir is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor increased elexacaftor exposure by 2.8- fold, tezacaftor exposure by 4.5-fold, and ivacaftor exposure by 15.6-fold. [47165] [64697] (Major) Reduce the dosing frequency of tezacaftor; ivacaftor when coadministered with ritonavir; coadministration may increase tezacaftor; ivacaftor exposure and adverse reactions. When combined, dose 1 tezacaftor; ivacaftor combination tablet twice a week, approximately 3 to 4 days apart (i.e., Day 1 and Day 4). The evening dose of ivacaftor should not be taken. Both tezacaftor and ivacaftor are CYP3A substrates (ivacaftor is a sensitive substrate); ritonavir is a strong CYP3A inhibitor. Coadministration of a strong CYP3A inhibitor increased tezacaftor and ivacaftor exposure 4- and 15.6-fold, respectively. [47165] [62870] Eliglustat: (Major) Avoid coadministration of lopinavir with eliglustat due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Eliglustat is predicted to cause PR, QRS, and/or QT prolongation at significantly elevated plasma concentrations. [28341] [57803] [65157] [65170] (Major) Coadministration of eliglustat and ritonavir is contraindicated in intermediate or poor CYP2D6 metabolizers (IMs or PMs). In extensive CYP2D6 metabolizers (EMs), coadministration of these agents requires dosage reduction of eliglustat to 84 mg PO once daily. The coadministration of eliglustat with ritonavir and a moderate or strong CYP2D6 inhibitor is contraindicated in all patients. Eliglustat is a CYP3A and CYP2D6 substrate. Coadministration of eliglustat with CYP3A inhibitors, such as ritonavir, increases eliglustat exposure and the risk of serious adverse events (e.g., QT prolongation and cardiac arrhythmias); this risk is the highest in CYP2D6 IMs and PMs because a larger portion of the eliglustat dose is metabolized via CYP3A. [28341] [47165] [57803] Eltrombopag: (Moderate) Eltrombopag is metabolized by CYP1A2. The significance of administering inducers of CYP1A2, such as ritonavir, on the systemic exposure of eltrombopag has not been established. Monitor patients for a decrease in the efficacy of eltrombopag if these drugs are coadministered. [27493] [28315] [40392] Eluxadoline: (Major) When administered concurrently with lopinavir, the dose of eluxadoline must be reduced to 75 mg PO twice daily, and the patient should be closely monitored for eluxadoline-related adverse effects (i.e., decreased mental and physical acuity). Eluxadoline is a substrate of the organic anion-transporting peptide (OATP1B1); lopinavir is an OATP1B1 inhibitor. Advise patients against driving or operating machinery until the combine effects of these drugs on the individual patient is known. [59741] [61510] [61511] [61513] (Major) When administered concurrently with ritonavir, the dose of eluxadoline must be reduced to 75 mg PO twice daily, and the patient should be closely monitored for eluxadoline-related adverse effects (i.e., decreased mental and physical acuity). Advise patients against driving or operating machinery until the combine effects of these drugs on the individual patient is known. Eluxadoline is a substrate of the organic anion-transporting peptide (OATP1B1); ritonavir is an OATP1B1 inhibitor. [59741] Elvitegravir: (Moderate) Concurrent administration of elvitegravir with ritonavir may result in elevated elvitegravir plasma concentrations. Elvitegravir is a substrate of the hepatic isoenzyme CYP3A4. Ritonavir inhibits the CYP3A4 enzyme. Caution and close monitoring are advised if these drugs are administered together. [51664] [58001] [58664] Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Alafenamide: (Severe) Use of ritonavir with cobicistat is not recommended, because of similar effects on CYP3A. Both ritonavir and cobicistat are potent inhibitors of CYP3A4. [51664] [58000] [58761] [58763] (Moderate) Concurrent administration of elvitegravir with ritonavir may result in elevated elvitegravir plasma concentrations. Elvitegravir is a substrate of the hepatic isoenzyme CYP3A4. Ritonavir inhibits the CYP3A4 enzyme. Caution and close monitoring are advised if these drugs are administered together. [51664] [58001] [58664] (Moderate) Concurrent use of lopinavir with tenofovir alafenamide may result in elevated tenofovir serum concentrations. Tenofovir alafenamide is a substrate for the drug transporter organic anion transporting polypeptide (OATP1B1/1B3); lopinavir is an OATP1B1 inhibitor. When 10 mg of tenofovir alafenamide was administered daily with lopinavir; ritonavir (800 mg/200 mg PO daily), the tenofovir Cmax and AUC increased by 2.19-fold and 1.47-fold, respectively. Monitor for increased toxicities if these drugs are given together. [60269] [61510] [61511] [61513] Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Disoproxil Fumarate: (Severe) Use of ritonavir with cobicistat is not recommended, because of similar effects on CYP3A. Both ritonavir and cobicistat are potent inhibitors of CYP3A4. [51664] [58000] [58761] [58763] (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrate, concurrently with inhibitors of P-gp and BCRP, such as ritonavir. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. [28193] [58664] (Moderate) Concurrent administration of elvitegravir with ritonavir may result in elevated elvitegravir plasma concentrations. Elvitegravir is a substrate of the hepatic isoenzyme CYP3A4. Ritonavir inhibits the CYP3A4 enzyme. Caution and close monitoring are advised if these drugs are administered together. [51664] [58001] [58664] (Minor) There are varying results in reports of an interaction between tenofovir and lopinavir; ritonavir. In one report, the concurrent administration of tenofovir with lopinavir; ritonavir increased tenofovir Cmax 31%, AUC 34%, and Cmin 29%, with slight (15%) decreases in lopinavir Cmax and AUC; the alterations may be a food effect rather than a drug-drug interaction. In another report, lopinavir; ritonavir (400 mg; 100 mg PO twice daily for 14 days) increased the tenofovir (300 mg/day PO) Cmin 51% and AUC 32%, with no effect seen on lopinavir; ritonavir pharmacokinetics. While the clinical significance of this interaction is unknown, and is suspected to be insignificant, patients receiving lopinavir; ritonavir with tenofovir should be monitored for tenofovir-associated adverse events. [46638] Empagliflozin: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [7238] [7335] Empagliflozin; Linagliptin: (Moderate) Monitor for changes in glycemic control, specifically hyperglycemia, if ritonavir is administered concurrently with linagliptin. New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. [28315] [30575] [31240] [34557] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [7238] [7335] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy, such as linagliptin, should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [28341] [30575] Empagliflozin; Linagliptin; Metformin: (Moderate) Monitor for changes in glycemic control, specifically hyperglycemia, if ritonavir is administered concurrently with linagliptin. New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. [28315] [30575] [31240] [34557] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [7238] [7335] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy, such as linagliptin, should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [28341] [30575] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30480] [30575] Empagliflozin; Metformin: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [7238] [7335] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30480] [30575] Emtricitabine; Rilpivirine; Tenofovir alafenamide: (Major) Avoid coadministration of lopinavir with rilpivirine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Supratherapeutic doses of rilpivirine (75 to 300 mg/day) have caused QT prolongation. [28341] [44376] [65157] [65170] (Moderate) Concurrent use of lopinavir with tenofovir alafenamide may result in elevated tenofovir serum concentrations. Tenofovir alafenamide is a substrate for the drug transporter organic anion transporting polypeptide (OATP1B1/1B3); lopinavir is an OATP1B1 inhibitor. When 10 mg of tenofovir alafenamide was administered daily with lopinavir; ritonavir (800 mg/200 mg PO daily), the tenofovir Cmax and AUC increased by 2.19-fold and 1.47-fold, respectively. Monitor for increased toxicities if these drugs are given together. [60269] [61510] [61511] [61513] Emtricitabine; Rilpivirine; Tenofovir disoproxil fumarate: (Major) Avoid coadministration of lopinavir with rilpivirine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Supratherapeutic doses of rilpivirine (75 to 300 mg/day) have caused QT prolongation. [28341] [44376] [65157] [65170] (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrate, concurrently with inhibitors of P-gp and BCRP, such as ritonavir. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. [28193] [58664] (Minor) There are varying results in reports of an interaction between tenofovir and lopinavir; ritonavir. In one report, the concurrent administration of tenofovir with lopinavir; ritonavir increased tenofovir Cmax 31%, AUC 34%, and Cmin 29%, with slight (15%) decreases in lopinavir Cmax and AUC; the alterations may be a food effect rather than a drug-drug interaction. In another report, lopinavir; ritonavir (400 mg; 100 mg PO twice daily for 14 days) increased the tenofovir (300 mg/day PO) Cmin 51% and AUC 32%, with no effect seen on lopinavir; ritonavir pharmacokinetics. While the clinical significance of this interaction is unknown, and is suspected to be insignificant, patients receiving lopinavir; ritonavir with tenofovir should be monitored for tenofovir-associated adverse events. [46638] Emtricitabine; Tenofovir alafenamide: (Moderate) Concurrent use of lopinavir with tenofovir alafenamide may result in elevated tenofovir serum concentrations. Tenofovir alafenamide is a substrate for the drug transporter organic anion transporting polypeptide (OATP1B1/1B3); lopinavir is an OATP1B1 inhibitor. When 10 mg of tenofovir alafenamide was administered daily with lopinavir; ritonavir (800 mg/200 mg PO daily), the tenofovir Cmax and AUC increased by 2.19-fold and 1.47-fold, respectively. Monitor for increased toxicities if these drugs are given together. [60269] [61510] [61511] [61513] Emtricitabine; Tenofovir disoproxil fumarate: (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrate, concurrently with inhibitors of P-gp and BCRP, such as ritonavir. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. [28193] [58664] (Minor) There are varying results in reports of an interaction between tenofovir and lopinavir; ritonavir. In one report, the concurrent administration of tenofovir with lopinavir; ritonavir increased tenofovir Cmax 31%, AUC 34%, and Cmin 29%, with slight (15%) decreases in lopinavir Cmax and AUC; the alterations may be a food effect rather than a drug-drug interaction. In another report, lopinavir; ritonavir (400 mg; 100 mg PO twice daily for 14 days) increased the tenofovir (300 mg/day PO) Cmin 51% and AUC 32%, with no effect seen on lopinavir; ritonavir pharmacokinetics. While the clinical significance of this interaction is unknown, and is suspected to be insignificant, patients receiving lopinavir; ritonavir with tenofovir should be monitored for tenofovir-associated adverse events. [46638] Enalapril; Felodipine: (Moderate) Concurrent administration of felodipine with protease inhibitors may result in elevated felodipine plasma concentrations. This increase in felodipine concentration may lead to increased therapeutic and adverse effects, such as lower blood pressure, dizziness, and headache. Felodipine is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. In addition, ritonavir prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. [32432] [47165] Encainide: (Major) Concurrent administration of encainide with ritonavir may result in elevated encainide plasma concentrations. Encainide is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme and may increase serum encainide concentrations by as much as 2-fold. Because encainide has a narrow therapeutic index and adverse events may be severe, close monitoring and dose adjustment are advised if these drugs are administered together. [28315] [47165] [57084] [58664] Encorafenib: (Major) Avoid coadministration of encorafenib and ritonavir due to increased encorafenib exposure. If concurrent use cannot be avoided, reduce the encorafenib dose to one-third of the dose used prior to the addition of ritonavir. If ritonavir is discontinued, the original encorafenib dose may be resumed after 3 to 5 elimination half-lives of ritonavir. Encorafenib is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor with a single 50 mg dose of encorafenib (0.1 times the recommended dose) increased the encorafenib AUC and Cmax by 3-fold and 68%, respectively. [47165] [63317] (Major) Avoid coadministration of lopinavir with encorafenib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Encorafenib has been associated with dose-dependent QT prolongation. [28341] [63317] [65157] [65170] Enfortumab vedotin: (Moderate) Monitor for signs of enfortumab vedotin-related adverse reactions if coadministration with ritonavir is necessary. Concomitant use may increase free monomethyl auristatin E (MMAE) exposure, which may increase the incidence or severity of enfortumab-vedotin toxicities. MMAE, the microtubule-disrupting component of enfortumab vedotin, is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Clinical drug interaction studies have not been conducted for enfortumab vedotin. However, coadministration of another antibody-drug conjugate that contains MMAE with a strong CYP3A4 inhibitor increased the Cmax and AUC of MMAE by 25% and 34%, respectively, with no change in the total exposure of the antibody-drug conjugate. [34557] [64845] Entrectinib: (Major) Avoid coadministration of entrectinib with ritonavir due to increased entrectinib exposure resulting in increased treatment-related adverse effects. If coadministration cannot be avoided in adults and pediatric patients 12 years and older with BSA greater than 1.5 m2, reduce the entrectinib dose to 100 mg PO once daily. If ritonavir is discontinued, resume the original entrectinib dose after 3 to 5 elimination half-lives of ritonavir. Entrectinib is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor increased the AUC of entrectinib by 6-fold in a drug interaction study. [47165] [64567] (Major) Avoid coadministration of lopinavir with entrectinib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs have been associated with QT prolongation. [28341] [64567] [65157] [65170] Enzalutamide: (Severe) Coadministration of lopinavir with strong inducers of CYP3A4, such as enzalutamide, is contraindicated. Taking these drugs together could decrease lopinavir concentrations, and may lead to a reduction in antiretroviral activity. [28341] [51727] [56579] (Severe) Coadministration of ritonavir with enzalutamide is contraindicated as there is a potential for decreased ritonavir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Ritonavir is metabolized by CYP3A4; enzalutamide is a strong CYP3A4 inducer. [47165] [51727] Eplerenone: (Severe) Coadministration of ritonavir and eplerenone is contraindicated. Ritonavir potently inhibits the hepatic CYP3A4 isoenzyme and can increase the serum concentrations of eplerenone. Increased eplerenone concentrations may lead to a risk of developing hyperkalemia and hypotension. [27990] Erdafitinib: (Major) Avoid coadministration of erdafitinib and ritonavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If ritonavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor. [47165] [64064] Ergoloid Mesylates: (Severe) Coadministration of ergot alkaloids with potent inhibitors of CYP3A4, like anti-retroviral protease inhibitors is considered contraindicated due to the risk of acute ergot toxicity (e.g., vasospasm leading to cerebral ischemia, peripheral ischemia and/or other serious effects). Several case reports have established the clinical significance of this interaction in the medical literature. In some cases, fatal interactions have occurred. [28142] [28341] [28731] [28839] [28995] [32432] [46638] [5018] [5044] [5623] [5747] [8102] Ergonovine: (Severe) Coadministration of ergot alkaloids with potent inhibitors of CYP3A4, like anti-retroviral protease inhibitors is considered contraindicated due to the risk of acute ergot toxicity (e.g., vasospasm leading to cerebral ischemia, peripheral ischemia and/or other serious effects). Several case reports have established the clinical significance of this interaction in the medical literature. In some cases, fatal interactions have occurred. [28142] [28341] [28731] [28839] [28995] [32432] [46638] [5018] [5044] [5623] [5747] [8102] Ergot alkaloids: (Severe) Coadministration of ergot alkaloids with potent inhibitors of CYP3A4, like anti-retroviral protease inhibitors is considered contraindicated due to the risk of acute ergot toxicity (e.g., vasospasm leading to cerebral ischemia, peripheral ischemia and/or other serious effects). Several case reports have established the clinical significance of this interaction in the medical literature. In some cases, fatal interactions have occurred. [28142] [28341] [28731] [28839] [28995] [32432] [46638] [5018] [5044] [5623] [5747] [8102] Ergotamine: (Severe) Coadministration of ergot alkaloids with potent inhibitors of CYP3A4, like anti-retroviral protease inhibitors is considered contraindicated due to the risk of acute ergot toxicity (e.g., vasospasm leading to cerebral ischemia, peripheral ischemia and/or other serious effects). Several case reports have established the clinical significance of this interaction in the medical literature. In some cases, fatal interactions have occurred. [28142] [28341] [28731] [28839] [28995] [32432] [46638] [5018] [5044] [5623] [5747] [8102] Eribulin: (Major) Avoid coadministration of lopinavir with eribulin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs are associated with QT prolongation. [28341] [42449] [65157] [65170] Erlotinib: (Major) Avoid coadministration of erlotinib with ritonavir if possible due to the increased risk of erlotinib-related adverse reactions. If concomitant use is unavoidable and severe reactions occur, reduce the dose of erlotinib by 50 mg decrements. Erlotinib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased erlotinib exposure by 67%. [30555] [47165] Ertugliflozin; Metformin: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30480] [30575] Erythromycin: (Major) Avoid coadministration of lopinavir with erythromycin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Erythromycin is associated with QT prolongation and torsade de pointes (TdP). [28341] [43258] [65157] [65170] (Moderate) Caution is warranted with the use of erythromycin and ritonavir as erythromycin may increase ritonavir serum concentrations resulting in increased treatment-related adverse effects. Erythromycin inhibits CYP3A4 and P-glycoprotein (P-gp), while ritonavir is a substrate of both CYP3A4 and P-gp. [47165] [53544] Erythromycin; Sulfisoxazole: (Major) Avoid coadministration of lopinavir with erythromycin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Erythromycin is associated with QT prolongation and torsade de pointes (TdP). [28341] [43258] [65157] [65170] (Moderate) Caution is warranted with the use of erythromycin and ritonavir as erythromycin may increase ritonavir serum concentrations resulting in increased treatment-related adverse effects. Erythromycin inhibits CYP3A4 and P-glycoprotein (P-gp), while ritonavir is a substrate of both CYP3A4 and P-gp. [47165] [53544] Escitalopram: (Major) Avoid coadministration of lopinavir with escitalopram due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Escitalopram has been associated with a risk of QT prolongation and torsade de pointes (TdP). [28270] [28341] [65157] [65170] Eslicarbazepine: (Major) Concurrent administration of eslicarbazepine with ritonavir may result in decreased plasma concentrations of ritonavir. Eslicarbazepine is an inducer of the hepatic isoenzyme CYP3A4; ritonavir is metabolized by this enzyme. Caution and close monitoring for decreased antiviral efficacy are advised if these drugs are administered together. [56436] [58664] Esmolol: (Moderate) Ritonavir is expected to decrease the hepatic CYP metabolism of beta-blockers, resulting in increased beta-blocker concentrations. Cardiac and neurologic events have been reported when ritonavir is concurrently administered with beta-blockers. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including beta-blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased beta-blocker doses may be warranted. [5044] Esomeprazole: (Moderate) Concurrent administration of esomeprazole with ritonavir may result in elevated esomeprazole plasma concentrations. Esomeprazole is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Monitor patients for increased side effects if these drugs are administered together. [58664] [6265] Esomeprazole; Naproxen: (Moderate) Concurrent administration of esomeprazole with ritonavir may result in elevated esomeprazole plasma concentrations. Esomeprazole is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Monitor patients for increased side effects if these drugs are administered together. [58664] [6265] Estazolam: (Moderate) In vitro studies with human liver microsomes indicate that the biotransformation of estazolam to the major circulating metabolite 4-hydroxy-estazolam is mediated by CYP3A. In theory, CYP3A4 inhibitors, such as protease inhibitors, may reduce the metabolism of estazolam and increase the potential for benzodiazepine toxicity (i.e., prolonged sedation and respiratory depression) [30413] [32432] [46638] Esterified Estrogens: (Moderate) Ritonavir has been shown to increase the metabolism of ethinyl estradiol; a similar interaction may occur with other estrogens used for hormone replacement therapy. Patients should report any breakthrough bleeding or adverse events to their prescribers. [28315] [28341] Esterified Estrogens; Methyltestosterone: (Moderate) Ritonavir has been shown to increase the metabolism of ethinyl estradiol; a similar interaction may occur with other estrogens used for hormone replacement therapy. Patients should report any breakthrough bleeding or adverse events to their prescribers. [28315] [28341] Estradiol Cypionate; Medroxyprogesterone: (Major) Coadministration of medroxyprogesterone, a CYP3A substrate with ritonavir, a strong CYP3A inhibitor should be avoided since it is expected to increase concentrations of medroxyprogesterone acetate. Formal drug interaction studies have not been conducted; however, medroxyprogesterone is metabolized primarily by hydroxylation via the CYP3A4 in vitro. [28380] [34557] [47165] [57648] (Moderate) Ritonavir has been shown to increase the metabolism of ethinyl estradiol. Ritonavir is a substrate and inhibitor of CYP3A4. It is not known if the effects of protease inhibitors are similar on estradiol; however, estradiol is metabolized by CYP3A4, similar to ethinyl estradiol. [28315] Estradiol: (Moderate) Ritonavir has been shown to increase the metabolism of ethinyl estradiol. Ritonavir is a substrate and inhibitor of CYP3A4. It is not known if the effects of protease inhibitors are similar on estradiol; however, estradiol is metabolized by CYP3A4, similar to ethinyl estradiol. [28315] Estradiol; Levonorgestrel: (Major) Data on the effects that protease inhibitors have on the serum concentrations of estrogens and progestins are complex. Some protease inhibitors increase (i.e., ritonavir, lopinavir; ritonavir, nelfinavir, tipranavir) and others decrease (i.e., atazanavir, indinavir) the metabolism of hormonal contraceptives. The safety and efficacy of hormonal contraceptives may be affected if coadministered with protease inhibitors. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors concurrently should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with protease inhibitors to use an additional method of contraception to protect against unwanted pregnancy, unless other drug-specific recommendations are made by the manufacturer of the protease inhibitor. Furthermore, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with protease inhibitors should use an additional barrier method of contraception such as condoms. [46638] [5044] (Moderate) Ritonavir has been shown to increase the metabolism of ethinyl estradiol. Ritonavir is a substrate and inhibitor of CYP3A4. It is not known if the effects of protease inhibitors are similar on estradiol; however, estradiol is metabolized by CYP3A4, similar to ethinyl estradiol. [28315] Estradiol; Norethindrone: (Moderate) Many anti-retroviral protease inhibitors may interact with hormonal agents like norethindrone, due to their actions on CYP metabolism, particularly CYP3A4. Data on the effects that protease inhibitors have on the serum concentrations of norethindrone are complex and are based mostly off of data with norethindrone-containing contraceptives. For example, ritonavir (also found in combinations like lopinavir; ritonavir, and used as a booster in many HIV treatment regimens) may decrease the metabolism of norethindrone, raising norethindrone concentrations. Women receiving norethindrone for hormone replacement or contraception should report potential hormonal adverse effects (e.g., bleeding pattern changes, acne, emotional lability) or any changes in efficacy (e.g., noted changes in bleeding patterns) to their prescribers. Because norethindrone-containing contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive norethindrone contraception concurrently with ritonavir should use an additional barrier method of contraception such as condoms. [58679] [7731] (Moderate) Ritonavir has been shown to increase the metabolism of ethinyl estradiol. Ritonavir is a substrate and inhibitor of CYP3A4. It is not known if the effects of protease inhibitors are similar on estradiol; however, estradiol is metabolized by CYP3A4, similar to ethinyl estradiol. [28315] Estradiol; Norgestimate: (Moderate) Ritonavir has been shown to increase the metabolism of ethinyl estradiol. Ritonavir is a substrate and inhibitor of CYP3A4. It is not known if the effects of protease inhibitors are similar on estradiol; however, estradiol is metabolized by CYP3A4, similar to ethinyl estradiol. [28315] Estradiol; Progesterone: (Moderate) Ritonavir has been shown to increase the metabolism of ethinyl estradiol. Ritonavir is a substrate and inhibitor of CYP3A4. It is not known if the effects of protease inhibitors are similar on estradiol; however, estradiol is metabolized by CYP3A4, similar to ethinyl estradiol. [28315] (Moderate) Use caution if coadministration of ritonavir with progesterone is necessary, as the systemic exposure of progesterone may be increased resulting in an increase in treatment-related adverse reactions. Ritonavir is a strong CYP3A4 inhibitor. Progesterone is metabolized primarily by hydroxylation via a CYP3A4. This interaction does not apply to vaginal preparations of progesterone (e.g., Crinone, Endometrin). [47165] [63694] Estropipate: (Moderate) Ritonavir has been shown to increase the metabolism of ethinyl estradiol; a similar interaction may occur with other estrogens used for hormone replacement therapy. Patients should report any breakthrough bleeding or adverse events to their prescribers. [5044] [5070] Eszopiclone: (Major) The adult dose of eszopiclone should not exceed 2 mg/day during co-administration of potent CYP3A4 inhibitors, such as anti-retroviral protease inhibitors. CYP3A4 is a primary metabolic pathway for eszopiclone, and increased systemic exposure to eszopiclone increases the risk of next-day psychomotor or memory impairment, which may decrease the ability to perform tasks requiring full mental alertness such as driving. [30571] [31320] Ethanol: (Major) Concurrent administration of ethanol with ritonavir may result in decreased plasma concentrations of ritonavir, which may affect antiviral efficacy. Ethanol is an inducer of the hepatic isoenzyme CYP3A4; ritonavir is a substrate of this enzyme. Caution and close monitoring are advised if ethanol and ritonavir are administered together. [34760] [34761] [34762] [58664] Ethinyl Estradiol: (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] Ethinyl Estradiol; Desogestrel: (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] Ethinyl Estradiol; Ethynodiol Diacetate: (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] Ethinyl Estradiol; Etonogestrel: (Major) Coadministration may result in an increased or decreased effect of etonogestrel. Contraceptive efficacy may be reduced. Etonogestrel is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor and CYP3A4 inducer. [41597] [46375] [47165] (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] Ethinyl Estradiol; Levonorgestrel: (Major) Data on the effects that protease inhibitors have on the serum concentrations of estrogens and progestins are complex. Some protease inhibitors increase (i.e., ritonavir, lopinavir; ritonavir, nelfinavir, tipranavir) and others decrease (i.e., atazanavir, indinavir) the metabolism of hormonal contraceptives. The safety and efficacy of hormonal contraceptives may be affected if coadministered with protease inhibitors. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors concurrently should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with protease inhibitors to use an additional method of contraception to protect against unwanted pregnancy, unless other drug-specific recommendations are made by the manufacturer of the protease inhibitor. Furthermore, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with protease inhibitors should use an additional barrier method of contraception such as condoms. [46638] [5044] (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] Ethinyl Estradiol; Levonorgestrel; Ferrous bisglycinate: (Major) Data on the effects that protease inhibitors have on the serum concentrations of estrogens and progestins are complex. Some protease inhibitors increase (i.e., ritonavir, lopinavir; ritonavir, nelfinavir, tipranavir) and others decrease (i.e., atazanavir, indinavir) the metabolism of hormonal contraceptives. The safety and efficacy of hormonal contraceptives may be affected if coadministered with protease inhibitors. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors concurrently should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with protease inhibitors to use an additional method of contraception to protect against unwanted pregnancy, unless other drug-specific recommendations are made by the manufacturer of the protease inhibitor. Furthermore, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with protease inhibitors should use an additional barrier method of contraception such as condoms. [46638] [5044] (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] Ethinyl Estradiol; Levonorgestrel; Folic Acid; Levomefolate: (Major) Data on the effects that protease inhibitors have on the serum concentrations of estrogens and progestins are complex. Some protease inhibitors increase (i.e., ritonavir, lopinavir; ritonavir, nelfinavir, tipranavir) and others decrease (i.e., atazanavir, indinavir) the metabolism of hormonal contraceptives. The safety and efficacy of hormonal contraceptives may be affected if coadministered with protease inhibitors. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors concurrently should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with protease inhibitors to use an additional method of contraception to protect against unwanted pregnancy, unless other drug-specific recommendations are made by the manufacturer of the protease inhibitor. Furthermore, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with protease inhibitors should use an additional barrier method of contraception such as condoms. [46638] [5044] (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] Ethinyl Estradiol; Norelgestromin: (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] Ethinyl Estradiol; Norethindrone Acetate: (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] (Moderate) Many anti-retroviral protease inhibitors may interact with hormonal agents like norethindrone, due to their actions on CYP metabolism, particularly CYP3A4. Data on the effects that protease inhibitors have on the serum concentrations of norethindrone are complex and are based mostly off of data with norethindrone-containing contraceptives. For example, ritonavir (also found in combinations like lopinavir; ritonavir, and used as a booster in many HIV treatment regimens) may decrease the metabolism of norethindrone, raising norethindrone concentrations. Women receiving norethindrone for hormone replacement or contraception should report potential hormonal adverse effects (e.g., bleeding pattern changes, acne, emotional lability) or any changes in efficacy (e.g., noted changes in bleeding patterns) to their prescribers. Because norethindrone-containing contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive norethindrone contraception concurrently with ritonavir should use an additional barrier method of contraception such as condoms. [58679] [7731] Ethinyl Estradiol; Norethindrone Acetate; Ferrous fumarate: (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] (Moderate) Many anti-retroviral protease inhibitors may interact with hormonal agents like norethindrone, due to their actions on CYP metabolism, particularly CYP3A4. Data on the effects that protease inhibitors have on the serum concentrations of norethindrone are complex and are based mostly off of data with norethindrone-containing contraceptives. For example, ritonavir (also found in combinations like lopinavir; ritonavir, and used as a booster in many HIV treatment regimens) may decrease the metabolism of norethindrone, raising norethindrone concentrations. Women receiving norethindrone for hormone replacement or contraception should report potential hormonal adverse effects (e.g., bleeding pattern changes, acne, emotional lability) or any changes in efficacy (e.g., noted changes in bleeding patterns) to their prescribers. Because norethindrone-containing contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive norethindrone contraception concurrently with ritonavir should use an additional barrier method of contraception such as condoms. [58679] [7731] Ethinyl Estradiol; Norethindrone: (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] (Moderate) Many anti-retroviral protease inhibitors may interact with hormonal agents like norethindrone, due to their actions on CYP metabolism, particularly CYP3A4. Data on the effects that protease inhibitors have on the serum concentrations of norethindrone are complex and are based mostly off of data with norethindrone-containing contraceptives. For example, ritonavir (also found in combinations like lopinavir; ritonavir, and used as a booster in many HIV treatment regimens) may decrease the metabolism of norethindrone, raising norethindrone concentrations. Women receiving norethindrone for hormone replacement or contraception should report potential hormonal adverse effects (e.g., bleeding pattern changes, acne, emotional lability) or any changes in efficacy (e.g., noted changes in bleeding patterns) to their prescribers. Because norethindrone-containing contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive norethindrone contraception concurrently with ritonavir should use an additional barrier method of contraception such as condoms. [58679] [7731] Ethinyl Estradiol; Norethindrone; Ferrous fumarate: (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] (Moderate) Many anti-retroviral protease inhibitors may interact with hormonal agents like norethindrone, due to their actions on CYP metabolism, particularly CYP3A4. Data on the effects that protease inhibitors have on the serum concentrations of norethindrone are complex and are based mostly off of data with norethindrone-containing contraceptives. For example, ritonavir (also found in combinations like lopinavir; ritonavir, and used as a booster in many HIV treatment regimens) may decrease the metabolism of norethindrone, raising norethindrone concentrations. Women receiving norethindrone for hormone replacement or contraception should report potential hormonal adverse effects (e.g., bleeding pattern changes, acne, emotional lability) or any changes in efficacy (e.g., noted changes in bleeding patterns) to their prescribers. Because norethindrone-containing contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive norethindrone contraception concurrently with ritonavir should use an additional barrier method of contraception such as condoms. [58679] [7731] Ethinyl Estradiol; Norgestimate: (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] Ethinyl Estradiol; Norgestrel: (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] Ethosuximide: (Moderate) Ritonavir decreases the hepatic CYP metabolism of ethosuximide, resulting in increased ethosuximide concentrations. If coadministration is warranted, do so with caution and careful monitoring of ethosuximide concentrations. A 50% dose reduction of ethosuximide may be needed. [27896] [28001] [28315] [46638] Ethotoin: (Major) Concurrent use of ritonavir with ethotoin, phenytoin, or fosphenytoin should be avoided when possible. Increased doses of anticonvulsants may be required due to metabolism induction by ritonavir. Additionally, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [28315] [46638] Etonogestrel: (Major) Coadministration may result in an increased or decreased effect of etonogestrel. Contraceptive efficacy may be reduced. Etonogestrel is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor and CYP3A4 inducer. [41597] [46375] [47165] Etravirine: (Moderate) Concomitant use of etravirine with full-dose ritonavir (i.e., 600 mg twice daily) may cause a significant decrease in etravirine plasma concentration and, thus, a loss of therapeutic effect. Etravirine and full-dose ritonavir should not be coadministered. [33718] Everolimus: (Major) Avoid coadministration of ritonavir with everolimus (Afinitor; Afinitor Disperz) due to increased plasma concentrations of everolimus. Coadministration of ritonavir with everolimus (Zortress) is not recommended without close monitoring of everolimus whole blood trough concentrations. Everolimus is a CYP3A4 substrate as well as a substrate of P-glycoprotein (P-gp); ritonavir is a strong inhibitor of CYP3A4 and a P-gp inhibitor. Coadministration with another strong CYP3A4/P-gp inhibitor increased everolimus exposure by 15-fold. [28380] [34557] [47165] [49598] [49823] Ezetimibe; Simvastatin: (Severe) The coadministration of anti-retroviral protease inhibitors with simvastatin is contraindicated. Taking these drugs together may significantly increase the serum concentration of simvastatin; thereby increasing the risk of myopathy and rhabdomyolysis. One report has demonstrated that ritonavir plus saquinavir therapy markedly increases the AUC for simvastatin by 3059%. Simvastatin is a substrate for CYP3A4 and the drug transporter organic anion transporting polypeptide (OATP1B1); protease inhibitors are CYP3A4 and OATP inhibitors. [28605] [39682] [46638] [61510] [61511] [61512] [61513] Ezogabine: (Major) Avoid coadministration of lopinavir with ezogabine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs have been associated with QT prolongation. [28341] [44800] [65157] [65170] Fedratinib: (Major) Avoid coadministration of fedratinib with ritonavir as concurrent use may increase fedratinib exposure. If concurrent use cannot be avoided, reduce the dose of fedratinib to 200 mg PO once daily. If ritonavir is discontinued, increase the fedratinib dose as follows: 300 mg PO once daily for 2 weeks and then 400 mg PO once daily thereafter as tolerated. Fedratinib is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased fedratinib exposure by 3-fold. [28315] [64568] Felbamate: (Major) Concurrent administration of felbamate with ritonavir may result in decreased plasma concentrations of ritonavir. Felbamate is a mild inducer of the hepatic isoenzyme CYP3A4; ritonavir is metabolized by this enzyme. Monitor for antiviral efficacy if these drugs are administered together. [4190] [58664] Felodipine: (Moderate) Concurrent administration of felodipine with protease inhibitors may result in elevated felodipine plasma concentrations. This increase in felodipine concentration may lead to increased therapeutic and adverse effects, such as lower blood pressure, dizziness, and headache. Felodipine is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. In addition, ritonavir prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. [32432] [47165] Fentanyl: (Major) Consider a reduced dose of fentanyl with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. If ritonavir is discontinued, consider increasing the fentanyl dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Fentanyl is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase fentanyl exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of fentanyl. If ritonavir is discontinued, fentanyl plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to fentanyl. Clinical investigations have suggested that ritonavir may decrease the clearance of fentanyl by 67%, increase the elimination half-life from 9.4 to 20.1 hours, and increase the systemic exposure of fentanyl by 174% (range: 52 to 420%). [26403] [29623] [29763] [32731] [40943] [47165] Fesoterodine: (Moderate) Fesoterodine is rapidly hydrolyzed to its active metabolite, 5-hydroxymethyltolterodine, which is metabolized via hepatic CYP3A4 and 2D6. In theory, the CYP3A4 inhibitory effects of anti-retroviral protease inhibitors may result in an increase in plasma concentrations of 5-hydroxymethyltolterodine. Anti-retroviral protease inhibitors which also inhibit 2D6, such as ritonavir, may impair both CYP metabolic pathways of 5-hydroxymethyltolterodine. Fesoterodine doses greater than 4 mg/day are not recommended during concurrent use of potent 3A4 inhibitors. [11397] Fexofenadine: (Moderate) Monitor for fexofenadine-related adverse reactions during concurrent administration with lopinavir as use of these drugs together may increase exposure of fexofenadine. Fexofenadine is a substrate of the organic anion transporting peptide (OATP1B1); lopinavir inhibits OATP1B1. [28341] [56579] [61510] [61511] [61513] (Minor) The plasma concentrations of fexofenadine may be elevated when administered concurrently with ritonavir. Clinical monitoring for adverse effects, such as drowsiness, is recommended during coadministration. Ritonavir is a P-glycoprotein (P-gp) inhibitor, while fexofenadine is a P-gp substrate. [28380] [34526] [34527] [47165] Fexofenadine; Pseudoephedrine: (Moderate) Monitor for fexofenadine-related adverse reactions during concurrent administration with lopinavir as use of these drugs together may increase exposure of fexofenadine. Fexofenadine is a substrate of the organic anion transporting peptide (OATP1B1); lopinavir inhibits OATP1B1. [28341] [56579] [61510] [61511] [61513] (Minor) The plasma concentrations of fexofenadine may be elevated when administered concurrently with ritonavir. Clinical monitoring for adverse effects, such as drowsiness, is recommended during coadministration. Ritonavir is a P-glycoprotein (P-gp) inhibitor, while fexofenadine is a P-gp substrate. [28380] [34526] [34527] [47165] Fingolimod: (Major) If possible, avoid coadministration of lopinavir; ritonavir and fingolimod. If concomitant use cannot be avoided, overnight monitoring with continuous ECG in a medical facility after the first fingolimod dose is advised. Fingolimod has not been studied in patients treated with drugs that prolong the QT interval, but drugs that prolong the QT interval have been associated with cases of torsade de pointes in patients with bradycardia. Lopinavir; ritonavir is associated with a possible risk for QT prolongation and torsade de pointes (TdP) based on varying levels of documentation. Fingolimod initiation results in decreased heart rate and may prolong the QT interval. Fingolimod is contraindicated for use by patients with a baseline QTc interval >= 500 msec. [28341] [41823] Flecainide: (Major) Concurrent use of HIV treatment doses of ritonavir with flecainide is contraindicated. Cautious consideration may be given to administering amiodarone with boosting doses of ritonavir. The potential increase in plasma concentrations of flecainide could result in significant adverse effects. [47165] (Major) Due to the potential for QT prolongation and torsade de pointes (TdP), caution is advised when administering lopinavir; ritonavir with flecainide. Lopinavir; ritonavir is associated with QT prolongation. Flecainide is a Class IC antiarrhythmic associated with a possible risk for QT prolongation and/or TdP; flecainide increases the QT interval, but largely due to prolongation of the QRS interval. Although causality for TdP has not been established for flecainide, patients receiving concurrent drugs which have the potential for QT prolongation may have an increased risk of developing proarrhythmias. [23774] [28341] [28752] Flibanserin: (Severe) The concomitant use of flibanserin and strong CYP3A4 inhibitors, such as ritonavir, is contraindicated. Strong CYP3A4 inhibitors can increase flibanserin concentrations, which can cause severe hypotension and syncope. If initiating flibanserin following use of a strong CYP3A4 inhibitor, start flibanserin at least 2 weeks after the last dose of the CYP3A4 inhibitor. If initiating a strong CYP3A4 inhibitor following flibanserin use, start the strong CYP3A4 inhibitor at least 2 days after the last dose of flibanserin. [60099] Fluconazole: (Major) Avoid coadministration of lopinavir with fluconazole due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Fluconazole has been associated with QT prolongation and rare cases of torsade de pointes (TdP). Based on metabolic profiles, clinically significant pharmacokinetic drug interactions are not expected. [28341] [28674] [65157] [65170] (Moderate) Caution is warranted with the use of fluconazole and ritonavir as ritonavir serum concentrations may be increased resulting in increased treatment-related adverse effects. Fluconazole is a moderate CYP3A4 inhibitor, while ritonavir is a substrate of CYP3A4. [28315] [28674] Fluoxetine: (Major) Avoid coadministration of lopinavir with fluoxetine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. QT prolongation and torsade de pointes (TdP) have been reported in patients treated with fluoxetine. [28341] [65157] [65170] (Moderate) A dose reduction of fluoxetine may ne necessary if coadministered with ritonavir. Increased fluoxetine exposure may occur. Cardiac and neurologic events have been reported when ritonavir has been administered with fluoxetine. [47165] Fluoxetine; Olanzapine: (Major) Avoid coadministration of lopinavir with fluoxetine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. QT prolongation and torsade de pointes (TdP) have been reported in patients treated with fluoxetine. [28341] [65157] [65170] (Major) Avoid coadministration of lopinavir with olanzapine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Limited data, including some case reports, suggest that olanzapine may be associated with a significant prolongation of the QTc interval. [28341] [28785] [32732] [32734] [32745] [32746] [65157] [65170] (Moderate) A dose reduction of fluoxetine may ne necessary if coadministered with ritonavir. Increased fluoxetine exposure may occur. Cardiac and neurologic events have been reported when ritonavir has been administered with fluoxetine. [47165] (Moderate) Ritonavir may reduce olanzapine serum concentrations by approximately 50%; how this affects olanzapine efficacy, however, is not known. Ritonavir appears to induce olanzapine's metabolism by either CYP1A2 or glucuronide conjugation. If ritonavir and olanzapine are used concurrently, monitor for reduced olanzapine effect and adjust olanzapine dose as needed. [27275] Fluphenazine: (Major) Avoid coadministration of lopinavir with fluphenazine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Fluphenazine is associated with a possible risk for QT prolongation. [28341] [28415] [65157] [65170] Flurazepam: (Major) CYP3A4 inhibitors, such as protease inhibitors, may reduce the metabolism of flurazepam and increase the potential for benzodiazepine toxicity. A decrease in the flurazepam dose may be needed. [28001] [28345] [32432] Fluticasone: (Major) Coadministration of inhaled fluticasone propionate and ritonavir is not recommended; use caution with inhaled fluticasone furoate. During post-marketing use, there have been reports of clinically significant drug interactions in patients receiving inhaled fluticasone propionate with ritonavir, resulting in systemic corticosteroid effects including Cushing's syndrome and adrenal suppression. Fluticasone is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. In a drug interaction study, coadministration with ritonavir increased plasma fluticasone propionate exposure resulting in an 86% decrease in serum cortisol AUC. Another strong inhibitor increased fluticasone furoate exposure by 1.33-fold with a 27% reduction in weighted mean serum cortisol; this change does not necessitate dose adjustment of fluticasone furoate. [40360] [40475] [43972] [57805] Fluticasone; Salmeterol: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] (Major) Avoid coadministration of salmeterol with ritonavir. The coadministration of salmeterol with CYP3A4 inhibitors can result in elevated salmeterol plasma concentrations and increased risk for adverse reactions, particularly cardiovascular effects. [28315] [28467] [47165] (Major) Coadministration of inhaled fluticasone propionate and ritonavir is not recommended; use caution with inhaled fluticasone furoate. During post-marketing use, there have been reports of clinically significant drug interactions in patients receiving inhaled fluticasone propionate with ritonavir, resulting in systemic corticosteroid effects including Cushing's syndrome and adrenal suppression. Fluticasone is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. In a drug interaction study, coadministration with ritonavir increased plasma fluticasone propionate exposure resulting in an 86% decrease in serum cortisol AUC. Another strong inhibitor increased fluticasone furoate exposure by 1.33-fold with a 27% reduction in weighted mean serum cortisol; this change does not necessitate dose adjustment of fluticasone furoate. [40360] [40475] [43972] [57805] Fluticasone; Umeclidinium; Vilanterol: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] (Major) Coadministration of inhaled fluticasone propionate and ritonavir is not recommended; use caution with inhaled fluticasone furoate. During post-marketing use, there have been reports of clinically significant drug interactions in patients receiving inhaled fluticasone propionate with ritonavir, resulting in systemic corticosteroid effects including Cushing's syndrome and adrenal suppression. Fluticasone is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. In a drug interaction study, coadministration with ritonavir increased plasma fluticasone propionate exposure resulting in an 86% decrease in serum cortisol AUC. Another strong inhibitor increased fluticasone furoate exposure by 1.33-fold with a 27% reduction in weighted mean serum cortisol; this change does not necessitate dose adjustment of fluticasone furoate. [40360] [40475] [43972] [57805] Fluticasone; Vilanterol: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] (Major) Coadministration of inhaled fluticasone propionate and ritonavir is not recommended; use caution with inhaled fluticasone furoate. During post-marketing use, there have been reports of clinically significant drug interactions in patients receiving inhaled fluticasone propionate with ritonavir, resulting in systemic corticosteroid effects including Cushing's syndrome and adrenal suppression. Fluticasone is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. In a drug interaction study, coadministration with ritonavir increased plasma fluticasone propionate exposure resulting in an 86% decrease in serum cortisol AUC. Another strong inhibitor increased fluticasone furoate exposure by 1.33-fold with a 27% reduction in weighted mean serum cortisol; this change does not necessitate dose adjustment of fluticasone furoate. [40360] [40475] [43972] [57805] Fluvastatin: (Moderate) Monitor for fluvastatin-related adverse reactions (myopathy, rhabdomyolysis) during concurrent administration with lopinavir as use of these drugs together may increase fluvastatin exposure. Fluvastatin is a substrate of the organic anion transporting peptide (OATP1B1); lopinavir inhibits OATP1B1. [28341] [36451] [45527] [56579] [61510] [61511] [61513] (Moderate) Ritonavir is an inhibitor of CYP3A4 and may increase exposure to drugs metabolized by this enzyme, such as fluvastatin. Because fluvastatin does not rely exclusively on CYP3A4 for its metabolism (approximately 20%), ritonavir may not interact to the same extent as expected with other HMG-CoA reductase inhibitors. Elevated serum concentrations of fluvastatin may increase the risk for adverse reactions, such as myopathy. [28774] [45527] [58664] Fluvoxamine: (Major) Avoid coadministration of lopinavir with fluvoxamine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. QT prolongation and torsade de pointes (TdP) has been reported with postmarketing use of fluvoxamine. [28341] [50507] [65157] [65170] (Moderate) Concurrent administration of fluvoxamine with ritonavir may result in increased plasma concentrations of one or both drugs. Fluvoxamine is partially metabolized by CYP2D6 and ritonavir is a weak CYP2D6 inhibitor. In addition, ritonavir is metabolized by CYP3A4, and fluvoxamine is a moderate CYP3A4 inhibitor. Caution and close monitoring are advised if these drugs are administered together. [47165] [50507] Food: (Moderate) The pharmacokinetic parameters of anti-retroviral medications (anti-retroviral non-nucleoside reverse transcriptase inhibitors (NNRTIs), anti-retroviral nucleoside reverse transcriptase inhibitors (NRTIs), anti-retroviral nucleotide reverse transcriptase inhibitors, and anti-retroviral protease inhibitors) metabolized through the CYP isoenzyme system are slightly altered by smoked and oral marijuana. Despite this interaction, marijuana is not expected to adversely affect anti-retroviral efficacy. However, the incidence of marijuana associated adverse effects may change following coadministration with anti-retroviral drugs. Many anti-retrovirals are inhibitors of CYP3A4, an isoenzyme partially responsible for the metabolism of marijuana's most psychoactive compound, delta-9-tetrahydrocannabinol (Delta-9-THC). When given concurrently with anti-retrovirals, the amount of Delta-9-THC converted to the active metabolite 11-hydroxy-delta-9-tetrahydrocannabinol (11-OH-THC) may be reduced. These changes in Delta-9-THC and 11-OH-THC plasma concentrations may result in an altered marijuana adverse event profile. [42135] [42294] [42448] Formoterol: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] Formoterol; Mometasone: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] (Moderate) Coadministration of mometasone with ritonavir (a strong CYP3A4 inhibitor) may cause mometasone serum concentrations to increase, potentially resulting in Cushing's syndrome and adrenal suppression. Consider use of an alternative corticosteroid whose concentrations are less affected by strong CYP3A4 inhibitors, such as beclomethasone and prednisolone, especially during long-term treatment. [28341] [47165] [58620] Fosamprenavir: (Major) The coadministration of fosamprenavir (twice daily, boosted with ritonavir) and lopinavir; ritonavir tablets (400/100 mg) resulted in altered pharmacokinetics of both drugs in addition to an increased rate of adverse events. Decreases were seen in the fosamprenavir Cmax (by 58%), AUC (by 63%), and Cmin (by 65%). Increases were seen in the lopinavir; ritonavir (400/100 mg) Cmax (by 30%), AUC (by 37%), and Cmin (by 52%). The coadministration of fosamprenavir (1400 mg twice daily) and lopinavir; ritonavir (533/133 mg twice daily) resulted in decreased fosamprenavir Cmax (by 13%), AUC (by 26%), and Cmin (by 42%), in addition to an increased rate of adverse events. With respect to safety and efficacy, appropriate doses of fosamprenavir and lopinavir; ritonavir, when used in combination, have not been established. [28341] [29012] [46638] Foscarnet: (Major) Avoid coadministration of lopinavir with foscarnet due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Both QT prolongation and torsade de pointes (TdP) have been reported during postmarketing use of foscarnet. [28341] [28377] [65157] [65170] (Moderate) Abnormal renal function has been observed in clinical practice during the use of foscarnet in combination with ritonavir. If these drugs are administered together, monitor kidney function. [28377] [47165] Fosphenytoin: (Major) Concurrent use of ritonavir with ethotoin, phenytoin, or fosphenytoin should be avoided when possible. Increased doses of anticonvulsants may be required due to metabolism induction by ritonavir. Additionally, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [28315] [46638] Fostamatinib: (Moderate) Monitor for fostamatinib toxicities that may require fostamatinib dose reduction (i.e., elevated hepatic enzymes, neutropenia, high blood pressure, severe diarrhea) if given concurrently with a strong CYP3A4 inhibitor. Concomitant use of fostamatinib with a strong CYP3A4 inhibitor increases exposure to the major active metabolite, R406, which may increase the risk of adverse reactions. R406 is extensively metabolized by CYP3A4; ritonavir is a strong CYP3A4 inhibitor. Coadministration of fostamatinib with another strong CYP3A4 inhibitor increased R406 AUC by 102% and Cmax by 37%. [47165] [63084] Fostemsavir: (Major) Avoid coadministration of lopinavir with fostemsavir due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Supratherapeutic doses of fostemsavir (2,400 mg twice daily, four times the recommended daily dose) have been shown to cause QT prolongation. Fostemsavir causes dose-dependent QT prolongation. [28341] [65157] [65170] [65666] Gefitinib: (Moderate) Monitor for an increase in gefitinib-related adverse reactions if coadministration with ritonavir is necessary. Gefitinib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased gefitinib exposure by 80%. [28341] [45935] [47165] [56579] Gemifloxacin: (Major) Avoid coadministration of lopinavir with gemifloxacin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Gemifloxacin may prolong the QT interval in some patients. The maximal change in the QTc interval occurs approximately 5 to 10 hours following oral administration of gemifloxacin. [28341] [28419] [28420] [28424] [65157] [65170] Gemtuzumab Ozogamicin: (Major) Avoid coadministration of lopinavir with gemtuzumab due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Although QT interval prolongation has not been reported with gemtuzumab, it has been reported with other drugs that contain calicheamicin. [28341] [62292] [65157] [65170] Gilteritinib: (Major) Avoid coadministration of lopinavir with gilteritinib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Both drugs have been associated with QT prolongation. [28341] [63787] [65157] [65170] (Major) Consider an alternative to ritonavir during treatment with gilteritinib. Concurrent use may increase gilteritinib exposure resulting in treatment-related adverse events. If coadministration is required, frequently monitor for gilteritinib adverse reactions. Interrupt therapy and reduce the gilteritinib dose if serious or life-threatening toxicity occurs. Gilteritinib is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor increased the gilteritinib AUC by 120% in a drug interaction study. [47165] [63787] Glasdegib: (Major) Avoid coadministration of lopinavir with glasdegib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Glasdegib therapy may result in QT prolongation and ventricular arrhythmias including ventricular fibrillation and ventricular tachycardia. [28341] [63777] [65157] [65170] (Major) Consider an alternative to ritonavir during treatment with glasdegib. Concurrent use may increase glasdegib exposure resulting in treatment-related adverse events including QT prolongation. If coadministration cannot be avoided, monitor for increased adverse events; more frequent ECG monitoring is recommended. Glasdegib is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor increased the glasdegib AUC by 2.4-fold in a drug interaction study. [47165] [63777] Glecaprevir; Pibrentasvir: (Major) Coadministration of glecaprevir with lopinavir is not recommended as coadministration may increase serum concentrations of glecaprevir and increase the risk of adverse effects. Glecaprevir is a substrate of the organic anion transporting protein (OATP1B1); lopinavir is an inhibitor of OATP1B1. In drug interaction studies, coadministration of lopinavir; ritonavir with glecaprevir; pibrentasvir resulted in an approximately 4-fold increase in the AUC of glecaprevir. [28341] [56579] [62201] (Major) Coadministration of glecaprevir with ritonavir is not recommended as coadministration may increase serum concentrations of glecaprevir and increase the risk of adverse effects. Glecaprevir is a substrate of CYP3A4 and P-glycoprotein (P-gp); ritonavir is an inhibitor of CYP3A4 and P-gp. Additionally, ritonavir is a P-gp substrate and glecaprevir is a P-gp inhibitor; concentrations of ritonavir may also be increased. [28380] [34557] [62201] (Major) Coadministration of pibrentasvir with ritonavir is not recommended as coadministration may increase serum concentrations of pibrentasvir and increase the risk of adverse effects. Pibrentasvir is a substrate of the drug transporter P-glycoprotein (P-gp); ritonavir is an inhibitor of P-gp. Additionally, ritonavir is a P-gp substrate and pibrentasvir is a P-gp inhibitor; concentrations of ritonavir may also be increased. [28380] [34557] [62201] Glipizide; Metformin: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30480] [30575] Glyburide; Metformin: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30480] [30575] Glycopyrrolate; Formoterol: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] Goserelin: (Major) Avoid coadministration of lopinavir with goserelin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Androgen deprivation therapy (i.e., goserelin) may prolong the QT/QTc interval. [28341] [28592] [65157] [65170] Granisetron: (Major) Avoid coadministration of lopinavir with granisetron due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs have been associated with QT prolongation. [28341] [31723] [65157] [65170] (Minor) Plasma concentrations of granisetron may be elevated when administered concurrently with ritonavir. Clinical monitoring for adverse effects, such as gastrointestinal or CNS effects, is recommended during coadministration. Ritonavir is a CYP3A4 inhibitor; granisetron is a CYP3A4 substrate. [28315] [31723] [47165] Grapefruit juice: (Moderate) Concurrent administration of ritonavir with grapefruit juice may result in elevated ritonavir concentrations. Grapefruit juice is an inhibitor of the hepatic isoenzymes CYP3A4 and CYP2D6, and an inhibitor of the drug transporter P-glycoprotein (P-gp). Ritonavir is metabolized by both enzymes and is a substrate for P-gp. Caution and close monitoring are advised if these drugs are administered together. [58664] Griseofulvin: (Major) Oral solutions of lopinavir; ritonavir contain ethanol. Administration of lopinavir; ritonavir oral solution to patients receiving or who have recently received griseofulvin may result in disulfiram-like reactions (e.g., abdominal cramps, nausea/vomiting, headaches, and flushing). A disulfiram reaction would not be expected to occur with non-ethanol containing formulations of lopinavir; ritonavir (e.g., tablets). [28341] [29964] [65243] (Major) Ritonavir oral solution and capsules contain ethanol. Administration of ritonavir oral solution and capsules to patients receiving or who have recently received griseofulvin may result in disulfiram-like reactions (e.g., abdominal cramps, nausea/vomiting, headaches, and flushing). A disulfiram reaction would not be expected to occur with non-ethanol containing formulations of ritonavir (e.g., tablets or oral powder). [28315] [29964] [65243] Guaifenesin; Hydrocodone: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Guaifenesin; Hydrocodone; Pseudoephedrine: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Guanfacine: (Major) Ritonavir may significantly alter guanfacine plasma concentrations. Guanfacine is primarily metabolized by CYP3A4. Ritonavir is a potent CYP3A4 inhibitor; moderate CYP3A4 induction has been reported with concomitant use of voriconazole. The net effect of this potential interaction is unclear, but guanfacine dosage adjustments, most likely a dose decrease, may be required. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if used with a moderate to strong CYP3A4 inhibitor, the guanfacine dosage should be decreased to half of the recommended dose and the patient should be closely monitored for alpha-adrenergic effects (e.g., hypotension, drowsiness, bradycardia). However, if used with a moderate to strong CYP3A4 inducer, labeling recommends to consider doubling the recommended dose of guanfacine ER; if the inducer is added in a patient already receiving guanfacine, this escalation should occur over 1 to 2 weeks. If the inducer or inhibitor is discontinued, guanfacine ER should return to its recommended dose (with downward titration occurring over 1 to 2 weeks). Specific recommendations for immediate-release (IR) guanfacine are not available. [27493] [43566] [47165] Halofantrine: (Moderate) Protease Inhibitors significantly inhibit cytochrome CYP3A4,and may lead to an inhibition of halofantrine metabolism, placing the patient at risk for halofantrine cardiac toxicity. [4718] [4968] Halogenated Anesthetics: (Major) Avoid coadministration of lopinavir with halogenated anesthetics due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir and halogenated anesthetics can both prolong the QT interval. [28341] [28457] [28458] [28754] [28755] [28756] [65157] [65170] Haloperidol: (Major) Avoid coadministration of lopinavir with haloperidol due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. QT prolongation and torsade de pointes (TdP) have been observed during haloperidol treatment. Excessive doses (particularly in the overdose setting) or IV administration of haloperidol may be associated with a higher risk of QT prolongation. [23500] [23779] [28307] [28341] [28415] [65157] [65170] (Moderate) Mild to moderate increases in haloperidol plasma concentrations have been reported during concurrent use of haloperidol and inhibitors of CYP3A4 or CYP2D6, such as ritonavir. Elevated haloperidol concentrations may increase the risk of adverse effects. Closely monitor for adverse events when these medications are coadministered. [28307] [47165] Histrelin: (Major) Avoid coadministration of lopinavir with histrelin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Androgen deprivation therapy (i.e., histrelin) may prolong the QT/QTc interval. [28341] [30369] [65157] [65170] Homatropine; Hydrocodone: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Hydantoins: (Major) Concurrent use of lopinavir and hydantoins should be avoided when possible. Coadministration results in decreased plasma concentrations of both lopinavir and the hydantoin. If these drugs are given together, the once daily regimen of lopinavir should not be administered. Also, phenytoin concentrations should be monitored closely during concurrent administration with lopinavir. [28341] [46638] (Major) Concurrent use of ritonavir with ethotoin, phenytoin, or fosphenytoin should be avoided when possible. Increased doses of anticonvulsants may be required due to metabolism induction by ritonavir. Additionally, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [28315] [46638] Hydrochlorothiazide, HCTZ; Losartan: (Moderate) Concurrent administration of losartan with ritonavir may result in elevated losartan plasma concentrations. Losartan is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [47165] [5339] [58664] Hydrochlorothiazide, HCTZ; Metoprolol: (Moderate) Metoprolol is significantly metabolized by CYP2D6 isoenzymes. CYP2D6 inhibitors, such as ritonavir, may impair metoprolol metabolism. Clinicians should be alert to exaggerated beta-blocker effects if metoprolol is given with these drugs. [5044] [5269] Hydrochlorothiazide, HCTZ; Propranolol: (Moderate) Concurrent administration of propranolol with ritonavir may result in elevated propranolol plasma concentrations. Cardiac and neurologic events have been reported when ritonavir is concurrently administered with beta-blockers. Propranolol is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. Decreased beta-blocker dosage may be needed. [28315] [47165] [4998] [58664] Hydrochlorothiazide, HCTZ; Valsartan: (Moderate) Concurrent use of lopinavir with valsartan may result in elevated valsartan serum concentrations. Valsartan is a substrate for the drug transporter organic anion transporting polypeptide (OATP1B1/1B3); lopinavir is an OATP1B1 inhibitor. Monitor for increased toxicities if these drugs are given together. [56579] [61510] [61511] [61513] (Minor) Valsartan is a substrate of the hepatic efflux transporter MRP2 and ritonavir is an inhibitor of MRP2. Coadministration may increase systemic exposure to valsartan. Patients should be monitored for adverse effects of valsartan during coadministration. [28315] [29130] [36646] [39870] [60860] Hydrocodone: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Hydrocodone; Ibuprofen: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Hydrocodone; Phenylephrine: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Hydrocodone; Potassium Guaiacolsulfonate: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Hydrocodone; Potassium Guaiacolsulfonate; Pseudoephedrine: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Hydrocodone; Pseudoephedrine: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like ritonavir can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced in patients also receiving a CYP2D6 inhibitor. If ritonavir is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. [30379] [30391] [47165] [56303] [58531] Hydroxychloroquine: (Major) Avoid coadministration of hydroxychloroquine and lopinavir due the risk of additive QT prolongation. If use together is necessary, obtain an ECG at baseline to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Hydroxychloroquine prolongs the QT interval. Lopinavir is also associated with QT prolongation. [28341] [41806] [65157] [65170] Hydroxyzine: (Major) Avoid coadministration of lopinavir with hydroxyzine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Postmarketing data indicate that hydroxyzine causes QT prolongation and torsade de pointes (TdP). [28341] [47129] [65157] [65170] Ibrutinib: (Major) Avoid the concomitant use of ibrutinib and ritonavir; ibrutinib plasma concentrations may increase resulting in severe ibrutinib toxicity (e.g., hematologic toxicity, bleeding, infection). Ibrutinib is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. When ibrutinib was administered with multiple doses of other strong CYP3A4 inhibitors, the Cmax and AUC values of ibrutinib were increased significantly. [47165] [56410] Ibuprofen; Oxycodone: (Moderate) Consider a reduced dose of oxycodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. If ritonavir is discontinued, consider increasing the oxycodone dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oxycodone is a CYP3A4 substrate, and coadministration with a strong CYP3A4 inhibitor like ritonavir can increase oxycodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of oxycodone. If ritonavir is discontinued, oxycodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to oxycodone. [39926] [47165] Ibutilide: (Major) Avoid coadministration of lopinavir with ibutilide due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Ibutilide administration can cause QT prolongation and torsade de pointes (TdP); proarrhythmic events should be anticipated. [28341] [41830] [65157] [65170] Idelalisib: (Severe) Concomitant use of idelalisib, a CYP3A4 substrate, and ritonavir, a strong CYP3A4 inhibitor, may increase the exposure of idelalisib. Additionally, idelalisib is a strong CYP3A inhibitor while ritonavir is a CYP3A substrate. The AUC of a sensitive CYP3A substrate was increased 5.4-fold when coadministered with idelalisib. Avoid concomitant use of idelalisib and ritonavir. [5070] [57675] (Moderate) Avoid concurrent use of idelalisib and lopinavir when possible. Use of idelalisib, a strong CYP3A4 inhibitor, and lopinavir, a CYP3A4 substrate, may increase lopinavir plasma concentrations. The AUC of a sensitive CYP3A substrate was increased 5.4-fold when coadministered with idelalisib. [28341] [57675] Ifosfamide: (Moderate) Monitor for a decrease in the efficacy of ifosfamide if coadministration with ritonavir is necessary. Ifosfamide is metabolized by CYP3A4 to its active alkylating metabolites. Ritonavir is a strong CYP3A4 inhibitor. Coadministration may decrease plasma concentrations of these active metabolites, decreasing the effectiveness of ifosfamide treatment. [47165] [51027] Iloperidone: (Major) Avoid coadministration of lopinavir with iloperidone due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs have been associated with QT prolongation. [28341] [36146] [65157] [65170] (Major) Reduce the iloperidone dose by one-half if coadministered with ritonavir. If ritonavir is discontinued, increase the iloperidone dose to the previous level. Increased iloperidone exposure may occur with concurrent use. Iloperidone is a CYP3A4 substrate. Ritonavir is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased the AUC of iloperidone and its metabolites P88 and P95 by 57%, 55% and 35%, respectively. [36146] [47165] Imatinib: (Major) Protease Inhibitors inhibit cytochrome P450 CYP3A4 and may decrease the metabolism of imatinib and increase imatinib concentrations leading to an increased incidence of adverse reactions. In addition, because imatinib inhibits CYP2C9, CYP2D6, and CYP3A4/5, the metabolism of protease inhibitors may be decreased by imatinib. Close monitoring of the antiviral and antineoplastic responses is recommended. [28240] [28341] Imipramine: (Moderate) A dose reduction of the tricyclic antidepressant (TCA) may be necessary when coadministered with ritonavir. Concurrent use may result in elevated TCA plasma concentrations. [47165] Incretin Mimetics: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of protease inhibitors. Patients taking antidiabetic agents should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30575] [50113] [50814] Indacaterol: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] (Moderate) Although no dosage adjustment of the 75 mcg indacaterol daily dose is needed, use caution if indacaterol and ritonavir are used concurrently. Monitor the patient clinically for beta-agonist side effects like tremor, nervousness, or fast, irregular heart rate. In addition, both ritonavir and long-acting beta agonists (LABAs) are associated with QT prolongation; concomitant use may increase the risk of QT prolongation. By inhibiting CYP3A4, CYP2D6, and P-glycoprotein, ritonavir reduces indacaterol metabolism. In drug interaction studies, coadministration of indacaterol 300 mcg (single dose) with ritonavir (300 mg twice daily for 7.5 days) resulted in a 1.7-fold increase in indacaterol exposure (AUC) whereas indacaterol maximal concentration (Cmax) was unaffected. [44979] [47165] [51080] [59321] [60263] Indacaterol; Glycopyrrolate: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] (Moderate) Although no dosage adjustment of the 75 mcg indacaterol daily dose is needed, use caution if indacaterol and ritonavir are used concurrently. Monitor the patient clinically for beta-agonist side effects like tremor, nervousness, or fast, irregular heart rate. In addition, both ritonavir and long-acting beta agonists (LABAs) are associated with QT prolongation; concomitant use may increase the risk of QT prolongation. By inhibiting CYP3A4, CYP2D6, and P-glycoprotein, ritonavir reduces indacaterol metabolism. In drug interaction studies, coadministration of indacaterol 300 mcg (single dose) with ritonavir (300 mg twice daily for 7.5 days) resulted in a 1.7-fold increase in indacaterol exposure (AUC) whereas indacaterol maximal concentration (Cmax) was unaffected. [44979] [47165] [51080] [59321] [60263] Indinavir: (Moderate) Decrease the indinavir dose to 600 mg twice daily when administered in combination with lopinavir; ritonavir. The once-daily dose of lopinavir; ritonavir in combination with indinavir has not been studied. Use of these drugs together increases plasma concentrations of indinavir. [28341] [46638] (Minor) Ritonavir inhibits the clearance of indinavir, and increased indinavir serum concentrations are seen with concurrent administration. In a pharmacokinetic study in healthy volunteers, the AUC of single indinavir dose increased 185 to 475% during concurrent ritonavir dosing; the mean indinavir half-life increased from 1.2 to 2.7 hours. In an observational study of HIV-infected patients, the combination of indinavir 1200 mg and ritonavir 100 mg, both twice daily, led to high systemic exposure to indinavir and was not well tolerated. The combination of indinavir 800 mg and ritonavir 100 mg twice daily resulted in therapeutic indinavir serum concentrations with improved tolerability and similar maximum serum concentrations as the approved indinavir dosage of 800 mg three times a day. Patients should be closely monitored for possible indinavir toxicity during concurrent administration; indinavir dosage reductions may be necessary. The recommended dosing regimen for this combination is indinavir 800 mg twice daily plus ritonavir 100 or 200 mg twice daily. [26120] [26121] [46638] Inotuzumab Ozogamicin: (Major) Avoid coadministration of lopinavir with inotuzumab due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs have been associated with QT prolongation. [28341] [62245] [65157] [65170] Insulins: (Moderate) Monitor patients receiving insulin closely for changes in diabetic control, specifically hyperglycemia, when anti-retroviral protease inhibitors are instituted. New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. [30575] [60172] Interferon Alfa-2b; Ribavirin: (Major) The concomitant use of ribavirin and anti-retroviral protease inhibitors should be done with caution as both can cause hepatic damage. Most protease inhibitors have been associated with episodes of liver toxicity, with lopinavir/low-dose ritonavir, fosamprenavir/low-dose ritonavir, and nelfinavir being less hepatotoxic and tipranavir/low-dose ritonavir being the most hepatotoxic. Hyperbilirubinemia is often associated with atazanavir and/or indinavir therapy but does not reflect liver damage and is related to the inhibition of UDP glucuronosyltransferase. Overall, the HCV-HIV International Panel recommends the management of hepatotoxicity should be based on the knowledge of the mechanisms involved for each drug. Furthermore, they state that there are lower rates of liver-related mortality in coinfected patients taking HAART, even in those with end-stage liver disease, compared with patients not receiving HAART. Closely monitor patients for treatment-associated toxicities, especially hepatic decompensation. [34878] Interferons: (Moderate) The concomitant use of interferons and anti-retroviral protease inhibitors should be done with caution as both can cause hepatotoxicity. Closely monitor patients for treatment-associated toxicities, especially hepatic decompensation. Most protease inhibitors have been associated with episodes of liver toxicity. Cirrhotic chronic HCV infected patients co-infected with HIV receiving HAART and alpha interferons appear to be at increased risk for hepatic decompensation (e.g., Childs-Pugh score 6 or more) compared to patients not receiving HAART. The HCV-HIV International Panel recommends the management of hepatotoxicity should be based on the knowledge of the mechanisms involved for each drug. Furthermore, they state that there are lower rates of liver-related mortality in coinfected patients taking HAART, even in those with end-stage liver disease, compared with patients not receiving HAART. [31649] [34878] Irinotecan Liposomal: (Major) Avoid administration of ritonavir during treatment with irinotecan and for at least 1 week prior to starting therapy unless there are no therapeutic alternatives. Irinotecan is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Concomitant use may increase systemic exposure of irinotecan. [30469] [47165] Irinotecan: (Major) Avoid administration of ritonavir during treatment with irinotecan and for at least 1 week prior to starting therapy unless there are no therapeutic alternatives. Irinotecan is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Concomitant use may increase systemic exposure of irinotecan. [30469] [47165] Isavuconazonium: (Severe) Concomitant use of isavuconazonium with high-dose ritonavir (i.e., 400 mg every 12 hours) is contraindicated due to the risk for increased isavuconazole serum concentrations and serious adverse reactions, such as hepatic toxicity. Isavuconazole, the active moiety of isavuconazonium, is a sensitive substrate of hepatic isoenzyme CYP3A4; ritonavir is a strong inhibitor of this enzyme. According to the manufacturer, coadministration of isavuconazole with strong CYP3A4 inhibitors is contraindicated. Isavuconazole serum concentrations were increased 5-fold when coadministered with ketoconazole, another strong CYP3A4 inhibitor. Elevated ritonavir concentrations may also be seen with coadministration, as ritonavir is a substrate and isavuconazole is an inhibitor of CYP3A4 and the drug transporter P-glycoprotein (P-gp). [47165] [59042] (Moderate) Caution is advised when administering isavuconazonium concurrently with lopinavir. Coadministration may result in a loss of antiviral efficacy due to decreased lopinavir plasma concentrations. During drug interaction studies in healthy adults, coadministration resulted in a 27% decrease in lopinavir concentrations. [28341] [59042] Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Severe) Coadministration of rifampin and ritonavir results in markedly decreased ritonavir concentrations; HIV treatment failure and virologic resistance would be expected. Rifampin (300 or 600 mg daily for 10 days) decreases the AUC and Cmax of ritonavir (500 mg every 12 hours for 20 days) by 35% and 25%, respectively. Coadministration may lead to loss of virologic response if ritonavir is the sole protease inhibitor and increase the risk of hepatotoxicity. The DHHS/NIH HIV Treatment Guidelines recommend ritonavir and rifampin should not be coadministered and suggest the consideration of alternative antimycobacterial agents, such as rifabutin. However, CDC guidelines suggest no change in ritonavir or rifampin dose when the drugs are coadministered, but this appears to only be in the setting of low-dose ritonavir (i.e., 100 mg or 200 mg twice daily) used to 'boost' concentrations of other protease inhibitors. In this setting it would be less likely to produce adverse events than higher ritonavir doses; however, a net CYP3A4 induction still results when used with rifampin. [1299] [30314] [46638] (Severe) The coadministration of lopinavir and rifampin is contraindicated. Concurrent use may lead to loss of virologic response and possible resistance to lopinavir, the class of protease inhibitors, or other antiretroviral agents. [28341] [30314] [46638] Isoniazid, INH; Rifampin: (Severe) Coadministration of rifampin and ritonavir results in markedly decreased ritonavir concentrations; HIV treatment failure and virologic resistance would be expected. Rifampin (300 or 600 mg daily for 10 days) decreases the AUC and Cmax of ritonavir (500 mg every 12 hours for 20 days) by 35% and 25%, respectively. Coadministration may lead to loss of virologic response if ritonavir is the sole protease inhibitor and increase the risk of hepatotoxicity. The DHHS/NIH HIV Treatment Guidelines recommend ritonavir and rifampin should not be coadministered and suggest the consideration of alternative antimycobacterial agents, such as rifabutin. However, CDC guidelines suggest no change in ritonavir or rifampin dose when the drugs are coadministered, but this appears to only be in the setting of low-dose ritonavir (i.e., 100 mg or 200 mg twice daily) used to 'boost' concentrations of other protease inhibitors. In this setting it would be less likely to produce adverse events than higher ritonavir doses; however, a net CYP3A4 induction still results when used with rifampin. [1299] [30314] [46638] (Severe) The coadministration of lopinavir and rifampin is contraindicated. Concurrent use may lead to loss of virologic response and possible resistance to lopinavir, the class of protease inhibitors, or other antiretroviral agents. [28341] [30314] [46638] Isradipine: (Moderate) Concurrent administration of isradipine with protease inhibitors may result in elevated isradipine plasma concentrations and increased hypotensive effects. Isradipine is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. In addition, ritonavir prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [29128] [32432] [47165] Istradefylline: (Major) Do not exceed 20 mg once daily of istradefylline if administered with ritonavir as istradefylline exposure and adverse effects may increase. Ritonavir is a strong CYP3A4 inhibitor. Istradefylline exposure was increased by 2.5-fold when administered with a strong inhibitor in a drug interaction study. [47165] [64590] Itraconazole: (Major) Avoid coadministration of lopinavir with itraconazole due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs have been associated with QT prolongation. [28341] [40233] [57441] [65157] [65170] (Major) When administering itraconazole with ritonavir or ritonavir-containing drugs, do not exceed the maximum recommended itraconazole dose of 200 mg per day. Concurrent administration may result in increased exposure to both drugs. Monitor patients for itraconazole and ritonavir-associated adverse effects. Both itraconazole and ritonavir are strong CYP3A4 inhibitors and substrates. [27983] [47165] Ivabradine: (Severe) Coadministration of ivabradine and ritonavir is contraindicated. Ivabradine is primarily metabolized by CYP3A4; ritonavir is a strong CYP3A4 inhibitor. Coadministration will increase the plasma concentrations of ivabradine. Increased ivabradine concentrations may result in bradycardia exacerbation and conduction disturbances. [59430] Ivacaftor: (Major) If ritonavir and ivacaftor are taken together, administer ivacaftor at the usual recommended dose but reduce the frequency to twice weekly. Ivacaftor is a CYP3A substrate and ritonavir is a CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased ivacaftor exposure by 8.5-fold. [48524] Ivosidenib: (Major) Avoid coadministration of ivosidenib with ritonavir due to increased plasma concentrations of ivosidenib, which increases the risk of QT prolongation. If concomitant use is unavoidable, reduce the dose of ivosidenib to 250 mg PO once daily. Monitor ECGs for QTc prolongation and monitor electrolytes, correcting any electrolyte abnormalities as clinically appropriate. If ritonavir is discontinued, wait at least 5 half-lives of ritonavir before increasing the dose of ivosidenib to the recommended dose of 500 mg PO once daily. Ivosidenib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased ivosidenib single-dose AUC to 269% of control, with no change in Cmax. [47165] [63368] (Major) Avoid coadministration of lopinavir with ivosidenib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Interrupt or dose reduce ivosidenib if QT prolongation occurs. Prolongation of the QTc interval and ventricular arrhythmias have been reported in patients treated with ivosidenib. Lopinavir is associated with QT prolongation. [28341] [63368] [65157] [65170] Ixabepilone: (Major) If possible, avoid coadministration of ixabepilone with ritonavir; concurrent use is expected to result in increased ixabepilone plasma concentrations and risk of adverse events. Consider alternative therapies before using ixabepilone with ritonavir. If coadministration of ixabepilone with ritonavir cannot be avoided, consider an ixabepilone dosage reduction to 20 mg/m2 IV over 3 hours given every 3 weeks, as this dose is predicted to adjust the ixabepilone AUC to the range observed without inhibitors. Carefully monitor for adverse events. If a patient is already receiving ritonavir, a washout period of approximately 1 week is recommended before starting ixabepilone. Ixabepilone is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is a potent inhibitor of this enzyme. [10415] [47165] Ketamine: (Moderate) Use caution if ritonavir is coadministered with ketamine due to the potential for increased ketamine exposure which may increase the risk of toxicity. Ketamine is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. [37294] [47165] [65210] Ketoconazole: (Major) Avoid coadministration of lopinavir with ketoconazole due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs have been associated with QT prolongation. [27982] [28341] [65157] [65170] (Major) When administering ketoconazole with ritonavir or ritonavir-containing drugs, do not exceed the maximum recommended ketoconazole dose of 200 mg per day. Concurrent administration of ritonavir (a potent CYP3A4 inhibitor) with ketoconazole (a CYP3A4 substrate) significantly increases ketoconazole systemic concentrations. In one drug interaction study, ketoconazole exposure was increased by 3.4-fold when given concurrently with ritonavir (500 mg twice daily). [27982] [47165] Labetalol: (Moderate) Cardiac and neurologic events have been reported when ritonavir was concurrently administered with beta-blockers. [5044] Lacosamide: (Moderate) Lacosamide causes PR interval prolongation in some patients. Caution is advised during coadministration of lacosamide with other drugs that cause PR prolongation, such as lopinavir, since further PR prolongation is possible. [28341] [34626] (Moderate) Use caution during concurrent use of lacosamide and ritonavir, particularly in patients with renal or hepatic impairment. Lacosamide is a CYP3A4 substrate; ritonavir is a potent inhibitor of CYP3A4. Patients with renal or hepatic impairment may have significantly increased exposure to lacosamide if coadministered with a strong CYP3A4 inhibitor. Dosage reduction of lacosamide may be necessary in this population. [28315] [34626] Lamivudine, 3TC; Zidovudine, ZDV: (Minor) Since ritonavir induces glucuronidation, there is the potential for reduction in zidovudine, ZDV plasma concentrations during concurrent therapy with ritonavir. When coadministered with ritonavir, the AUC and Cmax of zidovudine, ZDV are decreased by 12% and 27%. The clinical significance of this interaction is unknown. [28315] [47165] [58664] Lamivudine; Tenofovir Disoproxil Fumarate: (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrate, concurrently with inhibitors of P-gp and BCRP, such as ritonavir. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. [28193] [58664] (Minor) There are varying results in reports of an interaction between tenofovir and lopinavir; ritonavir. In one report, the concurrent administration of tenofovir with lopinavir; ritonavir increased tenofovir Cmax 31%, AUC 34%, and Cmin 29%, with slight (15%) decreases in lopinavir Cmax and AUC; the alterations may be a food effect rather than a drug-drug interaction. In another report, lopinavir; ritonavir (400 mg; 100 mg PO twice daily for 14 days) increased the tenofovir (300 mg/day PO) Cmin 51% and AUC 32%, with no effect seen on lopinavir; ritonavir pharmacokinetics. While the clinical significance of this interaction is unknown, and is suspected to be insignificant, patients receiving lopinavir; ritonavir with tenofovir should be monitored for tenofovir-associated adverse events. [46638] Lamotrigine: (Major) Adjustments in lamotrigine escalation and maintenance dose regimens are necessary with concomitant lopinavir; ritonavir use. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and lopinavir; ritonavir induces glucuronidation. During concurrent use of lamotrigine with lopinavir; ritonavir in 18 healthy subjects, induction of glucuronidation by lopinavir (400 mg twice daily); ritonavir (100 mg twice daily) decreased lamotrigine AUC, Cmax, and half-life by approximately 50% to 55.4%. [28451] Lansoprazole: (Moderate) Increased exposure to lansoprazole may occur during concurrent administration of ritonavir. Although dosage adjustment of lansoprazole is not normally required, dosage reduction may be considered in patients receiving higher lansoprazole doses (e.g., those with Zollinger-Ellison syndrome). Ritonavir is a strong CYP3A4 inhibitor. Lansoprazole is a CYP2C19 and CYP3A4 substrate. Coadministration of a dual CYP2C19/strong CYP3A4 inhibitor increased the lansoprazole AUC by an average of 4-times. [40596] [47165] Lansoprazole; Naproxen: (Moderate) Increased exposure to lansoprazole may occur during concurrent administration of ritonavir. Although dosage adjustment of lansoprazole is not normally required, dosage reduction may be considered in patients receiving higher lansoprazole doses (e.g., those with Zollinger-Ellison syndrome). Ritonavir is a strong CYP3A4 inhibitor. Lansoprazole is a CYP2C19 and CYP3A4 substrate. Coadministration of a dual CYP2C19/strong CYP3A4 inhibitor increased the lansoprazole AUC by an average of 4-times. [40596] [47165] Lanthanum Carbonate: (Major) Oral compounds known to interact with antacids, like protease inhibitors, should not be taken within 2 hours of dosing with lanthanum carbonate. If these agents are used concomitantly, space the dosing intervals appropriately. Monitor serum concentrations and clinical condition. [9126] Lapatinib: (Major) Avoid coadministration of lapatinib with ritonavir due to increased plasma concentrations of lapatinib. If concomitant use is unavoidable, decrease the dose of lapatinib to 500 mg PO once daily. If ritonavir is discontinued, increase lapatinib to the indicated dose after a washout period of approximately 1 week. Lapatinib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Concomitant use with another strong CYP3A4 inhibitor increased lapatinib exposure by 3.6-fold and increased the half-life of lapatinib by 1.7-fold. [33192] [47165] (Major) Avoid coadministration of lopinavir with lapatinib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Lapatinib has been associated with concentration-dependent QT prolongation; ventricular arrhythmias and torsade de pointes (TdP) have been reported in postmarketing experience. [28341] [33192] [65157] [65170] Larotrectinib: (Major) Avoid coadministration of larotrectinib with ritonavir due to increased larotrectinib exposure resulting in increased treatment-related adverse effects. If coadministration cannot be avoided, reduce the larotrectinib dose by 50%. If ritonavir is discontinued, resume the original larotrectinib dose after 3 to 5 elimination half-lives of ritonavir. Larotrectinib is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor increased the AUC of larotrectinib by 4.3-fold in a drug interaction study. [47165] [63780] Ledipasvir; Sofosbuvir: (Moderate) Caution is warranted when ritonavir is administered with ledipasvir; sofosbuvir as there is a potential for elevated concentrations of ledipasvir and sofosbuvir. Ritonavir is an inhibitor of the transporter P-glycoprotein (P-gp). Both ledipasvir and sofosbuvir are substrates of P-gp. According to the manufacturer, no dosage adjustments are required when ledipasvir; sofosbuvir is administered concurrently with P-gp inhibitors; however, if these drugs are given together, consider increased monitoring for potential adverse effects. [28380] [47165] [58167] Lefamulin: (Major) Avoid coadministration of lopinavir with lefamulin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Lefamulin has a concentration dependent QTc prolongation effect. The pharmacodynamic interaction potential to prolong the QT interval of the electrocardiogram between lefamulin and other drugs that effect cardiac conduction is unknown. [28341] [64576] [65157] [65170] (Major) Avoid coadministration of ritonavir with oral lefamulin due to increased lefamulin exposure; ritonavir may be administered with intravenous lefamulin. Lefamulin is a CYP3A4 and P-gp substrate and ritonavir is a P-gp and strong CYP3A4 inhibitor. Coadministration of a combined P-gp and strong CYP3A4 inhibitor increased the exposure of oral and intravenous lefamulin by 165% and 31%, respectively. [47165] [64576] Lemborexant: (Major) Avoid coadministration of lemborexant and ritonavir as concurrent use is expected to significantly increase lemborexant exposure and the risk of adverse CNS effects. Lemborexant is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Coadministration of lemborexant with another strong CYP3A4 inhibitor increased the lemborexant AUC by up to 4.5-fold. [47165] [64870] Lenvatinib: (Major) Avoid coadministration of lopinavir with lenvatinib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Prolongation of the QT interval has also been reported with lenvatinib therapy. [28341] [58782] [65157] [65170] Lesinurad: (Moderate) Ritonavir may decrease the systemic exposure and therapeutic effect of lesinurad; monitor for potential reduction in efficacy. Ritonavir is a CYP2C9 inducer, and lesinurad is a CYP2C9 substrate. [26120] [28315] [60473] Lesinurad; Allopurinol: (Moderate) Ritonavir may decrease the systemic exposure and therapeutic effect of lesinurad; monitor for potential reduction in efficacy. Ritonavir is a CYP2C9 inducer, and lesinurad is a CYP2C9 substrate. [26120] [28315] [60473] Letermovir: (Moderate) A clinically relevant increase in the plasma concentration of ritonavir may occur if given with letermovir. In patients who are also receiving treatment with cyclosporine, the magnitude of this interaction may be amplified. Ritonavir is primarily metabolized by CYP3A. Letermovir is a moderate CYP3A4 inhibitor; however, when given with cyclosporine, the combined effect on CYP3A4 substrates may be similar to a strong CYP3A4 inhibitor. [47165] [62611] (Moderate) Administering lopinavir concurrently with letermovir may result in elevated concentrations of both drugs. The exposure to lopinavir may be further increased if the patient is receiving letermovir combined with cyclosporine. Closely monitor for adverse events, including fast or irregular heartbeats, severe rash, hepatotoxicity, and gastrointestinal events. Lopinavir is an inhibitor of the organic anion-transporting polypeptide (OATP1B1), and a substrate of CYP3A4. Letermovir is an OATP1B1 substrate and a moderate CYP3A4 inhibitor. When given with cyclosporine, the combined effect of letermovir and cyclosporine on CYP3A4 substrates may be similar to a strong CYP3A4 inhibitor. [28341] [56579] [61510] [61511] [61513] [62611] Leuprolide: (Major) Avoid coadministration of lopinavir with leuprolide due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Androgen deprivation therapy (i.e., leuprolide) may prolong the QT/QTc interval. [28341] [43800] [65157] [65170] Leuprolide; Norethindrone: (Major) Avoid coadministration of lopinavir with leuprolide due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Androgen deprivation therapy (i.e., leuprolide) may prolong the QT/QTc interval. [28341] [43800] [65157] [65170] (Moderate) Many anti-retroviral protease inhibitors may interact with hormonal agents like norethindrone, due to their actions on CYP metabolism, particularly CYP3A4. Data on the effects that protease inhibitors have on the serum concentrations of norethindrone are complex and are based mostly off of data with norethindrone-containing contraceptives. For example, ritonavir (also found in combinations like lopinavir; ritonavir, and used as a booster in many HIV treatment regimens) may decrease the metabolism of norethindrone, raising norethindrone concentrations. Women receiving norethindrone for hormone replacement or contraception should report potential hormonal adverse effects (e.g., bleeding pattern changes, acne, emotional lability) or any changes in efficacy (e.g., noted changes in bleeding patterns) to their prescribers. Because norethindrone-containing contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive norethindrone contraception concurrently with ritonavir should use an additional barrier method of contraception such as condoms. [58679] [7731] Levalbuterol: (Major) Avoid coadministration of lopinavir with short-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28341] [33925] [65157] [65170] Levamlodipine: (Moderate) Amlodipine is a CYP3A4 substrate. Theoretically, CYP3A4 inhibitors, such as anti-retroviral protease inhibitors, may increase the plasma concentration of amlodipine via CYP3A4 inhibition; this effect might lead to hypotension in some individuals. Caution should be used when anti-retroviral protease inhibitors are coadministered with amlodipine; therapeutic response should be monitored. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [29090] [47165] [58664] Levobupivacaine: (Minor) Levobupivacaine is metabolized by CYP3A4 and CYP1A2. Known inhibitors of CYP3A4, such as ritonavir, may result in increased systemic levels of levobupivacaine when given concurrently, with potential for toxicity. Although not studied, dosage adjustments of levobupivacaine may be needed. [5637] Levocetirizine: (Moderate) Coadministration of cetirizine and ritonavir resulted in a 42% increase in the AUC, 53% increase in half-life, and 29% decrease in clearance of cetirizine. Cetirizine did not alter ritonavir disposition. [28874] [33350] Levofloxacin: (Major) Avoid coadministration of lopinavir with levofloxacin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Levofloxacin has been associated with a risk of QT prolongation and torsade de pointes (TdP). Although extremely rare, torsade de pointes has been reported during postmarketing surveillance of levofloxacin. [28341] [28421] [65157] [65170] Levomethadyl: (Major) Agents that inhibit hepatic cytochrome P450 CYP 3A4, including ritonavir, may decrease the metabolism of levomethadyl, increase levomethadyl levels, and may precipitate severe arrhythmias including torsade de pointes. [4718] Levomilnacipran: (Major) The adult dose of levomilnacipran should not exceed 80 mg/day during concurrent use of strong CYP3A4 inhibitors such as ritonavir. Levomilnacipran is partially metabolized by CYP3A4, and decreased metabolism of the drug can lead to an increased risk of adverse effects such as urinary retention. Additionally, ritonavir could further increase levomilnacipran concentrations by inhibiting its P-glycoprotein (P-gp) metabolism. [55469] Levonorgestrel: (Major) Data on the effects that protease inhibitors have on the serum concentrations of estrogens and progestins are complex. Some protease inhibitors increase (i.e., ritonavir, lopinavir; ritonavir, nelfinavir, tipranavir) and others decrease (i.e., atazanavir, indinavir) the metabolism of hormonal contraceptives. The safety and efficacy of hormonal contraceptives may be affected if coadministered with protease inhibitors. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors concurrently should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with protease inhibitors to use an additional method of contraception to protect against unwanted pregnancy, unless other drug-specific recommendations are made by the manufacturer of the protease inhibitor. Furthermore, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with protease inhibitors should use an additional barrier method of contraception such as condoms. [46638] [5044] Levorphanol: (Moderate) Ritonavir is an inhibitor of the cytochrome P450 3A4 isoenzyme and may decrease the metabolism of levorphanol if the two drugs are coadministered. [4718] Lidocaine: (Moderate) Anti-retroviral protease inhibitors can inhibit hepatic cytochrome P450 3A4, an isoenzyme that is partially responsible for the metabolism of lidocaine. The concurrent use of systemic lidocaine and anti-retroviral protease inhibitors should be carefully monitored due to the potential for serious toxicity. [4718] [5172] Lidocaine; Prilocaine: (Moderate) Anti-retroviral protease inhibitors can inhibit hepatic cytochrome P450 3A4, an isoenzyme that is partially responsible for the metabolism of lidocaine. The concurrent use of systemic lidocaine and anti-retroviral protease inhibitors should be carefully monitored due to the potential for serious toxicity. [4718] [5172] Linagliptin: (Moderate) Monitor for changes in glycemic control, specifically hyperglycemia, if ritonavir is administered concurrently with linagliptin. New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. [28315] [30575] [31240] [34557] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy, such as linagliptin, should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [28341] [30575] Linagliptin; Metformin: (Moderate) Monitor for changes in glycemic control, specifically hyperglycemia, if ritonavir is administered concurrently with linagliptin. New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. [28315] [30575] [31240] [34557] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy, such as linagliptin, should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [28341] [30575] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30480] [30575] Lisdexamfetamine: (Moderate) Warn patients that the risk of amphetamine toxicity may be increased during concurrent use of ritonavir, a strong CYP2D6 inhibitor. Amphetamines are partially metabolized by CYP2D6 and have serotonergic properties; inhibition of amphetamine metabolism may increase the risk of serotonin syndrome or other toxicity. If serotonin syndrome occurs, both the amphetamine and CYP2D6 inhibitor should be discontinued and appropriate medical treatment should be implemented. [25887] [29219] [33263] [47165] [57067] Lithium: (Major) Avoid coadministration of lopinavir with lithium due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs are associated with QT prolongation. [28341] [59809] [59810] [59811] [65157] [65170] Lofexidine: (Major) Avoid coadministration of lopinavir with lofexidine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs have been associated with QT prolongation. [28341] [63161] [65157] [65170] Lomitapide: (Severe) Concomitant use of ritonavir and lomitapide is contraindicated. If treatment with ritonavir is unavoidable, lomitapide should be stopped during the course of treatment. Ritonavir is a strong CYP3A4 inhibitor. The exposure to lomitapide was increased 27-fold in the presence of ketoconazole, a strong CYP3A4 inhibitor. [52698] Long-acting beta-agonists: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] Loperamide: (Major) Avoid coadministration of lopinavir with loperamide due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. At high doses, loperamide has been associated with serious cardiac toxicities, including syncope, ventricular tachycardia, QT prolongation, torsade de pointes (TdP), and cardiac arrest. [28341] [30106] [60864] [65157] [65170] (Moderate) Concurrent administration of loperamide and ritonavir may increase the risk for adverse reactions, such as CNS events and cardiac toxicities (i.e., syncope, ventricular tachycardia, QT prolongation, torsade de pointes, cardiac arrest). At high doses, loperamide has been associated with serious cardiac toxicities, including syncope, ventricular tachycardia, QT prolongation, TdP, and cardiac arrest. Loperamide is a substrate for the enzymes CYP3A4, CYP2D6, and the drug transporter P-glycoprotein (P-gp); ritonavir is an inhibitor of both enzymes and P-gp. When these drugs were administered together, an increase was seen in loperamide's Cmax (17%), Tmax (56%), AUC (223%), and amount excreted in the urine (118%). There was also a decrease in loperamide's oral clearance (70%). No CNS opioid effects (e.g., changes in pupil diameter, changes in pO2 or pCO2) were observed in this study, but it should be noted that because ritonavir is a potent P-gp inhibitor, it has the potential to hinder transport of loperamide out of the CNS and thereby depress respiratory ventilation. Monitor for depressed respiratory ventilation and adverse cardiac effects if these drugs are to be coadministered. [30106] [47165] [60864] Loperamide; Simethicone: (Major) Avoid coadministration of lopinavir with loperamide due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. At high doses, loperamide has been associated with serious cardiac toxicities, including syncope, ventricular tachycardia, QT prolongation, torsade de pointes (TdP), and cardiac arrest. [28341] [30106] [60864] [65157] [65170] (Moderate) Concurrent administration of loperamide and ritonavir may increase the risk for adverse reactions, such as CNS events and cardiac toxicities (i.e., syncope, ventricular tachycardia, QT prolongation, torsade de pointes, cardiac arrest). At high doses, loperamide has been associated with serious cardiac toxicities, including syncope, ventricular tachycardia, QT prolongation, TdP, and cardiac arrest. Loperamide is a substrate for the enzymes CYP3A4, CYP2D6, and the drug transporter P-glycoprotein (P-gp); ritonavir is an inhibitor of both enzymes and P-gp. When these drugs were administered together, an increase was seen in loperamide's Cmax (17%), Tmax (56%), AUC (223%), and amount excreted in the urine (118%). There was also a decrease in loperamide's oral clearance (70%). No CNS opioid effects (e.g., changes in pupil diameter, changes in pO2 or pCO2) were observed in this study, but it should be noted that because ritonavir is a potent P-gp inhibitor, it has the potential to hinder transport of loperamide out of the CNS and thereby depress respiratory ventilation. Monitor for depressed respiratory ventilation and adverse cardiac effects if these drugs are to be coadministered. [30106] [47165] [60864] Lorlatinib: (Major) Avoid coadministration of lorlatinib with ritonavir due to increased plasma concentrations of lorlatinib, which may increase the incidence and severity of adverse reactions. Ritonavir plasma concentrations may also decrease, leading to reduced efficacy and increasing the potential for viral resistance. If concomitant use is unavoidable, reduce the starting dose of lorlatinib from 100 mg to 75 mg once daily, or from 75 mg to 50 mg once daily. If ritonavir is discontinued, resume the original dose of lorlatinib after 3 half-lives of ritonavir. Lorlatinib is a CYP3A substrate and moderate inducer. Ritonavir is a CYP3A4 substrate and strong inhibitor. Coadministration with another strong CYP3A4 inhibitor increased lorlatinib exposure by 42%. [47165] [63732] (Moderate) Concurrent administration of lorlatinib with lopinavir may result in decreased lopinavir plasma concentrations; thereby, reducing efficacy and increasing the potential for viral resistance. Lorlatinib is a moderate CYP3A4 inducer. Lopinavir is a CYP3A4 substrate. [28341] [56579] [63732] Losartan: (Moderate) Concurrent administration of losartan with ritonavir may result in elevated losartan plasma concentrations. Losartan is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [47165] [5339] [58664] Lovastatin: (Severe) Concurrent use of lovastatin and anti-retroviral protease inhibitors is contraindicated. The risk of developing myopathy, rhabdomyolysis, and acute renal failure is substantially increased if lovastatin is administered concomitantly with anti-retroviral protease inhibitors. Lovastatin is a substrate of CYP3A4 and anti-retroviral protease inhibitors are strong inhibitors of CYP3A4; therefore, coadministration may result in substantial increases in plasma concentrations of lovastatin. [28604] Lovastatin; Niacin: (Severe) Concurrent use of lovastatin and anti-retroviral protease inhibitors is contraindicated. The risk of developing myopathy, rhabdomyolysis, and acute renal failure is substantially increased if lovastatin is administered concomitantly with anti-retroviral protease inhibitors. Lovastatin is a substrate of CYP3A4 and anti-retroviral protease inhibitors are strong inhibitors of CYP3A4; therefore, coadministration may result in substantial increases in plasma concentrations of lovastatin. [28604] Lumacaftor; Ivacaftor: (Major) If ritonavir and ivacaftor are taken together, administer ivacaftor at the usual recommended dose but reduce the frequency to twice weekly. Ivacaftor is a CYP3A substrate and ritonavir is a CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased ivacaftor exposure by 8.5-fold. [48524] (Major) Lumacaftor; ivacaftor may decrease the therapeutic efficacy of lopinavir; avoid concurrent use if possible. If concomitant use of lopinavir is necessary, monitor antiretroviral efficacy and adjust therapy as necessary. Lumacaftor; ivacaftor dosage adjustment is not required when lopinavir is started in a patient already taking lumacaftor; ivacaftor. However, if lumacaftor; ivacaftor is initiated in a patient already taking lopinavir, reduce the dose of lumacaftor; ivacaftor to 1 tablet PO daily or 1 packet of oral granules every other day for the first week of treatment, and then increase to the usual recommended daily dose. This dosage adjustment is also necessary if lumacaftor; ivacaftor therapy has been interrupted for more than 1 week and re-initiated while the patient is taking lopinavir. The 1-week lead-in period at the lower lumacaftor; ivacaftor dosage allows for lumacaftor's induction of CYP3A to reach steady state. Lopinavir is a substrate of CYP3A. Lumacaftor is a strong CYP3A inducer. Lumacaftor's induction of CYP3A may decrease the systemic exposure of lopinavir and decrease its therapeutic efficacy. [28341] [56579] [59891] (Major) Lumacaftor; ivacaftor may decrease the therapeutic efficacy of ritonavir; avoid concurrent use if possible. If concomitant use of ritonavir is necessary, monitor antiretroviral efficacy and adjust therapy as necessary. Lumacaftor; ivacaftor dosage adjustment is not required when ritonavir is started in a patient already taking lumacaftor; ivacaftor. However, if lumacaftor; ivacaftor is initiated in a patient already taking ritonavir, reduce the dose of lumacaftor; ivacaftor to 1 tablet PO daily or 1 packet of oral granules every other day for the first week of treatment, and then increase to the usual recommended daily dose. This dosage adjustment is also necessary if lumacaftor; ivacaftor therapy has been interrupted for more than 1 week and re-initiated while the patient is taking ritonavir. The 1-week lead-in period at the lower lumacaftor; ivacaftor dosage allows for lumacaftor's induction of CYP3A to reach steady state. Ritonavir is a substrate and strong inhibitor of CYP3A. Ivacaftor is a CYP3A substrate, and lumacaftor is a strong CYP3A inducer. Lumacaftor's induction of CYP3A may decrease the systemic exposure of ritonavir and decrease its therapeutic efficacy. Although ritonavir is a strong CYP3A4 inhibitor, net ivacaftor exposure at steady state is not expected to exceed that achieved with ivacaftor monotherapy (i.e., 150 mg PO every 12 hours) because of lumacaftor's CYP3A induction. In pharmacokinetic studies, coadministration of lumacaftor; ivacaftor with another strong CYP3A4 inhibitor increased ivacaftor exposure by 4.3-fold. Lastly, ritonavir is also a substrate of the drug transporter P-glycoprotein (P-gp), and lumacaftor; ivacaftor has the potential to both induce and inhibit P-gp. The net effect on P-gp substrates is not clear, but their exposure may be affected. [28142] [59891] Lumacaftor; Ivacaftor: (Major) Lumacaftor; ivacaftor may decrease the therapeutic efficacy of lopinavir; avoid concurrent use if possible. If concomitant use of lopinavir is necessary, monitor antiretroviral efficacy and adjust therapy as necessary. Lumacaftor; ivacaftor dosage adjustment is not required when lopinavir is started in a patient already taking lumacaftor; ivacaftor. However, if lumacaftor; ivacaftor is initiated in a patient already taking lopinavir, reduce the dose of lumacaftor; ivacaftor to 1 tablet PO daily or 1 packet of oral granules every other day for the first week of treatment, and then increase to the usual recommended daily dose. This dosage adjustment is also necessary if lumacaftor; ivacaftor therapy has been interrupted for more than 1 week and re-initiated while the patient is taking lopinavir. The 1-week lead-in period at the lower lumacaftor; ivacaftor dosage allows for lumacaftor's induction of CYP3A to reach steady state. Lopinavir is a substrate of CYP3A. Lumacaftor is a strong CYP3A inducer. Lumacaftor's induction of CYP3A may decrease the systemic exposure of lopinavir and decrease its therapeutic efficacy. [28341] [56579] [59891] (Major) Lumacaftor; ivacaftor may decrease the therapeutic efficacy of ritonavir; avoid concurrent use if possible. If concomitant use of ritonavir is necessary, monitor antiretroviral efficacy and adjust therapy as necessary. Lumacaftor; ivacaftor dosage adjustment is not required when ritonavir is started in a patient already taking lumacaftor; ivacaftor. However, if lumacaftor; ivacaftor is initiated in a patient already taking ritonavir, reduce the dose of lumacaftor; ivacaftor to 1 tablet PO daily or 1 packet of oral granules every other day for the first week of treatment, and then increase to the usual recommended daily dose. This dosage adjustment is also necessary if lumacaftor; ivacaftor therapy has been interrupted for more than 1 week and re-initiated while the patient is taking ritonavir. The 1-week lead-in period at the lower lumacaftor; ivacaftor dosage allows for lumacaftor's induction of CYP3A to reach steady state. Ritonavir is a substrate and strong inhibitor of CYP3A. Ivacaftor is a CYP3A substrate, and lumacaftor is a strong CYP3A inducer. Lumacaftor's induction of CYP3A may decrease the systemic exposure of ritonavir and decrease its therapeutic efficacy. Although ritonavir is a strong CYP3A4 inhibitor, net ivacaftor exposure at steady state is not expected to exceed that achieved with ivacaftor monotherapy (i.e., 150 mg PO every 12 hours) because of lumacaftor's CYP3A induction. In pharmacokinetic studies, coadministration of lumacaftor; ivacaftor with another strong CYP3A4 inhibitor increased ivacaftor exposure by 4.3-fold. Lastly, ritonavir is also a substrate of the drug transporter P-glycoprotein (P-gp), and lumacaftor; ivacaftor has the potential to both induce and inhibit P-gp. The net effect on P-gp substrates is not clear, but their exposure may be affected. [28142] [59891] Lumateperone: (Major) Avoid coadministration of lumateperone and ritonavir as concurrent use may increase lumateperone exposure and the risk of adverse effects. Lumateperone is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased lumateperone exposure by approximately 4-fold. [47165] [64885] Lurasidone: (Severe) Concurrent use of lurasidone with strong CYP3A4 inhibitors, such as ritonavir, is contraindicated. Lurasidone is primarily metabolized by CYP3A4. Increased lurasidone plasma concentrations are expected when the drug is co-administered with inhibitors of CYP3A4. [28315] [42227] [47165] Lurbinectedin: (Major) Avoid coadministration of lurbinectedin and ritonavir due to the risk of increased lurbinectedin exposure which may increase the incidence of lurbinectedin-related adverse reactions. Lurbinectedin is a CYP3A substrate and ritonavir is a strong CYP3A inhibitor. [47165] [65593] Macimorelin: (Major) Avoid coadministration of lopinavir with macimorelin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Sufficient washout time of drugs that are known to prolong the QT interval prior to administration of macimorelin is recommended. Treatment with macimorelin has been associated with an increase in the corrected QT (QTc) interval. Lopinavir is associated with QT prolongation. [28341] [62723] [65157] [65170] Macitentan: (Major) Avoid concurrent use of macitentan and ritonavir. Ritonavir is a strong inhibitor of CYP3A4. Coadministration of macitentan with another strong CYP3A4 inhibitor approximately doubled macitentan exposure. Consider alternative treatment options for pulmonary hypertension if treatment with ritonavir is necessary. [56260] Maprotiline: (Major) Avoid coadministration of lopinavir with maprotiline due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Maprotiline has been reported to prolong the QT interval, particularly in overdose or with higher-dose prescription therapy (elevated serum concentrations). Cases of long QT syndrome and torsade de pointes (TdP) tachycardia have been described with maprotiline use, but rarely occur when the drug is used alone in normal prescribed doses and in the absence of other known risk factors for QT prolongation. Limited data are available regarding the safety of maprotiline in combination with other QT-prolonging drugs. [28341] [28415] [4951] [5491] [65157] [65170] (Moderate) Ritonavir potently inhibits the CYP2D6 and CYP3A4 isozymes, and thus may inhibit the metabolism of maprotiline. Since the magnitude of the interaction with the maprotiline is difficult to predict but may be significant, monitor patients receiving ritonavir and maprotiline concurrently closely. Adjust the dosage of maprotiline based on therapeutic response. Maprotiline serum concentration monitoring may be useful to guide adjustments and prevent toxicity. [28759] [46638] [47165] [5542] Maraviroc: (Major) Coadministration of maraviroc (a substrate of CYP3A, P-gp, MRP2) with ritonavir (a strong CYP3A4 inhibitor and P-gp/MRP2 inhibitor) has been reported to significantly increase maraviroc concentrations. Reduce the dose of maraviroc when coadministered with strong CYP3A inhibitors; coadministration of maraviroc with strong CYP3A inhibitors is contraindicated in patients with CrCl less than 30 mL/min. Adjust the maraviroc dosage as follows when administered with ritonavir (with or without a concomitant CYP3A inducer): adults and children weighing 40 kg or more: 150 mg PO twice daily; children weighing 30 to 39 kg: 100 mg PO twice daily; children weighing 20 to 29 kg: 75 mg PO twice daily (or 80 mg PO twice daily for solution); children weighing 10 to 19 kg: 50 mg PO twice daily. [28380] [33473] [46638] [60845] (Major) Coadministration of maraviroc, a substrate of organic anion-transporting polypeptide (OATP1B1), with lopinavir, a OATP1B1 inhibitor, has been reported to increase maraviroc exposure. Adjust the maraviroc dosage as follows when administered with lopinavir; ritonavir (with or without a concomitant CYP3A inducer): adults and children weighing 40 kg or more: 150 mg PO twice daily; children weighing 30 to 39 kg: 100 mg PO twice daily; children weighing 20 to 29 kg: 75 mg PO twice daily (or 80 mg PO twice daily for solution); children weighing 10 to 19 kg: 50 mg PO twice daily. [28341] [28380] [33473] [46638] [56579] [61510] Meclizine: (Moderate) Concurrent administration of meclizine with ritonavir may result in elevated meclizine plasma concentrations. Meclizine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [43856] [47165] [58664] Medroxyprogesterone: (Major) Coadministration of medroxyprogesterone, a CYP3A substrate with ritonavir, a strong CYP3A inhibitor should be avoided since it is expected to increase concentrations of medroxyprogesterone acetate. Formal drug interaction studies have not been conducted; however, medroxyprogesterone is metabolized primarily by hydroxylation via the CYP3A4 in vitro. [28380] [34557] [47165] [57648] Mefloquine: (Major) Avoid coadministration of lopinavir with mefloquine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. There is evidence that the use of halofantrine after mefloquine causes a significant lengthening of the QTc interval. Mefloquine alone has not been reported to cause QT prolongation. [28301] [28341] [65157] [65170] (Moderate) The plasma concentrations of mefloquine may be elevated when administered concurrently with ritonavir. Clinical monitoring for adverse effects, such as GI or neuropsychiatric effects, is recommended during coadministration. Ritonavir is a strong inhibitor of CYP3A4 and P-glycoprotein (P-gp) inhibitor, while mefloquine is a CYP3A4 and P-gp substrate. [28301] [47165] Meloxicam: (Moderate) Concurrent administration of meloxicam with ritonavir may result in elevated meloxicam plasma concentrations. Meloxicam is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [47165] [58664] [6352] Meperidine: (Severe) Concomitant use of high-dose, long-term meperidine therapy with ritonavir is not recommended due the increased concentration of the neurotoxic metabolite of meperidine, normeperidine. Ritonavir is associated with a 62% decrease in meperidine AUC thought to be due to increased meperidine metabolism. The AUC and Cmax of normeperidine, the toxic metabolite of meperidine, increased 47% and 87%, respectively, with concurrent administration of ritonavir. [28315] [46638] [47165] [58664] Meperidine; Promethazine: (Severe) Concomitant use of high-dose, long-term meperidine therapy with ritonavir is not recommended due the increased concentration of the neurotoxic metabolite of meperidine, normeperidine. Ritonavir is associated with a 62% decrease in meperidine AUC thought to be due to increased meperidine metabolism. The AUC and Cmax of normeperidine, the toxic metabolite of meperidine, increased 47% and 87%, respectively, with concurrent administration of ritonavir. [28315] [46638] [47165] [58664] (Major) Avoid coadministration of lopinavir with promethazine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Promethazine, a phenothiazine, is also associated with a possible risk for QT prolongation. [28225] [28341] [55578] [65157] [65170] Mephobarbital: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] Mesoridazine: (Major) QT prolongation in patients taking lopinavir; ritonavir has been reported. Coadministration of lopinavir; ritonavir with other drugs that prolong the QT interval, such as mesoridazine, may result in additive QT prolongation. [28341] [4951] [5831] Mestranol; Norethindrone: (Major) Ritonavir increases the metabolism of mestranol. Women receiving hormonal contraceptives and ritonavir should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with ritonavir to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with ritonavir should use an additional barrier method of contraception such as condoms. [5044] [7731] (Moderate) Many anti-retroviral protease inhibitors may interact with hormonal agents like norethindrone, due to their actions on CYP metabolism, particularly CYP3A4. Data on the effects that protease inhibitors have on the serum concentrations of norethindrone are complex and are based mostly off of data with norethindrone-containing contraceptives. For example, ritonavir (also found in combinations like lopinavir; ritonavir, and used as a booster in many HIV treatment regimens) may decrease the metabolism of norethindrone, raising norethindrone concentrations. Women receiving norethindrone for hormone replacement or contraception should report potential hormonal adverse effects (e.g., bleeding pattern changes, acne, emotional lability) or any changes in efficacy (e.g., noted changes in bleeding patterns) to their prescribers. Because norethindrone-containing contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive norethindrone contraception concurrently with ritonavir should use an additional barrier method of contraception such as condoms. [58679] [7731] Metaproterenol: (Major) Avoid coadministration of lopinavir with short-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28341] [33925] [65157] [65170] Metformin: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30480] [30575] Metformin; Pioglitazone: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30480] [30575] Metformin; Repaglinide: (Moderate) Coadministration of repaglinide and protease inhibitors may increase or decrease glucose concentrations and increase repaglinide AUC; if coadministration is necessary, repaglinide dosage adjustment may be necessary and increased frequency of glucose monitoring is recommended. New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. In addition, repaglinide is a substrate of the hepatic isoenzyme CYP3A4 and the drug transporter organic anion transporting polypeptide (OATP1B1); protease inhibitors are potent CYP3A4 inhibitors and inhibitors of OATP. [29751] [31281] [36049] [61511] [61513] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30480] [30575] Metformin; Rosiglitazone: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30480] [30575] Metformin; Saxagliptin: (Major) The metabolism of saxagliptin is primarily mediated by CYP3A4/5. The saxagliptin dose is limited to 2.5 mg once daily when coadministered with a strong CYP3A4/5 inhibitor such as ritonavir. New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have also been reported with use of anti-retroviral protease inhibitors, such as ritonavir. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [36111] [7238] [7335] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients, including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [28341] [30575] [36111] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30480] [30575] Metformin; Sitagliptin: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic agents should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30575] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30480] [30575] Methadone: (Major) Avoid coadministration of lopinavir with methadone due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Methadone is associated with an increased risk for QT prolongation and torsade de pointes (TdP), especially at higher doses (more than 200 mg/day but averaging approximately 400 mg/day in adult patients). Most cases involve patients being treated for pain with large, multiple daily doses of methadone, although cases have been reported in patients receiving doses commonly used for maintenance treatment of opioid addiction. [28319] [28320] [28321] [28322] [28341] [33136] [65157] [65170] (Moderate) Coadministration of ritonavir with methadone has resulted in decreased methadone plasma concentrations. However, because methadone is metabolized by multiple CYP450 enzymes, including CYP3A4, CYP2C19, CYP2C9, and CYP2D6, and ritonavir is known to inhibit CYP3A4 and CYP2D6 and induce CYP2C19 and CYP2C9, the potential for increased methadone exposure should also be considered with concomitant administration. Therefore, concurrent use may increase or prolong opioid effects, resulting in fatal overdose or may decrease methadone efficacy or produce onset of withdrawal symptoms in patients physically dependent on methadone. Monitor for respiratory depression, sedation, and signs of opioid withdrawal. Consider adjusting the methadone dose until stable drug effects are achieved. If ritonavir is discontinued, and its CYP450 effects decline, methadone plasma concentrations may increase or decrease. Closely monitor for increased opioid adverse effects and for evidence of withdrawal and adjust the methadone dose as necessary when ritonavir is discontinued. [33136] [47165] Methamphetamine: (Moderate) Warn patients that the risk of amphetamine toxicity may be increased during concurrent use of ritonavir, a strong CYP2D6 inhibitor. Amphetamines are partially metabolized by CYP2D6 and have serotonergic properties; inhibition of amphetamine metabolism may increase the risk of serotonin syndrome or other toxicity. If serotonin syndrome occurs, both the amphetamine and CYP2D6 inhibitor should be discontinued and appropriate medical treatment should be implemented. [25887] [29219] [33263] [47165] [57067] Methohexital: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] Methylergonovine: (Severe) Coadministration of ergot alkaloids with potent inhibitors of CYP3A4, like anti-retroviral protease inhibitors is considered contraindicated due to the risk of acute ergot toxicity (e.g., vasospasm leading to cerebral ischemia, peripheral ischemia and/or other serious effects). Several case reports have established the clinical significance of this interaction in the medical literature. In some cases, fatal interactions have occurred. [28142] [28341] [28731] [28839] [28995] [32432] [46638] [5018] [5044] [5623] [5747] [8102] Methylprednisolone: (Moderate) Coadministration of methylprednisolone with ritonavir may cause elevated methylprednisolone serum concentrations, potentially resulting in Cushing's syndrome and adrenal suppression. Monitor closely. For long-term use, consider an alternative corticosteroid, such as beclomethasone and prednisolone, if appropriate. whose concentrations are less affected by strong CYP3A4 inhibitors. Methylprednisolone is a CYP3A4 substrate and ritonavir is a strong inhibitor of CYP3A4. [30015] [47165] [58664] Methysergide: (Severe) Coadministration of ergot alkaloids with potent inhibitors of CYP3A4, like anti-retroviral protease inhibitors is considered contraindicated due to the risk of acute ergot toxicity (e.g., vasospasm leading to cerebral ischemia, peripheral ischemia and/or other serious effects). Several case reports have established the clinical significance of this interaction in the medical literature. In some cases, fatal interactions have occurred. [28142] [28341] [28731] [28839] [28995] [32432] [46638] [5018] [5044] [5623] [5747] [8102] Metoclopramide: (Moderate) Concurrent administration of metoclopramide with ritonavir may result in elevated plasma concentrations of metoclopramide. Metoclopromide is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [34515] [47165] [58664] Metoprolol: (Moderate) Metoprolol is significantly metabolized by CYP2D6 isoenzymes. CYP2D6 inhibitors, such as ritonavir, may impair metoprolol metabolism. Clinicians should be alert to exaggerated beta-blocker effects if metoprolol is given with these drugs. [5044] [5269] Metronidazole: (Major) Avoid coadministration of lopinavir with metronidazole due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Potential QT prolongation has been reported in limited case reports with metronidazole. Additionally, oral solutions of lopinavir; ritonavir contain ethanol which can produce disulfiram-like reactions when coadministered with metronidazole. [28341] [57377] [57378] [65157] [65170] (Major) Medications with significant alcohol content should not be ingested during therapy with metronidazole and should be avoided for 3 days after therapy is discontinued. Ritonavir oral solution and capsules contain ethanol. Administration of ritonavir oral solution or capsules to patients receiving or who have recently received disulfiram or metronidazole may result in disulfiram-like reactions. A disulfiram reaction would not be expected to occur with non-ethanol containing formulations of ritonavir (e.g., tablets, oral powder). [28315] [28581] [47165] Mexiletine: (Major) Ritonavir is an inhibitor of CYP3A4 and CYP2D6 (in vitro), and may increase exposure to drugs metabolized by these enzymes, such as mexiletine. Increased mexiletine serum concentrations may increase the risk for adverse reactions. [47165] [60002] Midazolam: (Major) The use of oral midazolam and anti-retroviral protease inhibitors is contraindicated due to the potential for serious and/or life-threatening events such as prolonged or increased sedation or respiratory depression. Parenteral midazolam can be used with protease inhibitors in a setting that allows for close clinical monitoring with the ability to manage respiratory depression or sedation should they occur; a reduction in the dose of parenteral midazolam may be warranted. Lorazepam, oxazepam, or temazepam may be safer alternatives, as these benzodiazepines are not oxidatively metabolized. Midazolam is metabolized by hepatic isozyme CYP3A4. Protease inhibitors have been shown to increase oral midazolam AUCs by up to 3-fold, resulting in clinically significant potentiation of sedation. [28142] [28341] [28731] [28839] [28995] [29012] [31320] [32432] [44859] [47165] Midostaurin: (Major) Avoid coadministration of lopinavir with midostaurin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs have been associated with QT prolongation. [28341] [61906] [65157] [65170] (Major) Avoid the concomitant use of midostaurin and ritonavir as significantly increased exposure of midostaurin and its active metabolites may occur resulting in increased toxicity. Consider an alternative agent to replace ritonavir. If coadministration cannot be avoided, monitor patients for signs and symptoms of midostaurin toxicity (e.g., gastrointestinal toxicity, hematologic toxicity, bleeding, and infection), particularly during the first week of midostaurin therapy for systemic mastocytosis/mast cell leukemia and the first week of each cycle of midostaurin therapy for acute myeloid leukemia. Midostaurin is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. The AUC values of midostaurin and its metabolites CGP62221 and CGP52421 increased by 10.4-fold, 3.5-fold, and 1.2-fold, respectively, when midostaurin was administered with another strong CYP3A4 inhibitor in a drug interaction study. The Cmin (trough) levels of midostaurin and its metabolites CGP62221 and CGP52421 on day 28 increased by 2.1-fold, 1.2-fold, and 1.3-fold, respectively, when midostaurin was administered with another strong CYP3A4 inhibitor compared with day 21 Cmin levels with midostaurin alone in another drug interaction study. [47165] [61906] Mifepristone: (Major) Avoid coadministration of lopinavir with mifepristone due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Monitor patients for lopinavir-related adverse effects (e.g., diarrhea, nausea, vomiting, fast irregular heartbeat, hypokalemia, pancreatic or hepatic dysfunction). Mifepristone is a strong CYP3A4 inhibitor and may lead to an increase in serum concentrations of lopinavir, a CYP3A4 substrate. Mifepristone is also associated with dose-related prolongation of the QT interval. Lopinavir is associated with QT prolongation. [28003] [28341] [48697] [65157] [65170] (Major) Avoid coadministration of ritonavir with mifepristone if possible because increased serum concentrations of either drug may result. The benefit of concomitant use of these agents should be carefully weighed against the potential risks. The CYP3A4 metabolism of mifepristone may be inhibited by ritonavir, a strong CYP3A4 inhibitor. In addition, mifepristone is a strong CYP3A4 inhibitor and may lead to an increase in serum concentrations of CYP3A4 substrates, such as ritonavir. When mifepristone is used in the treatment of Cushing's syndrome, coadministration with strong CYP3A inhibitors should be done only when necessary, and in such cases, the dose of mifepristone should be limited to 600 mg per day. In a patient already receiving ritonavir, initiate mifepristone at a dose of 300 mg and titrate to a maximum of 600 mg if clinically indicated. If therapy with ritonavir is initiated in a patient already receiving mifepristone 300 mg, mifepristone dosage adjustments are not required. If therapy with ritonavir is initiated in a patient already receiving mifepristone 600 mg, reduce dose of mifepristone to 300 mg and titrate to a maximum of 600 mg if clinically indicated. If therapy with ritonavir is initiated in a patient already receiving mifepristone 900 mg or 1,200 mg, reduce the mifepristone dose to 600 mg. [28003] [47165] [48697] Miglitol: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. [7238] [7335] Mirabegron: (Moderate) Concurrent administration of mirabegron with ritonavir may result in elevated plasma concentrations of ritonavir. Mirabegron is a moderate inhibitor of CYP2D6. Ritonavir is a CYP2D6 substrate. Caution and close monitoring are advised if these drugs are administered together. [28380] [47165] [51111] Mirtazapine: (Major) Avoid coadministration of lopinavir with mirtazapine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Mirtazapine has been associated with dose-dependent prolongation of the QT interval. Torsade de pointes (TdP) has been reported postmarketing, primarily in overdose or in patients with other risk factors for QT prolongation. [28341] [40942] [65157] [65170] (Moderate) The plasma concentrations of mirtazapine may be elevated when administered concurrently with ritonavir. Clinical monitoring for adverse effects, such as CNS or GI effects, is recommended during coadministration. Ritonavir is a strong CYP3A4 inhibitor, while mirtazapine is a CYP3A4. Coadministration with another strong CYP3A4 inhibitor increased mirtazapine exposure by approximately 50%. [40942] [47165] Mitotane: (Severe) Coadministration of lopinavir and mitotane is contraindicated due to the potential for reduced antiretroviral efficacy and the potential development of viral resistance. If coadministration cannot be avoided, monitor for decreased efficacy of lopinavir. Mitotane is a strong CYP3A4 inducer and lopinavir is a CYP3A4 substrate; coadministration may result in decreased plasma concentrations of lopinavir. [28341] [41934] [46638] [56579] (Major) Avoid the concomitant use of mitotane with ritonavir due to the potential for reduced antiretroviral efficacy and the potential development of viral resistance. If coadministration cannot be avoided, monitor for decreased efficacy of ritonavir. Mitotane is a strong CYP3A4 inducer and ritonavir is a CYP3A4 substrates; coadministration may result in decreased plasma concentrations of ritonavir. Another strong CYP3A inducer, rifampin (300 or 600 mg daily for 10 days), decreased the AUC and Cmax of ritonavir (500 mg every 12 hours for 20 days) by 35% and 25%, respectively. [41934] [46638] Modafinil: (Major) Concurrent administration of modafinil with ritonavir may result in elevated plasma concentrations of modafinil and decreased concentrations of ritonavir. Modafinil is a substrate and inducer of the hepatic isoenzyme CYP3A4; ritonavir is a CYP3A4 substrate. In addition, ritonavir is a potent CYP3A4 inhibitor. Because the resultant effect of coadministration of a CYP3A4 inducer (modafinil) and inhibitor (ritonavir) on the plasma concentrations of these drugs is not defined, caution and close monitoring are advised if these drugs are administered together. [41243] [58664] Mometasone: (Moderate) Coadministration of mometasone with ritonavir (a strong CYP3A4 inhibitor) may cause mometasone serum concentrations to increase, potentially resulting in Cushing's syndrome and adrenal suppression. Consider use of an alternative corticosteroid whose concentrations are less affected by strong CYP3A4 inhibitors, such as beclomethasone and prednisolone, especially during long-term treatment. [28341] [47165] [58620] Morphine: (Moderate) Close clinical monitoring is advised when administering morphine with ritonavir due to an increased potential for morphine-related adverse events, including hypotension, respiratory depression, profound sedation, coma, and death. Dosage reductions of morphine and/or ritonavir may be required. Morphine is a substrate of the drug efflux transporter P-glycoprotein (P-gp); ritonavir is an inhibitor of this efflux protein. Coadministration may cause an approximate 2-fold increase in morphine exposure. [28380] [34557] [40951] Morphine; Naltrexone: (Moderate) Close clinical monitoring is advised when administering morphine with ritonavir due to an increased potential for morphine-related adverse events, including hypotension, respiratory depression, profound sedation, coma, and death. Dosage reductions of morphine and/or ritonavir may be required. Morphine is a substrate of the drug efflux transporter P-glycoprotein (P-gp); ritonavir is an inhibitor of this efflux protein. Coadministration may cause an approximate 2-fold increase in morphine exposure. [28380] [34557] [40951] Moxifloxacin: (Major) Avoid coadministration of lopinavir with moxifloxacin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Quinolones have been associated with a risk of QT prolongation. Although extremely rare, torsade de pointes (TdP) has been reported during postmarketing surveillance of moxifloxacin. These reports generally involved patients with concurrent medical conditions or concomitant medications that may have been contributory. [28341] [28423] [5149] [5150] [65157] [65170] (Moderate) Concomitant use of ritonavir with moxifloxacin may increase ritonavir adverse effects. After 3 days of ritonavir 400 mg twice daily plus moxifloxacin (400 mg once daily), ritonavir exposure was approximately 1.5 times higher than exposure that has been observed with ritonavir 600 mg twice-daily alone. Caution and close monitoring is advised if these drugs are administered together. [47165] [60002] Nabilone: (Moderate) Coadministration of ritonavir and oral THC results in increased THC concentrations. A decreased dose of nabilone may be needed if these drugs are coadministered with ritonavir. [5044] Nadolol: (Moderate) Cardiac and neurologic events have been reported when ritonavir was concurrently administered with beta-blockers. [5044] Nafcillin: (Major) Concurrent administration of nafcillin with ritonavir may result in decreased plasma concentrations of ritonavir, which may affect antiviral efficacy. Nafcillin is an inducer of the hepatic isoenzyme CYP3A4; ritonavir is a CYP3A4 substrate. Caution and close monitoring are advised if these drugs are administered together. [11312] [11313] [58664] Naldemedine: (Major) Monitor for potential naldemedine-related adverse reactions if coadministered with ritonavir. The plasma concentrations of naldemedine may be increased during concurrent use. Naldemedine is a substrate of CYP3A4 and P-gp; ritonavir is a moderate P-gp inhibitor and a strong CYP3A4 inhibitor. [28380] [34557] [47165] [61831] Naloxegol: (Severe) Concomitant use of naloxegol with ritonavir is contraindicated. Naloxegol is metabolized primarily by CYP3A. Strong CYP3A4 inhibitors, such as ritonavir, can significantly increase exposure to naloxegol which may precipitate opioid withdrawal symptoms such as hyperhidrosis, chills, diarrhea, abdominal pain, anxiety, irritability, and yawning. [47165] [57937] Nanoparticle Albumin-Bound Paclitaxel: (Moderate) Monitor for an increase in paclitaxel-related adverse reactions if coadministration of nab-paclitaxel with ritonavir is necessary due to the risk of increased plasma concentrations of paclitaxel. Nab-paclitaxel is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. In vitro, coadministration with both strong and moderate CYP3A4 inhibitors increased paclitaxel exposure; however, the concentrations used exceeded those found in vivo following normal therapeutic doses. The pharmacokinetics of paclitaxel may also be altered in vivo as a result of interactions with CYP3A4 inhibitors. [30742] [47165] (Moderate) Monitor for paclitaxel-related adverse reactions during coadministration with lopinavir as concurrent use may increase exposure to paclitaxel. Paclitaxel is a substrate for the transporter organic anion-transporting polypeptide (OATP1B1); lopinavir is an OATP1B1 inhibitor. [28341] [30742] [56579] Nateglinide: (Moderate) Concurrent administration of nateglinide with some protease inhibitors may result in elevated nateglinide plasma concentrations via inhibition of CYP2C9. Ritonavir may induce CYP2C9 leading to a reduction of nateglinide concentrations. Monitor blood glucose concentrations during coadministration as hypoglycemia or hyperglycemia could occur. New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Monitor blood glucose concentrations during coadministration. Caution and close monitoring are advised if these drugs are administered together. [30585] [45644] [47165] Nebivolol: (Moderate) Ritonavir is expected to decrease the hepatic CYP metabolism of beta-blockers like nebivolol, resulting in increased beta-blocker concentrations. Cardiac and neurologic events have been reported when ritonavir is concurrently administered with beta-blockers. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including beta-blockers) has not been evaluated. If coadministration of nebivolol and ritonavir is warranted, do so with caution and careful monitoring. Decreased beta-blocker doses may be warranted. [28315] [60860] Nebivolol; Valsartan: (Moderate) Concurrent use of lopinavir with valsartan may result in elevated valsartan serum concentrations. Valsartan is a substrate for the drug transporter organic anion transporting polypeptide (OATP1B1/1B3); lopinavir is an OATP1B1 inhibitor. Monitor for increased toxicities if these drugs are given together. [56579] [61510] [61511] [61513] (Moderate) Ritonavir is expected to decrease the hepatic CYP metabolism of beta-blockers like nebivolol, resulting in increased beta-blocker concentrations. Cardiac and neurologic events have been reported when ritonavir is concurrently administered with beta-blockers. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including beta-blockers) has not been evaluated. If coadministration of nebivolol and ritonavir is warranted, do so with caution and careful monitoring. Decreased beta-blocker doses may be warranted. [28315] [60860] (Minor) Valsartan is a substrate of the hepatic efflux transporter MRP2 and ritonavir is an inhibitor of MRP2. Coadministration may increase systemic exposure to valsartan. Patients should be monitored for adverse effects of valsartan during coadministration. [28315] [29130] [36646] [39870] [60860] Nefazodone: (Major) Elevated plasma concentrations of nefazodone and ritonavir may occur. Both ritonavir and nefazodone are CYP3A4 substrates/potent inhibitors. Cardiac and neurologic events have been reported when ritonavir was concurrently administered with nefazodone. If coadministration of these drugs is warranted, do so with caution and careful monitoring. A 50% reduction in the nefazodone dose may be warranted. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs with potential bradycardic effects has not been evaluated. [28315] [47165] [4718] [5044] [5414] [54634] [5772] (Moderate) Elevated lopinavir plasma concentrations may occur when administered concurrently with nefazodone. Nefazodone is a potent inhibitor of CYP3A4; lopinavir is a CYP3A4 substrate. Lopinavir also prolongs the PR interval in some patients; however, the impact on the PR interval when administered with other drugs that have potential bradycardic effects has not been evaluated. [28341] [54634] Nelfinavir: (Major) Coadministration of lopinavir and nelfinavir may result in decreased concentratons of lopinavir. If coadministered, the dose of lopinavir; ritonavir must be increased and given twice daily; do not use once daily administration. Consult dosing information for recommended adjustments. [28341] (Moderate) Concurrent administration of ritonavir and nelfinavir results in a 1.5-fold increase of nelfinavir AUC. Dosage recommendations for coadministration from HIV treatment guidelines are ritonavir 400 mg twice daily plus nelfinavir 500 to 750 mg twice daily. Both ritonavir and nelfinavir are potent inhibitors and substrates of CYP3A4 and P-glycoprotein (P-gp). [11417] [11418] [28839] [46638] Neratinib: (Major) Avoid concomitant use of ritonavir with neratinib due to an increased risk of neratinib-related toxicity. Neratinib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased neratinib exposure by 381%; concomitant use with other strong inhibitors of CYP3A4 may also increase neratinib concentrations. [47165] [62127] Netupitant, Fosnetupitant; Palonosetron: (Moderate) Coadministration may result in increased netupitant and ritonavir exposure. Netupitant is a CYP3A4 substrate and moderate inhibitor of CYP3A4; the inhibitory effect on CYP3A4 can last for multiple days. Ritonavir is a CYP3A4 substrate and strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased netupitant exposure by 140%. No dosage adjustment is necessary. [47165] [58171] (Moderate) Netupitant is a moderate inhibitor of CYP3A4 and should be used with caution in patients receiving concomitant medications that are metabolized through CYP3A4 such as lopinavir; the inhibitory effect on CYP3A4 can last for multiple days. Increased lopinavir concentrations may occur and may lead to side effects, including a possible risk for QT prolongation. [28341] [58171] Nevirapine: (Major) Coadministration of lopinavir and nevirapine may result in decreased concentratons of lopinavir. If coadministered, the dose of lopinavir; ritonavir must be increased and given twice daily; do not use once daily administration. Consult dosing information for recommended adjustments. [28341] (Moderate) Concurrent administration of nevirapine with ritonavir may result in elevated nevirapine plasma concentrations and decreased concentrations of ritonavir. Nevirapine is a substrate and inducer of the hepatic isoenzyme CYP3A4; ritonavir is a substrate and potent inhibitor of this enzyme. Caution and close monitoring for antiviral efficacy and adverse effects are advised if these drugs are administered together. [5222] [58664] Niacin; Simvastatin: (Severe) The coadministration of anti-retroviral protease inhibitors with simvastatin is contraindicated. Taking these drugs together may significantly increase the serum concentration of simvastatin; thereby increasing the risk of myopathy and rhabdomyolysis. One report has demonstrated that ritonavir plus saquinavir therapy markedly increases the AUC for simvastatin by 3059%. Simvastatin is a substrate for CYP3A4 and the drug transporter organic anion transporting polypeptide (OATP1B1); protease inhibitors are CYP3A4 and OATP inhibitors. [28605] [39682] [46638] [61510] [61511] [61512] [61513] Nicardipine: (Moderate) Anti-retroviral protease inhibitors may decrease the hepatic CYP metabolism of calcium-channel blockers (mainly through CYP3A4 inhibition) resulting in increased calcium-channel blocker concentrations. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [11537] [28315] [47165] [50341] [56565] Nifedipine: (Major) According to the manufacturer of nifedipine, coadministration with ritonavir may result in increased exposure to nifedipine, and initiation of nifedipine should begin with the lowest available dose. Anti-retroviral protease inhibitors may decrease the hepatic CYP metabolism of calcium-channel blockers (mainly through CYP3A4 inhibition) resulting in increased calcium-channel blocker concentrations. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [28315] [29068] [31749] (Moderate) Lopinavir prolongs the PR interval in some patients; however, the impact on the PR interval when administered with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. Caution is warranted and clinical monitoring of the patient is recommended. [28341] [29068] [31749] Nilotinib: (Major) Avoid coadministration of lopinavir with nilotinib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Sudden death and QT interval prolongation have occurred in patients who received nilotinib therapy. [28341] [58766] [65157] [65170] (Major) Avoid the concomitant use of nilotinib and ritonavir. If coadministration is required, monitor patients closely for prolongation of the QT interval and reduce the nilotinib dose to 300 mg once daily in patients with resistant or intolerant Ph+ CML or to 200 mg once daily in patients with newly diagnosed Ph+ CML. If ritonavir is discontinued, a washout period should be allowed before adjusting the nilotinib dosage upward to the indicated dose. Nilotinib is a substrate and moderate inhibitor of CYP3A4 and ritonavir is a substrate and a strong inhibitor of CYP3A4. [28315] [47165] [58766] Nimodipine: (Moderate) Anti-retroviral protease inhibitors are CYP3A4 inhibitors and may decrease the hepatic metabolism of nimodipine, leading to increased plasma concentrations of nimodipine. In addition, ritonavir and calcium channel blockers both prolong the PR interval and the manufacturer for ritonavir recommends caution during coadministration. Monitor therapeutic response and for adverse effects, such as hypotension. Decreased calcium-channel blocker doses may be warranted. [28315] [29082] [32432] [47165] Nintedanib: (Moderate) Dual inhibitors of P-glycoprotein (P-gp) and CYP3A4, such as ritonavir, are expected to increase the exposure and clinical effect of nintedanib. If use together is necessary, closely monitor for increased nintedanib side effects including gastrointestinal toxicity (nausea, vomiting, diarrhea, abdominal pain, loss of appetite), headache, elevated liver enzymes, and hypertension. A dose reduction, interruption of therapy, or discontinuation of nintedanib therapy may be necessary. Ritonavir is a potent CYP3A4 inhibitor and a P-gp inhibitor; nintedanib is a P-gp substrate and a minor CYP3A4 substrate. In drug interactions studies, administration of nintedanib with a dual P-gp and CYP3A4 inhibitor increased nintedanib AUC by 60%. [28341] [38968] [47165] [58203] Nisoldipine: (Moderate) Anti-retroviral protease inhibitors may decrease the hepatic CYP metabolism of calcium-channel blockers (mainly through CYP3A4 inhibition) resulting in increased calcium-channel blocker concentrations. In addition, ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [28315] [32432] [47165] Norethindrone: (Moderate) Many anti-retroviral protease inhibitors may interact with hormonal agents like norethindrone, due to their actions on CYP metabolism, particularly CYP3A4. Data on the effects that protease inhibitors have on the serum concentrations of norethindrone are complex and are based mostly off of data with norethindrone-containing contraceptives. For example, ritonavir (also found in combinations like lopinavir; ritonavir, and used as a booster in many HIV treatment regimens) may decrease the metabolism of norethindrone, raising norethindrone concentrations. Women receiving norethindrone for hormone replacement or contraception should report potential hormonal adverse effects (e.g., bleeding pattern changes, acne, emotional lability) or any changes in efficacy (e.g., noted changes in bleeding patterns) to their prescribers. Because norethindrone-containing contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive norethindrone contraception concurrently with ritonavir should use an additional barrier method of contraception such as condoms. [58679] [7731] Norfloxacin: (Major) Avoid coadministration of lopinavir with norfloxacin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Quinolones have been associated with a risk of QT prolongation and torsade de pointes (TdP). Although extremely rare, TdP has been reported during postmarketing surveillance of norfloxacin. These reports generally involved patients with concurrent medical conditions or concomitant medications that may have been contributory. [28225] [28341] [28432] [28457] [29818] [65157] [65170] Nortriptyline: (Moderate) A dose reduction of the tricyclic antidepressant (TCA) may be necessary when coadministered with ritonavir. Concurrent use may result in elevated TCA plasma concentrations. [47165] Octreotide: (Major) Avoid coadministration of lopinavir with octreotide due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Arrhythmias, sinus bradycardia, and conduction disturbances have occurred during octreotide therapy. Since bradycardia is a risk factor for development of torsade de pointes (TdP), the potential occurrence of bradycardia during octreotide administration could theoretically increase the risk of TdP in patients receiving drugs that prolong the QT interval. [28341] [4951] [65157] [65170] Ofloxacin: (Major) Avoid coadministration of lopinavir with ofloxacin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Quinolones have been associated with a risk of QT prolongation and torsade de pointes (TdP). Although extremely rare,TdP has been reported during postmarketing surveillance of ofloxacin. These reports generally involved patients with concurrent medical conditions or concomitant medications that may have been contributory. [28341] [30738] [65157] [65170] Olanzapine: (Major) Avoid coadministration of lopinavir with olanzapine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Limited data, including some case reports, suggest that olanzapine may be associated with a significant prolongation of the QTc interval. [28341] [28785] [32732] [32734] [32745] [32746] [65157] [65170] (Moderate) Ritonavir may reduce olanzapine serum concentrations by approximately 50%; how this affects olanzapine efficacy, however, is not known. Ritonavir appears to induce olanzapine's metabolism by either CYP1A2 or glucuronide conjugation. If ritonavir and olanzapine are used concurrently, monitor for reduced olanzapine effect and adjust olanzapine dose as needed. [27275] Olaparib: (Major) Avoid coadministration of olaparib with ritonavir due to the risk of increased olaparib-related adverse reactions. If concomitant use is unavoidable, reduce the dose of olaparib to 100 mg twice daily; the original dose may be resumed 3 to 5 elimination half-lives after ritonavir is discontinued. Olaparib is a CYP3A substrate and ritonavir is a strong CYP3A4 inhibitor; concomitant use may increase olaparib exposure. Coadministration with another strong CYP3A inhibitor increased the olaparib Cmax by 42% and the AUC by 170%. [28380] [34557] [47165] [58662] Olodaterol: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] (Moderate) Beta-agonists, such as olodaterol, may be associated with adverse cardiovascular effects including QT interval prolongation. Beta-agonists should be administered with extreme caution to patients being treated with drugs known to prolong the QT interval because the action of beta-agonists on the cardiovascular system may be potentiated. Drugs with a possible risk for QT prolongation and TdP that should be used cautiously and with close monitoring with olodaterol include ritonavir. [47165] [57710] Ombitasvir; Paritaprevir; Ritonavir: (Major) Avoid coadministration of lopinavir with paritaprevir. Use of these drugs in combination has resulted in elevated paritaprevir serum concentrations. Paritaprevir is a substrate of the drugs transporter organic anion transporting polypeptide (OATP1B1); lopinavir is an OATP1B1 inhibitor. [58664] [61510] [61511] [61513] Omeprazole: (Moderate) Increased exposure to omeprazole may occur during concurrent administration of ritonavir. Although dosage adjustment of omeprazole is not normally required, dosage reduction may be considered in patients receiving higher omeprazole doses (e.g., those with Zollinger-Ellison syndrome). Ritonavir is a strong CYP3A4 inhibitor. Omeprazole is a CYP2C19 and CYP3A4 substrate. Coadministration of a dual CYP2C19/strong CYP3A4 inhibitor increased the omeprazole AUC by an average of 4-times. [29564] [47165] Omeprazole; Amoxicillin; Rifabutin: (Major) Coadministration of ritonavir and rifabutin results in clinically significant alterations of rifabutin pharmacokinetic parameters, with the rifabutin AUC being increased by 430%. In patients receiving any dosage of ritonavir, the dose of rifabutin should always be decreased to 150 mg every day or 300 mg three times per week. [46638] (Major) If lopinavir and rifabutin are administered concurrently, the manufacturer recommends a rifabutin dose reduction of at least 75% of the usual dose (i.e., a maximum dose of 150 mg every other day or 3 times per week). In addition, increase monitoring for adverse reactions is recommended. Use of these drugs together increases the AUC of rifabutin and it's metabolites. [28341] [46638] (Moderate) Increased exposure to omeprazole may occur during concurrent administration of ritonavir. Although dosage adjustment of omeprazole is not normally required, dosage reduction may be considered in patients receiving higher omeprazole doses (e.g., those with Zollinger-Ellison syndrome). Ritonavir is a strong CYP3A4 inhibitor. Omeprazole is a CYP2C19 and CYP3A4 substrate. Coadministration of a dual CYP2C19/strong CYP3A4 inhibitor increased the omeprazole AUC by an average of 4-times. [29564] [47165] Omeprazole; Sodium Bicarbonate: (Moderate) Concurrent administration of tipranavir and ritonavir with antacids results in decreased tipranavir concentrations. Administer tipranavir and ritonavir 2 hours before or 1 hour after antacids. [1800] [1802] (Moderate) Increased exposure to omeprazole may occur during concurrent administration of ritonavir. Although dosage adjustment of omeprazole is not normally required, dosage reduction may be considered in patients receiving higher omeprazole doses (e.g., those with Zollinger-Ellison syndrome). Ritonavir is a strong CYP3A4 inhibitor. Omeprazole is a CYP2C19 and CYP3A4 substrate. Coadministration of a dual CYP2C19/strong CYP3A4 inhibitor increased the omeprazole AUC by an average of 4-times. [29564] [47165] Ondansetron: (Major) Avoid coadministration of lopinavir with ondansetron due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Ondansetron has been associated with a dose-related increase in the QT interval and postmarketing reports of torsade de pointes (TdP). [28341] [31266] [65157] [65170] (Moderate) Caution and close monitoring are advised if these drugs are administered together. Ondansetron exposure may be altered resulting in increased adverse effects or decreased efficacy. Ondansetron is metabolized by the hepatic isoenzymes CYP3A4, CYP2D6, and CYP1A2; ritonavir inhibits CYP3A4 and CYP2D6 and induces CYP1A2. [31266] [47165] Oritavancin: (Major) Ritonavir is metabolized by CYP3A4 and CYP2D6 (minor); oritavancin is a weak CYP3A4 and CYP2D6 inducer. Plasma concentrations and efficacy of ritonavir may be reduced if these drugs are administered concurrently. [27493] [27494] [34557] [57741] (Moderate) Lopinavir is metabolized by CYP3A4; oritavancin is a weak CYP3A4 inducer. Plasma concentrations and efficacy of lopinavir may be reduced if these drugs are administered concurrently. [27493] [27494] [28341] [57741] Orlistat: (Major) According to the manufacturer of orlistat, HIV RNA levels should be frequently monitored in patients receiving orlistat while being treated for HIV infection with anti-retroviral protease inhibitors. Loss of virological control has been reported in HIV-infected patients taking orlistat with atazanavir, ritonavir, tenofovir disoproxil fumarate, emtricitabine, lopinavir; ritonavir, and emtricitabine; efavirenz; tenofovir disoproxil fumarate. The exact mechanism for this interaction is not known, but may involve inhibition of systemic absorption of the anti-retroviral agent. If an increased HIV viral load is confirmed, orlistat should be discontinued. [27971] Osilodrostat: (Major) Avoid coadministration of lopinavir with osilodrostat due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Osilodrostat is associated with dose-dependent QT prolongation. [28341] [65098] [65157] [65170] (Major) Reduce the dose of osilodrostat by one-half during coadministration of ritonavir; concurrent use may increase osilodrostat exposure and the risk of osilodrostat-related adverse reactions. Osilodrostat is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. [47165] [65098] Osimertinib: (Major) Avoid coadministration of lopinavir with osimertinib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Interrupt or dose reduce osimertinib if QT prolongation occurs. Concentration-dependent QTc prolongation occurred during clinical trials of osimertinib. Lopinavir is associated with QT prolongation. [28341] [60297] [65157] [65170] Ospemifene: (Major) Use caution when administering ospemifene to a patient taking ritonavir, as concurrent use may increase ospemifene systemic exposure and increase the risk of ospemifene-related adverse reactions. Consider if alternative therapy is appropriate. Ritonavir is a strong CYP3A4 inhibitor and a CYP2C9 inhibitor, and ospemifene is a CYP3A4 and CYP2C9 substrate. Co-administration of ospemifene with a drug known to inhibit CYP3A4 and CYP2C9 isoenzymes increased the ospemifene exposure 2.7-fold. [47165] [53344] Oxaliplatin: (Major) Avoid coadministration of lopinavir with oxaliplatin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. QT prolongation and ventricular arrhythmias including fatal torsade de pointes have been reported with oxaliplatin use in postmarketing experience. [28341] [41958] [65157] [65170] Oxcarbazepine: (Major) Concurrent administration of oxcarbazepine with ritonavir should be undertaken with caution and careful monitoring of antiviral efficacy. Oxcarbazepine is a moderate inducer of the hepatic isoenzyme CYP3A4, and ritonavir is a CYP3A4 substrate. [29014] [58664] Oxybutynin: (Moderate) Oxybutynin is metabolized by CYP3A4. Caution should be used when oxybutynin is given in combination with inhibitors of CYP3A4, such as protease inhibitors. Monitor for adverse effects if these drugs are administered together. [29796] [47165] [58664] Oxycodone: (Moderate) Consider a reduced dose of oxycodone with frequent monitoring for respiratory depression and sedation if concurrent use of ritonavir is necessary. If ritonavir is discontinued, consider increasing the oxycodone dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oxycodone is a CYP3A4 substrate, and coadministration with a strong CYP3A4 inhibitor like ritonavir can increase oxycodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of oxycodone. If ritonavir is discontinued, oxycodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to oxycodone. [39926] [47165] Oxymorphone: (Moderate) Ritonavir is an inhibitor of the cytochrome P450 3A4 isoenzyme and may decrease the metabolism of oxymorphone if the two drugs are coadministered. [4718] Ozanimod: (Major) Avoid coadministration of lopinavir with ozanimod due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Ozanimod initiation may result in a transient decrease in heart rate and atrioventricular conduction delays. Ozanimod has not been studied in patients taking concurrent QT prolonging drugs; however, QT prolonging drugs have been associated with torsade de pointes in patients with bradycardia. [28341] [65157] [65169] [65170] Paclitaxel: (Minor) Due to ritonavir's potential inhibitory effects on various hepatic isoenzymes, numerous drug interactions may occur with ritonavir. Close monitoring of serum drug concentrations and/or therapeutic and adverse effects is required when paclitaxel (a CYP2C8 and CYP3A4 substrate) is coadministered with ritonavir (a CYP3A4 inhibitor). In addition, paclitaxel is a substrate of the drug transporter P-glycoprotein (P-gp), and ritonavir also inhibits P-gp. [28001] [28341] [28380] [28498] [49806] [56579] [58664] Palbociclib: (Major) Avoid coadministration of ritonavir with palbociclib; significantly increased plasma exposure of palbociclib may occur. If concomitant use cannot be avoided, reduce the dose of palbociclib to 75 mg PO once daily and monitor for increased adverse reactions. If ritonavir is discontinued, increase the palbociclib dose (after 3 to 5 half-lives of ritonavir) to the dose used before initiation of ritonavir. Palbociclib is primarily metabolized by CYP3A4 and ritonavir is a strong CYP3A4 inhibitor. In a drug interaction trial, coadministration with another strong CYP3A4 inhibitor increased the AUC and Cmax of palbociclib by 87% and 34%, respectively. [47165] [58768] [64721] (Moderate) Concentrations of lopinavir may increase when adminstered concurrently with palbociclib. Palbociclib is a weak, time-dependent inhibitor of CYP3A and lopinavir is a sensitive CYP3A4 substrate. [28341] [56579] [58768] [64721] Paliperidone: (Major) Avoid coadministration of lopinavir with paliperidone due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Paliperidone has been associated with QT prolongation; torsade de pointes and ventricular fibrillation have been reported in the setting of overdose. [28341] [40936] [65157] [65170] Panobinostat: (Major) Avoid coadministration of lopinavir with panobinostat due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs have been associated with QT prolongation. [28341] [58821] [65157] [65170] (Major) Reduce the starting dose of panobinostat to10 mg when coadministered with ritonavir. Concurrent use may increase systemic exposure of panobinostat. Panobinostat is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased the AUC of panobinostat by 73%. [47165] [58821] Paricalcitol: (Moderate) Paricalcitol is partially metabolized by CYP3A4. Care should be taken when dosing paricalcitol with strong CYP3A4 inhibitors, such as protease inhibitors. Dose adjustments of paricalcitol may be required. Monitor plasma PTH and serum calcium and phosphorous concentrations if a patient initiates or discontinues therapy with this combination. [42290] Paroxetine: (Major) A dose reduction of paroxetine may be necessary during co-administration of ritonavir. Concurrent use of CYP2D6 substrates, such as paroxetine, with ritonavir could result in increases (up to 2-fold) in the AUC of paroxetine. Paroxetine is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [28260] [60002] Pasireotide: (Major) Avoid coadministration of lopinavir with pasireotide due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. QT prolongation has occurred with pasireotide at therapeutic and supratherapeutic doses. [28341] [52611] [65157] [65170] Pazopanib: (Major) Avoid coadministration of lopinavir with pazopanib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs have been associated with QT prolongation. [28341] [37098] [65157] [65170] (Major) Avoid coadministration of pazopanib and ritonavir due to the potential for increased pazopanib exposure. If concurrent use is unavoidable, reduce the pazopanib dose to 400 mg PO once daily; further dose adjustments may be necessary if adverse effects occur. Pazopanib is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Concurrent use of another strong CYP3A4 inhibitor increased the Cmax and AUC of pazopanib by 1.5-fold and 1.7-fold, respectively. [37098] [47165] Pemigatinib: (Major) Avoid coadministration of pemigatinib and ritonavir due to the risk of increased pemigatinib exposure which may increase the risk of adverse reactions. If coadministration is unavoidable, reduce the dose of pemigatinib to 9 mg PO once daily if original dose was 13.5 mg per day and to 4.5 mg PO once daily if original dose was 9 mg per day. If ritonavir is discontinued, resume the original pemigatinib dose after 3 elimination half-lives of ritonavir. Pemigatinib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased pemigatinib exposure by 88%. [47165] [65307] Penbutolol: (Moderate) Cardiac and neurologic events have been reported when ritonavir was concurrently administered with beta-blockers. [5044] Pentamidine: (Major) Avoid coadministration of lopinavir with systemic pentamidine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Systemic pentamidine and lopinavir have been associated with QT prolongation. [23620] [23778] [28341] [28419] [28879] [65157] [65170] Pentobarbital: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] Perampanel: (Moderate) Concurrent use of perampanel with ritonavir may decrease ritonavir concentrations and increase perampanel concentrations. Both drugs are metabolized by CYP3A4. Ritonavir is also a CYP3A4 inhibitor, while perampanel is a weak inducer of CYP3A4. Monitor patients for increases in adverse effects such as anger, anxiety, irritability, somnolence, dizziness, or nausea. Dose adjustment may be required. [51834] [52140] Pergolide: (Severe) Coadministration of ergot alkaloids with potent inhibitors of CYP3A4, like anti-retroviral protease inhibitors is considered contraindicated due to the risk of acute ergot toxicity (e.g., vasospasm leading to cerebral ischemia, peripheral ischemia and/or other serious effects). Several case reports have established the clinical significance of this interaction in the medical literature. In some cases, fatal interactions have occurred. [28142] [28341] [28731] [28839] [28995] [32432] [46638] [5018] [5044] [5623] [5747] [8102] Perindopril; Amlodipine: (Moderate) Amlodipine is a CYP3A4 substrate. Theoretically, CYP3A4 inhibitors, such as anti-retroviral protease inhibitors, may increase the plasma concentration of amlodipine via CYP3A4 inhibition; this effect might lead to hypotension in some individuals. Caution should be used when anti-retroviral protease inhibitors are coadministered with amlodipine; therapeutic response should be monitored. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [29090] [47165] [58664] Perphenazine: (Major) Avoid coadministration of lopinavir with perphenazine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Perphenazine is associated with a possible risk for QT prolongation. [28341] [28415] [65157] [65170] Perphenazine; Amitriptyline: (Major) Avoid coadministration of lopinavir with perphenazine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Perphenazine is associated with a possible risk for QT prolongation. [28341] [28415] [65157] [65170] (Moderate) A dose reduction of the tricyclic antidepressant (TCA) may be necessary when coadministered with ritonavir. Concurrent use may result in elevated TCA plasma concentrations. [47165] Pexidartinib: (Major) Avoid coadministration of pexidartinib with ritonavir as concurrent use may increase exposure to pexidartinib and decrease exposure to ritonavir. If concurrent use cannot be avoided, reduce the dose of pexidartinib and monitor patients for a loss of ritonavir efficacy. If ritonavir is discontinued, increase the pexidartinib dose to the original dose after 3 plasma half-lives of ritonavir. Dose adjustments are as follows: 800 mg/day or 600 mg/day of pexidartinib, reduce to 200 mg twice daily; 400 mg/day of pexidartinib, reduce to 200 mg once daily. Both drugs are CYP3A4 substrates. Additionally, pexidartinib is a moderate CYP3A4 inducer and ritonavir is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased pexidartinib exposure by 70%. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. [47165] [64535] Phenobarbital: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] Phentermine; Topiramate: (Moderate) Concurrent administration of topiramate with ritonavir may result in decreased concentrations of ritonavir. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Ritonavir is metabolized by this enzyme. Caution and close monitoring are advised if these drugs are administered together. [28378] [57036] [58664] Phenylephrine; Promethazine: (Major) Avoid coadministration of lopinavir with promethazine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Promethazine, a phenothiazine, is also associated with a possible risk for QT prolongation. [28225] [28341] [55578] [65157] [65170] Phenytoin: (Major) Concurrent use of ritonavir with ethotoin, phenytoin, or fosphenytoin should be avoided when possible. Increased doses of anticonvulsants may be required due to metabolism induction by ritonavir. Additionally, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [28315] [46638] Pimavanserin: (Major) Avoid coadministration of lopinavir with pimavanserin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs are associated with QT prolongation. [28341] [60748] [65157] [65170] (Major) Reduce the dose of pimavanserin to 10 mg PO once daily and monitor for pimavanserin-related adverse reactions, including nausea, vomiting, confusion, loss of balance or coordination, and QT prolongation if coadministration with ritonavir is necessary. Concurrent use may increase pimavanserin exposure. Pimavanserin is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. In drug interaction studies, coadministration with a strong CYP3A4 inhibitor increased exposure to pimavanserin by 3-fold. [47165] [60748] Pimozide: (Severe) Coadministration of pimozide with protease inhibitors is contraindicated due to the risk of life threatening arrhythmias such as torsade de pointes (TdP). Pimozide is thought to be metabolized through CYP3A4, and to a lesser extent CYP1A2 and CYP2D6. Elevated pimozide plasma levels are probable when coadministered with CYP450 inhibitors, such as the protease inhibitors. Increased plasma concentrations of pimozide have been associated with QT prolongation and serious cardiovascular adverse events including death due to TdP. [43463] Pindolol: (Moderate) Ritonavir is expected to decrease the hepatic CYP metabolism of pindolol, resulting in increased beta-blocker concentrations. Cardiac and neurologic events have been reported when ritonavir is concurrently administered with beta-blockers. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including beta-blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased beta-blocker doses may be warranted. [28315] Pirbuterol: (Major) Avoid coadministration of lopinavir with short-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28341] [33925] [65157] [65170] Pirfenidone: (Moderate) Concurrent administration of pirfenidone with ritonavir may result in elevated plasma concentrations of ritonavir. Pirfenidone is a mild inhibitor of CYP3A4 and the drug transporter P-glycoprotein (P-gp); ritonavir is a substrate of both CYP3A4 and P-gp. Monitor for antiviral adverse effects if these drugs are administered together. [58189] [58664] Pitolisant: (Major) Avoid coadministration of lopinavir with pitolisant due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs have been associated with QT prolongation. [28341] [64562] [65157] [65170] Polatuzumab Vedotin: (Moderate) Monitor for increased polatuzumab vedotin toxicity during coadministration of ritonavir due to the risk of elevated exposure to the cytotoxic component of polatuzumab vedotin, MMAE. MMAE is metabolized by CYP3A4; ritonavir is a strong CYP3A4 inhibitor. Strong CYP3A4 inhibitors are predicted to increase the exposure of MMAE by 45%. [47165] [64290] Pomalidomide: (Moderate) Use pomalidomide and ritonavir together with caution; decreased pomalidomide exposure may occur resulting in reduced pomalidomide effectiveness. Pomalidomide is a CYP1A2 substrate and ritonavir is a CYP1A2 inducer. [28315] [59487] Ponatinib: (Major) Concomitant use of ponatinib, a CYP3A4 substrate, and ritonavir, a strong CYP3A4 inhibitor, may increase the exposure of ponatinib. If the use of both agents is necessary, reduce the starting ponatinib dose to 30 mg/day. Additionally, ponatinib is a P-gp inhibitor and may increase the plasma concentration of a P-gp substrate such as, ritonavir. [11416] [28315] [5110] [52603] Posaconazole: (Major) Avoid coadministration of lopinavir with posaconazole due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Posaconazole has been associated with prolongation of the QT interval as well as rare cases of torsade de pointes (TdP). [28341] [32723] [65157] [65170] (Moderate) Perform frequent monitoring of adverse effects and toxicity of ritonavir during coadministration with posaconazole. These drugs used in combination may result in elevated ritonavir plasma concentrations, causing an increased risk for ritonavir-related adverse events. Data from one study found the Cmax and AUC of ritonavir increased by 49% and 80%, respectively, when administered with posaconazole. [32723] Pralsetinib: (Major) Avoid coadministration of ritonavir with pralsetinib due to the risk of increased pralsetinib exposure which may increase the risk of adverse reactions. If concomitant use is unavoidable, reduce the dose of pralsetinib to 200 mg once daily for patients taking a daily dose of 400 mg or 300 mg, and to 100 mg once daily for patients taking a daily dose of 200 mg. After ritonavir has been discontinued for 3 to 5 elimination half-lives, resume the pralsetinib dose taken prior to initiating ritonavir. Pralsetinib is a CYP3A and P-glycoprotein (P-gp) substrate and ritonavir is a combined P-gp and strong CYP3A inhibitor. Coadministration with another combined P-gp and strong CYP3A inhibitor increased the AUC of pralsetinib by 251%. [28380] [34557] [47165] [65884] Pramlintide: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. [30575] [51227] Praziquantel: (Moderate) Monitor for increased side effects of praziquantel if administered with ritonavir. Concurrent administration may result in elevated praziquantel plasma concentrations. Praziquantel is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. [27480] [34457] [34458] [34459] [47165] [58664] Prednisolone: (Moderate) Ritonavir inhibits CYP3A4, and prednisolone is a CYP3A4 substrate. Monitor patients for corticosteroid-related side effects if prednisone or prednisolone and ritonavir are taken. [4194] [58664] Prednisone: (Moderate) Coadministration of prednisone with ritonavir (a strong CYP3A4 inhibitor) may cause prednisone serum concentrations to increase, potentially resulting in Cushing's syndrome and adrenal suppression. Consider use of an alternative corticosteroid whose concentrations are less affected by strong CYP3A4 inhibitors, such as beclomethasone and prednisolone, especially during long-term treatment. [47165] [58664] Primaquine: (Major) Avoid coadministration of lopinavir with primaquine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs are associated with QT prolongation. [28341] [41984] [65157] [65170] Primidone: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] Procainamide: (Major) Avoid coadministration of lopinavir with procainamide due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Procainamide is associated with a well-established risk of QT prolongation and torsade de pointes (TdP). [28250] [28341] [65157] [65170] Prochlorperazine: (Major) Avoid coadministration of lopinavir with prochlorperazine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Prochlorperazine is associated with a possible risk for QT prolongation. [28225] [28341] [28415] [65157] [65170] Progesterone: (Moderate) Use caution if coadministration of ritonavir with progesterone is necessary, as the systemic exposure of progesterone may be increased resulting in an increase in treatment-related adverse reactions. Ritonavir is a strong CYP3A4 inhibitor. Progesterone is metabolized primarily by hydroxylation via a CYP3A4. This interaction does not apply to vaginal preparations of progesterone (e.g., Crinone, Endometrin). [47165] [63694] Promethazine: (Major) Avoid coadministration of lopinavir with promethazine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Promethazine, a phenothiazine, is also associated with a possible risk for QT prolongation. [28225] [28341] [55578] [65157] [65170] Propafenone: (Major) Avoid coadministration of lopinavir with propafenone due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Propafenone is a Class IC antiarrhythmic which increases the QT interval, but largely due to prolongation of the QRS interval. [28287] [28341] [65157] [65170] (Major) Coadministration of HIV treatment doses of ritonavir and propafenone is contraindicated due to the potential for serious or life-threatening reactions, such as cardiac arrhythmias. However, propafenone and ritonavir may be coadministered with caution to patients receiving ritonavir as a boosting agent. Ritonavir inhibits both CYP3A4 and CYP2D6. Drugs that inhibit both pathways are expected to increase propafenone serum concentrations. [28287] [28315] [46638] [58664] Propofol: (Moderate) Use caution if ritonavir is coadministered with propofol due to the potential for decreased propofol exposure which may decrease its efficacy. Propofol is a CYP2B6 substrate and ritonavir is a CYP2B6 inducer. [47165] [65210] [65225] Propoxyphene: (Moderate) Due to effects on microsomal isoenzymes responsible for hepatic metabolism, ritonavir may alter the response and/or increase the AUC of opiate analgesics. Concurrent use of ritonavir and propoxyphene is not recommended, due the increased formation of the neurotoxic metabolites of propoxyphene. Also, propoxyphene is a substrate/inhibitor of CYP3A4. Increased serum concentrations of propoxyphene can occur from concurrent use of ritonavir, a CYP3A4 inhibitor. A reduced dosage of propoxyphene may be needed. Monitor for CNS and respiratory depression. [11379] [36008] [4718] [5044] Propranolol: (Moderate) Concurrent administration of propranolol with ritonavir may result in elevated propranolol plasma concentrations. Cardiac and neurologic events have been reported when ritonavir is concurrently administered with beta-blockers. Propranolol is metabolized by the hepatic isoenzyme CYP2D6; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. Decreased beta-blocker dosage may be needed. [28315] [47165] [4998] [58664] Protriptyline: (Moderate) A dose reduction of the tricyclic antidepressant (TCA) may be necessary when coadministered with ritonavir. Concurrent use may result in elevated TCA plasma concentrations. [47165] Quazepam: (Major) CYP3A4 inhibitors, such as protease inhibitors, may reduce the metabolism of quazepam and increase the potential for benzodiazepine toxicity. A decrease in the quazepam dose may be needed. [28001] [28345] [32432] Quetiapine: (Major) Avoid coadministration of lopinavir with quetiapine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Limited data, including some case reports, suggest that quetiapine may be associated with a significant prolongation of the QTc interval in rare instances. [28341] [29118] [33068] [33072] [33074] [65157] [65170] (Major) The manufacturer of quetiapine recommends a quetiapine dose reduction to one-sixth the original dose during concurrent administration of strong CYP3A4 inhibitors, such as ritonavir. When ritonavir is discontinued, the dose should be increased by 6-fold. The plasma concentrations of quetiapine may be elevated when administered concurrently with ritonavir. [29118] [47165] Quinidine: (Major) Avoid coadministration of lopinavir with quinidine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Quinidine administration is associated with QT prolongation and torsade de pointes (TdP). [28341] [42280] [47357] [65157] [65170] (Major) Coadministration of HIV treatment doses of ritonavir and quinidine is contraindicated due to the potential for serious or life-threatening reactions, such as cardiac arrhythmias. Cautious consideration may be given to administering quinidine with boosting doses of ritonavir. Ritonavir is an inhibitor of CYP3A4 and increased plasma concentrations of drugs extensively metabolized by this enzyme, such as quinidine, should be expected with concurrent use. [28315] [42280] [46638] [47165] [47357] Quinine: (Major) Avoid coadministration of lopinavir with quinine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Quinine has been associated with QT prolongation and rare cases of torsade de pointes (TdP). [28341] [31403] [65157] [65170] (Major) Concomitant use of quinine and ritonavir should be avoided due to increased quinine concentrations. In a study of healthy patients who received a single oral 600 mg dose of quinine with the 15th dose of ritonavir (200 mg PO Q12h for 9 days), there was a 4-fold increase in the mean quinine AUC and Cmax and an increase in the mean quinine elimination half-life (13.4 h vs. 11.2 h) when compared to quinine administered alone. There were no significant changes in the ritonavir pharmacokinetics. Ritonavir is a potent CYP3A4 inhibitor and quinine is a CYP3A4 substrate. [11191] [28315] [31403] [38968] Rabeprazole: (Minor) Concurrent administration of rabeprazole with ritonavir may result in increased rabeprazole plasma concentrations; however, the clinical significance of this interaction is unclear. Rabeprazole is metabolized by the hepatic isoenzymes CYP2C19 and CYP3A4; ritonavir is a potent inhibitor of CYP3A4. Monitor for rabeprazole-associated adverse events if these drugs are administered together. [40337] [41276] [58664] Ramelteon: (Moderate) The serum concentrations of ramelteon may increase when ramelteon is administered with strong CYP3A4 inhibitors like the anti-retroviral protease inhibitors. Because there is the potential for multiple CYPP450 enzyme inhibition interactions between protease inhibitors and ramelteon, caution should be used if these 2 drugs are coadministered. The patient should be monitored closely for toxicity even though ramelteon has a wide therapeutic index. [31359] [31360] [4718] [5074] [8143] [8145] Ranolazine: (Severe) Coadministration of lopinavir; ritonavir with ranolazine is contraindicated due to the potential for additive QT prolongation. Ranolazine is highly dependent on CYP3A for clearance and is associated with dose- and plasma concentration-related increases in the QTc interval. Lopinavir; ritonavir is a potent CYP3A inhibitor and is also associated with QT prolongation. [28341] [31938] (Severe) Concomitant use of ranolazine with ritonavir is contraindicated due to the potential for increased ranolazine plasma concentrations and therefore increased risk of QTc prolongation and possibly torsade de pointes. Ranolazine is a CYP3A4, CYP2D6, and P-glycoprotein (P-gp) substrate; ritonavir is a strong inhibitor of CYP3A4 and an inhibitor of CYP2D6 and P-gp. Coadministration of another strong CYP3A4 inhibitor increased plasma concentrations of ranolazine by 220%. [31938] [47165] Red Yeast Rice: (Severe) The risk of myopathy, including rhabdomyolysis, may be increased when anti-retroviral protease inhibitors are given in combination with most HMG-CoA reductase inhibitors. Since compounds in red yeast rice claim to have HMG-CoA reductase inhibitor activity, coadministration of red yeast rice with anti-retroviral protease inhibitors is not recommended. [5335] [5911] Regorafenib: (Major) Avoid coadministration of regorafenib with ritonavir due to increased plasma concentrations of regorafenib and decreased plasma concentrations of the active metabolites M-2 and M-5, which may lead to increased toxicity. Regorafenib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased regorafenib exposure by 33% and decreased exposure of M-2 and M-5 by 93% each. [47165] [51883] Remifentanil: (Moderate) Ritonavir is an inhibitor of the cytochrome P450 3A4 isoenzyme and may decrease the metabolism of remifentanil if the two drugs are coadministered. [4718] Repaglinide: (Moderate) Coadministration of repaglinide and protease inhibitors may increase or decrease glucose concentrations and increase repaglinide AUC; if coadministration is necessary, repaglinide dosage adjustment may be necessary and increased frequency of glucose monitoring is recommended. New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. In addition, repaglinide is a substrate of the hepatic isoenzyme CYP3A4 and the drug transporter organic anion transporting polypeptide (OATP1B1); protease inhibitors are potent CYP3A4 inhibitors and inhibitors of OATP. [29751] [31281] [36049] [61511] [61513] Retapamulin: (Moderate) Coadministration of retapamulin with strong CYP3A4 inhibitors, such as ritonavir, in patients younger than 24 months is not recommended. Systemic exposure of topically administered retapamulin may be higher in patients younger than 24 months than in patients 2 years and older. Retapamulin is a CYP3A4 substrate. [33239] [47165] Revefenacin: (Major) Coadministration of revefenacin is not recommended with lopinavir because it could lead to an increase in systemic exposure of the active metabolite of revefenacin and an increased potential for anticholinergic adverse effects. The active metabolite of revefenacin is a substrate of OATP1B1 and OATP1B3; lopinavir is an inhibitor of OATP1B1. [28341] [56579] [61511] [61513] [63742] Ribavirin: (Major) The concomitant use of ribavirin and anti-retroviral protease inhibitors should be done with caution as both can cause hepatic damage. Most protease inhibitors have been associated with episodes of liver toxicity, with lopinavir/low-dose ritonavir, fosamprenavir/low-dose ritonavir, and nelfinavir being less hepatotoxic and tipranavir/low-dose ritonavir being the most hepatotoxic. Hyperbilirubinemia is often associated with atazanavir and/or indinavir therapy but does not reflect liver damage and is related to the inhibition of UDP glucuronosyltransferase. Overall, the HCV-HIV International Panel recommends the management of hepatotoxicity should be based on the knowledge of the mechanisms involved for each drug. Furthermore, they state that there are lower rates of liver-related mortality in coinfected patients taking HAART, even in those with end-stage liver disease, compared with patients not receiving HAART. Closely monitor patients for treatment-associated toxicities, especially hepatic decompensation. [34878] Ribociclib: (Major) Avoid coadministration of lopinavir with ribociclib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Ribociclib has been shown to prolong the QT interval in a concentration-dependent manner. [28341] [61816] [65157] [65170] (Major) Avoid coadministration of ribociclib with ritonavir due to the potential for significantly increased exposure to ribociclib. If coadministration cannot be avoided, reduce the dose of ribociclib to 400 mg once daily. If ritonavir is discontinued, resume the previous ribociclib dose after at least 5 half-lives of ritonavir. Ribociclib is a CYP3A4 substrate. ritonavir is a strong CYP3A4 inhibitor. Coadministration with a strong inhibitor increased the ribociclib AUC and Cmax by 3.2-fold and 1.7-fold, respectively, in healthy volunteers. [61816] Ribociclib; Letrozole: (Major) Avoid coadministration of lopinavir with ribociclib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Ribociclib has been shown to prolong the QT interval in a concentration-dependent manner. [28341] [61816] [65157] [65170] (Major) Avoid coadministration of ribociclib with ritonavir due to the potential for significantly increased exposure to ribociclib. If coadministration cannot be avoided, reduce the dose of ribociclib to 400 mg once daily. If ritonavir is discontinued, resume the previous ribociclib dose after at least 5 half-lives of ritonavir. Ribociclib is a CYP3A4 substrate. ritonavir is a strong CYP3A4 inhibitor. Coadministration with a strong inhibitor increased the ribociclib AUC and Cmax by 3.2-fold and 1.7-fold, respectively, in healthy volunteers. [61816] Rifabutin: (Major) Coadministration of ritonavir and rifabutin results in clinically significant alterations of rifabutin pharmacokinetic parameters, with the rifabutin AUC being increased by 430%. In patients receiving any dosage of ritonavir, the dose of rifabutin should always be decreased to 150 mg every day or 300 mg three times per week. [46638] (Major) If lopinavir and rifabutin are administered concurrently, the manufacturer recommends a rifabutin dose reduction of at least 75% of the usual dose (i.e., a maximum dose of 150 mg every other day or 3 times per week). In addition, increase monitoring for adverse reactions is recommended. Use of these drugs together increases the AUC of rifabutin and it's metabolites. [28341] [46638] Rifampin: (Severe) Coadministration of rifampin and ritonavir results in markedly decreased ritonavir concentrations; HIV treatment failure and virologic resistance would be expected. Rifampin (300 or 600 mg daily for 10 days) decreases the AUC and Cmax of ritonavir (500 mg every 12 hours for 20 days) by 35% and 25%, respectively. Coadministration may lead to loss of virologic response if ritonavir is the sole protease inhibitor and increase the risk of hepatotoxicity. The DHHS/NIH HIV Treatment Guidelines recommend ritonavir and rifampin should not be coadministered and suggest the consideration of alternative antimycobacterial agents, such as rifabutin. However, CDC guidelines suggest no change in ritonavir or rifampin dose when the drugs are coadministered, but this appears to only be in the setting of low-dose ritonavir (i.e., 100 mg or 200 mg twice daily) used to 'boost' concentrations of other protease inhibitors. In this setting it would be less likely to produce adverse events than higher ritonavir doses; however, a net CYP3A4 induction still results when used with rifampin. [1299] [30314] [46638] (Severe) The coadministration of lopinavir and rifampin is contraindicated. Concurrent use may lead to loss of virologic response and possible resistance to lopinavir, the class of protease inhibitors, or other antiretroviral agents. [28341] [30314] [46638] Rifapentine: (Major) Rifapentine is an inducer of CYP3A4 and CYP2C8/9, and should not be coadministered with protease inhibitors as complex interactions may lead to decreased plasma concentrations of the anti-retroviral agents. In one study, indinavir Cmax and AUC were reduced by 55% and 70%, respectively. The clearance of indinavir was increased 3-fold in the presence of rifapentine while half-life did not change. Additionally, HIV patients treated with rifapentine have a higher rate of TB relapse than those treated with other rifamycin-based regimens; an alternative agent is recommended. [28483] [32432] [46638] Rifaximin: (Moderate) Although the clinical significance of this interaction is unknown, concurrent use of rifaximin and lopinavir may increase the systemic exposure to rifaximin; caution is advised if these drugs must be administered together. Rifaximin is a substrate for the drug transporter organic anion transporting polypeptide (OATP); lopinavir is an inhibitor of OATP1B1. In patients with hepatic impairment, the effects of reduced metabolism and transporter inhibition may further increase exposure to rifaximin. [28341] [29289] [56579] [61511] [61513] (Moderate) Although the clinical significance of this interaction is unknown, concurrent use of rifaximin, a P-glycoprotein (P-gp) substrate, and ritonavir, a P-gp inhibitor, may substantially increase the systemic exposure to rifaximin; caution is advised if these drugs must be administered together. During one in vitro study, coadministration with cyclosporine, a potent P-gp inhibitor, resulted in an 83-fold and 124-fold increase in the mean Cmax and AUC of rifaximin, respectively. In patients with hepatic impairment, the effects of reduced metabolism and P-gp inhibition may further increase exposure to rifaximin. [28341] [28380] [29289] [56579] Rilpivirine: (Major) Avoid coadministration of lopinavir with rilpivirine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Supratherapeutic doses of rilpivirine (75 to 300 mg/day) have caused QT prolongation. [28341] [44376] [65157] [65170] Riluzole: (Moderate) Coadministration of riluzole with ritonavir may result in decreased riluzole efficacy. In vitro findings suggest decreased riluzole exposure is likely. Riluzole is a CYP1A2 substrate and ritonavir is a CYP1A2 inducer. [29747] [47165] Rimegepant: (Major) Avoid coadministration of rimegepant with ritonavir; concurrent use may significantly increase rimegepant exposure. Rimegepant is a CYP3A4 and P-gp substrate; ritonavir is a strong CYP3A4 inhibitor and P-gp inhibitor. Coadministration of rimegepant with another strong CYP3A4 inhibitor increased rimegepant exposure by 4-fold. [28380] [34557] [47165] [65052] Riociguat: (Major) Concomitant use of riociguat with strong cytochrome CYP inhibitors and P-glycoprotein (P-gp)/breast cancer resistance protein (BCRP) inhibitors, such as ritonavir, increases riociguat exposure and may result in hypotension. Consider a starting adult dose of 0.5 mg PO three times a day when initiating riociguat in patients receiving strong CYP and P-gp/BCRP inhibitors. Monitor for signs and symptoms of hypotension on initiation and on treatment with strong CYP and P-gp/BCRP inhibitors. A dose reduction should be considered in patients who may not tolerate the hypotensive effect of riociguat. [56096] Ripretinib: (Moderate) Monitor patients more frequently for ripretinib-related adverse reactions if coadministered with ritonavir. Coadministration may increase the exposure of ripretinib and its active metabolite (DP-5439), which may increase the risk of adverse reactions. Ripretinib and DP-5439 are metabolized by CYP3A4 and ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased ripretinib and DP-5439 exposure by 99%. [47165] [65431] Risperidone: (Major) Avoid coadministration of lopinavir with risperidone due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Risperidone has been associated with a possible risk for QT prolongation and/or torsade de pointes (TdP), primarily in the overdose setting. [28225] [28341] [28414] [65157] [65170] (Moderate) Ritonavir may increase risperidone exposure; use together with caution and monitor for adverse effects of risperidone, including QT prolongation or other risperidone side effects. A decreased dosage of risperidone may be required. Risperidone is primarily metabolized by CYP2D6 and is also partially metabolized by CYP3A4; ritonavir inhibits both CYP2D6 and CYP3A4. [22256] [28414] [47165] [59321] [63411] Rivaroxaban: (Major) Avoid concomitant administration of rivaroxaban and ritonavir; significant increases in rivaroxaban exposure may increase bleeding risk. Rivaroxaban is a substrate of CYP3A4/5 and the P-glycoprotein (P-gp) transporter. Concurrent use of a single dose of rivaroxaban and ritonavir, a combined P-gp and strong CYP3A4 inhibitor, led to an increase in the rivaroxaban AUC by 150% and Cmax by 60%. Similar increases in pharmacodynamic effects such as factor Xa inhibition and PT prolongation were also observed. [28315] [44854] [47165] Rocuronium: (Moderate) Monitor clinical effect and decrease the rocuronium dosage, if needed, if rocuronium is used concomitantly with ritonavir. Ritonavir may potentially decrease biliary excretion of rocuronium. [47165] [65210] Roflumilast: (Major) Patients receiving roflumilast may have altered serum concentrations if coadministered with ritonavir. Ritonavir is a potent inhibitor and an inducer of CYP3A4, and roflumilast is a CYP3A4 substrate. Specific pharmacokinetic study of this potential interaction has not been conducted. [11416] [43551] [5044] [5110] Romidepsin: (Major) Avoid coadministration of lopinavir with romidepsin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Romidepsin has also been reported to prolong the QT interval. [28341] [37292] [65157] [65170] (Moderate) Monitor for toxicity related to increased romidepsin exposure and follow the dose modifications for toxicity during initial administration of romidepsin with ritonavir. Romidepsin is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. In a pharmacokinetic drug interaction trial a strong CYP3A4 inhibitor increased romidepsin AUC by approximately 25%. [37292] [47165] Rosuvastatin: (Major) Initiate rosuvastatin at a reduced dosage of 5 mg once daily if coadministered with lopinavir; do not exceed a rosuvastatin dosage of 10 mg once daily. When rosuvastatin was coadministered with lopinavir in healthy volunteers, the Cmax and AUC of rosuvastatin was increased 5-fold and 2-fold, respectively. Rosuvastatin is a substrate of the drug transporter organic anion transporting polypeptide (OATP1B1); lopinavir is OATP1B1 inhibitor. Closely monitor for statin-associated adverse reactions, such as myopathy and rhabdomyolysis. [27988] [28341] [56579] [61510] [61511] [61513] Ruxolitinib: (Major) Reduce the ruxolitinib dosage during coadministration with ritonavir in patients with myelofibrosis (MF) or polycythemia vera (PV) as increased ruxolitinib exposure and toxicity may occur; no dose adjustments are necessary for patients with graft-versus-host disease. In MF patients, reduce the initial dose to 10 mg PO twice daily for platelet count of 100,000 cells/mm3 or more and 5 mg PO once daily for platelet count of 50,000 to 99,999 cells/mm3. In PV patients, reduce the initial dose to 5 mg PO twice daily. Avoid the use of ritonavir in MF or PV patients who are stable on a ruxolitinib dose of 5 mg PO once daily. In MF or PV patients stable on ruxolitinib dose of 10 mg PO twice daily or more, reduce dose by 50%; in patients stable on ruxolitinib dose of 5 mg PO twice daily, reduce ruxolitinib to 5 mg PO once daily. Additional dose modifications should be made with frequent monitoring of safety and efficacy. Ruxolitinib is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. [46782] [47165] Sacituzumab Govitecan: (Major) Avoid coadministration of sacituzumab govitecan and ritonavir due to the risk of decreased sacituzumab govitecan exposure which may reduce its efficacy. The cytotoxic component of sacituzumab govitecan, SN-38, is metabolized by UGT1A1 and ritonavir is a UGT1A1 inducer. Formal drug interaction studies with sacituzumab govitecan have not been conducted but the concomitant use of UGT1A1 inducers is expected to decrease SN-38 exposure. [47165] [65328] Sacubitril; Valsartan: (Moderate) Concurrent use of lopinavir with valsartan may result in elevated valsartan serum concentrations. Valsartan is a substrate for the drug transporter organic anion transporting polypeptide (OATP1B1/1B3); lopinavir is an OATP1B1 inhibitor. Monitor for increased toxicities if these drugs are given together. [56579] [61510] [61511] [61513] (Minor) Valsartan is a substrate of the hepatic efflux transporter MRP2 and ritonavir is an inhibitor of MRP2. Coadministration may increase systemic exposure to valsartan. Patients should be monitored for adverse effects of valsartan during coadministration. [28315] [29130] [36646] [39870] [60860] Salmeterol: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] (Major) Avoid coadministration of salmeterol with ritonavir. The coadministration of salmeterol with CYP3A4 inhibitors can result in elevated salmeterol plasma concentrations and increased risk for adverse reactions, particularly cardiovascular effects. [28315] [28467] [47165] Sapropterin: (Moderate) Caution is advised with the concomitant use of sapropterin and ritonavir as coadministration may result in increased systemic exposure of ritonavir. Ritonavir is a substrate for the drug transporter P-glycoprotein (P-gp); in vitro data show that sapropterin may inhibit P-gp. If these drugs are used together, closely monitor for increased side effects of ritonavir. [28315] [33635] Saquinavir: (Major) Avoid coadministration of lopinavir; ritonavir with saquinavir due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. When coadministered with lopinavir; ritonavir 400/100 mg twice daily, the saquinavir dose is 1,000 mg twice daily. Lopinavir; ritonavir is associated with QT prolongation. Saquinavir boosted with ritonavir increases the QT interval in a dose-dependent fashion, which may increase the risk for serious arrhythmias such as torsade de pointes (TdP). [28341] [28995] [65157] [65170] Saxagliptin: (Major) The metabolism of saxagliptin is primarily mediated by CYP3A4/5. The saxagliptin dose is limited to 2.5 mg once daily when coadministered with a strong CYP3A4/5 inhibitor such as ritonavir. New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have also been reported with use of anti-retroviral protease inhibitors, such as ritonavir. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [36111] [7238] [7335] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients, including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [28341] [30575] [36111] Secobarbital: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] Segesterone Acetate; Ethinyl Estradiol: (Major) Coadministration may result in an increased or decreased effect of segesterone. Contraceptive efficacy may be reduced. Segesterone is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor and CYP3A4 inducer. [47165] [63429] (Major) Ritonavir increases the metabolism of oral contraceptives and non-oral combination contraceptives; coadministration decreases ethinyl estradiol AUC by 40% and Cmax by 32%. Women receiving hormonal contraceptives and anti-retroviral protease inhibitors (PIs), such as ritonavir, should be instructed to report any breakthrough bleeding or other adverse effects to their prescribers. It may be prudent for women who receive hormonal contraceptives concurrently with PIs to use an additional method of contraception to protect against unwanted pregnancy. Additionally, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive hormonal contraceptives concurrently with PIs should use an additional barrier method of contraception such as condoms. [46638] [5044] Selexipag: (Moderate) Concurrent use of lopinavir with selexipag may result in elevated selexipag serum concentrations. Selexipag is a substrate for the drug transporter organic anion transporting polypeptide (OATP1B1/1B3); lopinavir is an OATP1B1 inhibitor. Monitor for increased toxicities if these drugs are given together. [60472] [61510] [61511] [61513] Selpercatinib: (Major) Avoid coadministration of lopinavir; ritonavir with selpercatinib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir; ritonavir is associated with QT prolongation. Concentration-dependent QT prolongation has been observed with selpercatinib therapy. [28341] [65157] [65170] [65387] (Major) Avoid coadministration of selpercatinib and ritonavir due to the risk of increased selpercatinib exposure which may increase the risk of adverse reactions, including QT prolongation. If coadministration is unavoidable, reduce the dose of selpercatinib to 40 mg PO twice daily if original dose was 120 mg twice daily, and to 80 mg PO twice daily if original dose was 160 mg twice daily. Monitor ECGs for QT prolongation more frequently. If ritonavir is discontinued, resume the original selpercatinib dose after 3 to 5 elimination half-lives of ritonavir. Selpercatinib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased selpercatinib exposure by 133%. [47165] [65387] Selumetinib: (Major) Avoid coadministration of selumetinib and ritonavir due to the risk of increased selumetinib exposure which may increase the risk of adverse reactions. If coadministration is unavoidable, reduce the dose of selumetinib to 20 mg/m2 PO twice daily if original dose was 25 mg/m2 twice daily and 15 mg/m2 PO twice daily if original dose was 20 mg/m2 twice daily. If ritonavir is discontinued, resume the original selumetinib dose after 3 elimination half-lives of ritonavir. Selumetinib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased selumetinib exposure by 49%. [47165] [65246] Sertraline: (Major) Avoid coadministration of lopinavir with sertraline due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. The risk of sertraline-induced QT prolongation is generally considered to be low in clinical practice. Its effect on QTc interval is minimal (typically less than 5 msec), and the drug has been used safely in patients with cardiac disease (e.g., recent myocardial infarction, unstable angina, chronic heart failure). [28341] [28343] [64391] [64392] [64394] [64395] [64396] [65157] [65170] Short-acting beta-agonists: (Major) Avoid coadministration of lopinavir with short-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28341] [33925] [65157] [65170] Sibutramine: (Moderate) Due to ritonavir's potential inhibitory effects on various hepatic isoenzymes, close monitoring of serum drug concentrations and/or therapeutic and adverse effects is required when sibutramine is coadministered with ritonavir; dosage reduction may be needed. [4718] Sildenafil: (Major) Coadministration of ritonavir is contraindicated in patients receiving sildenafil for pulmonary arterial hypertension (PAH). If used for erectile dysfunction, the dose of sildenafil should not exceed 25 mg in 48 hours with increased monitoring for adverse reactions during times of coadministration. Concurrent use substantially increases the sildenafil plasma concentrations and may result in increased associated adverse events including hypotension, syncope, visual changes, and prolonged erection. Ritonavir, a strong CYP3A4 inhibitor, increased the AUC of sildenafil, a sensitive CYP3A4 substrate, by 11-fold in a drug interaction study. [2548] [28315] [46638] Silodosin: (Severe) Concurrent use of silodosin and ritonavir is contraindicated. Silodosin is extensively metabolized by CYP3A4; ritonavir is a potent inhibitor of this enzyme. Also of note, silodosin is a P-glycoprotein (P-gp) substrate and ritonavir is a P-gp inhibitor. Coadministration may cause significant increases in silodosin plasma concentrations, potentially resulting in adverse events. [34483] Simeprevir: (Major) Avoid concurrent use of simeprevir and lopinavir. Inhibition of the organic anion transporting polypeptide (OATP1B1) by lopinavir may increase the plasma concentrations of simeprevir, resulting in adverse effects. [28341] [28380] [56471] [56579] [61510] [61511] [61513] (Major) Avoid concurrent use of simeprevir and ritonavir. Inhibition of CYP3A4 and P-glycoprotein (P-gp) by ritonavir causes significantly increased plasma concentrations of simeprevir, potentially resulting in adverse effects. [28380] [47165] [56471] [56579] Simvastatin: (Severe) The coadministration of anti-retroviral protease inhibitors with simvastatin is contraindicated. Taking these drugs together may significantly increase the serum concentration of simvastatin; thereby increasing the risk of myopathy and rhabdomyolysis. One report has demonstrated that ritonavir plus saquinavir therapy markedly increases the AUC for simvastatin by 3059%. Simvastatin is a substrate for CYP3A4 and the drug transporter organic anion transporting polypeptide (OATP1B1); protease inhibitors are CYP3A4 and OATP inhibitors. [28605] [39682] [46638] [61510] [61511] [61512] [61513] Simvastatin; Sitagliptin: (Severe) The coadministration of anti-retroviral protease inhibitors with simvastatin is contraindicated. Taking these drugs together may significantly increase the serum concentration of simvastatin; thereby increasing the risk of myopathy and rhabdomyolysis. One report has demonstrated that ritonavir plus saquinavir therapy markedly increases the AUC for simvastatin by 3059%. Simvastatin is a substrate for CYP3A4 and the drug transporter organic anion transporting polypeptide (OATP1B1); protease inhibitors are CYP3A4 and OATP inhibitors. [28605] [39682] [46638] [61510] [61511] [61512] [61513] (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic agents should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30575] Siponimod: (Major) Avoid coadministration of lopinavir with siponimod due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Consult a cardiologist. Siponimod therapy prolonged the QT interval at recommended doses in a clinical study. Lopinavir is associated with QT prolongation. [28341] [64031] [65157] [65170] (Moderate) Concomitant use of siponimod and ritonavir may increase siponimod exposure. If the patient is also receiving a drug regimen containing a moderate CYP2C9 inhibitor, use of siponimod is not recommended due to a significant increase in siponimod exposure. Siponimod is a CYP2C9 and CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Coadministration with a moderate CYP2C9/CYP3A4 dual inhibitor led to a 2-fold increase in the exposure of siponimod. [47165] [64031] Sirolimus: (Major) Avoid the use of sirolimus with potent CYP3A4 inhibitors, such as protease inhibitors. Protease inhibitors may affect absorption and elimination of sirolimus leading to increased blood concentrations. Sirolimus is extensively metabolized by CYP3A4 in the gut and liver and undergoes counter-transport from enterocytes of the small intestine into the gut lumen by the P-glycoprotein drug efflux pump. Sirolimus is potentially recycled between enterocytes and the gut lumen to allow continued metabolism by CYP3A4. [28610] [28995] [47165] Sitagliptin: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic agents should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [30575] Sodium Bicarbonate: (Moderate) Concurrent administration of tipranavir and ritonavir with antacids results in decreased tipranavir concentrations. Administer tipranavir and ritonavir 2 hours before or 1 hour after antacids. [1800] [1802] Sodium Oxybate: (Major) One case report describes a possible interaction between sodium oxybate and ritonavir and saquinavir, leading to repetitive, clonic contractions. The patient also experienced shallow respirations, a heart rate of 40 beats per min, and was responsive only to painful stimuli. The exact contribution of ritonavir and saquinavir to this reaction cannot be determined since several other compounds were detected through a urinary toxin screen. [2546] Sofosbuvir; Velpatasvir; Voxilaprevir: (Major) Avoid concurrent administration of voxilaprevir and lopinavir. Taking these medications together may increase voxilaprevir plasma concentrations, potentially increasing the risk for adverse events. Voxilaprevir is a substrate for the drug transporter Organic Anion Transporting Polypeptides 1B1 (OATP1B1). Lopinavir is an OATP1B1 inhibitor. [61510] [61511] [61513] [62131] Solifenacin: (Major) Avoid coadministration of lopinavir with solifenacin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Solifenacin has been associated with dose-dependent prolongation of the QT interval. Torsade de pointes (TdP) has been reported with postmarketing use, although causality was not determined. [28341] [30515] [65157] [65170] (Major) Use of ritonavir with solifenacin may increase exposure to solifenacin and risk for solifenacin-related side effects. If these drugs must be administered together, do not exceed solifenacin 5 mg per day in adults; do not exceed the initial solifenacin starting dose in pediatric patients. Ritonavir is a potent CYP3A4 inhibitor and solifenacin is a CYP3A4 substrate. Coadministration of another strong CYP3A4 inhibitor increased solifenacin exposure by 2.7-fold. [47165] [54021] [65485] Sonidegib: (Major) Avoid the concomitant use of sonidegib and ritonavir as sonidegib levels may be significantly increased resulting in an increased risk of adverse events, particularly musculoskeletal toxicity. Sonidegib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor increased the mean Cmax and AUC of sonidegib by 2.2-fold and 1.5-fold, respectively [28315] [58864] [60000] [60002] Sorafenib: (Major) Avoid coadministration of sorafenib with Lopinavir due to the risk of additive QT prolongation. If concomitant use is unavoidable, monitor electrocardiograms and correct electrolyte abnormalities. An interruption or discontinuation of sorafenib therapy may be necessary if QT prolongation occurs. Both drugs are associated with QTc prolongation. [28341] [31832] [65157] [65170] Sotalol: (Major) Avoid coadministration of lopinavir with sotalol due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Sotalol administration is associated with QT prolongation and torsade de pointes (TdP). Proarrhythmic events should be anticipated after initiation of therapy and after each upward dosage adjustment. [28234] [28341] [65157] [65170] (Major) The use of ritonavir could result in QT prolongation. Drugs with a possible risk for QT prolongation and TdP that should be used cautiously and with close monitoring with ritonavir include sotalol. [28234] [47165] St. John's Wort, Hypericum perforatum: (Severe) Use of St. John's wort with protease inhibitors is contraindicated. St. John's wort is an inducer of CYP3A and is expected to significantly decrease the plasma concentrations of all currently marketed protease inhibitors. Reductions in plasma concentrations of these drugs could lead to HIV treatment failures or the development of viral-resistance. St. John's wort in all forms, including teas, should be avoided in HIV patients treated with these agents. [2718] [28315] [28731] [28995] [46638] [4718] [4865] [4935] [8102] Sufentanil: (Moderate) Because the dose of the sufentanil sublingual tablets cannot be titrated, consider an alternate opiate if a protease inhibitor must be administered. Consider a reduced dose of sufentanil injection with frequent monitoring for respiratory depression and sedation if concurrent use of a protease inhibitor is necessary. If a protease inhibitor is discontinued, consider increasing the sufentanil injection dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Sufentanil is a CYP3A4 substrate, and coadministration with a strong CYP3A4 inhibitor like protease inhibitors can increase sufentanil exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of sufentanil. If a protease inhibitor is discontinued, sufentanil plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to sufentanil. [30966] [47165] [63731] Sulfonylureas: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. A possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic agents should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. [28380] [29012] [30575] [31320] [34471] [34472] [34489] [34490] [34491] [34557] [47165] [51227] [58000] [58763] Sunitinib: (Major) Avoid coadministration of lopinavir with sunitinib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs are associated with QT prolongation. [28341] [31970] [65157] [65170] (Major) Avoid coadministration of ritonavir with sunitinib if possible due to increased sunitinib exposure, which may increase the risk of QT prolongation. If concomitant use is unavoidable, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Consider reducing the daily dose of sunitinib to a minimum of 37.5 mg for patients with GIST or RCC, and to a minimum of 25 mg for patients with pNET. Sunitinib is a CYP3A4 substrate that can cause QT prolongation. Ritonavir is a strong CYP3A4 inhibitor that also causes QT prolongation. Coadministration with another strong CYP3A4 inhibitor increased exposure to sunitinib and its primary active metabolite by 51%. [31970] [47165] Suvorexant: (Major) Coadministration of suvorexant and ritonavir is not recommended due to the potential for significantly increased suvorexant exposure. Suvorexant is a CYP3A4 substrate. Ritonavir is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased the suvorexant AUC by 2.8-fold. [57780] Tacrolimus: (Major) Avoid coadministration of lopinavir with tacrolimus due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Tacrolimus may prolong the QT interval and cause torsade de pointes (TdP). [28341] [28611] [55401] [60497] [65157] [65170] (Major) Closely monitor tacrolimus concentrations and adjust the dose of tacrolimus as appropriate if coadministration with ritonavir is necessary. Concurrent administration is expected to increase tacrolimus whole blood trough concentrations and increase the risk of serious adverse reactions including nephrotoxicity, neurotoxicity, and QT prolongation. Consider a tacrolimus dose reduction to 0.5 mg to 1 mg once per week when coadministered with a protease inhibitor. In one study, the tacrolimus half-life increased to 10.6 days in one patient and 20.6 days in another following coadministration of tacrolimus and lopinavir; ritonavir. Up to 80% reductions in tacrolimus dosages and 7-fold increase in dosage intervals were needed when tacrolimus was coadministered with protease inhibitors in studies. Tacrolimus is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. [28611] [47165] [65478] [65480] [65483] Tadalafil: (Major) For the treatment of erectile dysfunction, do not exceed 10 mg of tadalafil within 72 hours of ritonavir for the 'as needed' dose or 2.5 mg daily for the 'once-daily' dose. Avoid the use of tadalafil for pulmonary hypertension during the initiation of ritonavir therapy. Stop tadalafil at least 24 hours prior to starting ritonavir. After at least 1 week of ritonavir therapy, resume tadalafil at 20 mg once daily. Increase to 40 mg once daily based on tolerability. Coadministration of ritonavir with tadalafil results in a 124% increase in tadalafil AUC. Substantially increased tadalafil plasma concentrations may result in increased adverse events including hypotension, syncope, visual changes, and prolonged erection. It should be noted that during once daily administration of tadalafil, the presence of continuous plasma tadalafil concentrations may change the potential for interactions with potent inhibitors of CYP3A4. [28220] [28315] [40259] Talazoparib: (Moderate) Monitor for an increase in talazoparib-related adverse reactions if coadministration with ritonavir is necessary. Talazoparib is a P-glycoprotein (P-gp) substrate and ritonavir is a P-gp inhibitor. Coadministration with other P-gp inhibitors increased talazoparib exposure by 8% to 45%. [28380] [34557] [63651] Tamoxifen: (Major) Avoid coadministration of lopinavir with tamoxifen due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Tamoxifen has been reported to prolong the QT interval, usually in overdose or when used in high doses. Rare case reports of QT prolongation have also been described when tamoxifen is used at lower doses. [28341] [61870] [61871] [61872] [63589] [65157] [65170] Tamsulosin: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. [29677] [4194] [8102] Tasimelteon: (Major) Concurrent use of tasimelteon and strong inhibitors of CYP3A4, such as ritonavir, should be avoided if possible. Because tasimelteon is partially metabolized via CYP3A4, a large increase in exposure of tasimelteon with the potential for adverse reactions is possible if these drugs are coadministered. During administration of tasimelteon and another potent CYP3A4 inhibitor, tasimelteon exposure increased by about 50%. [56665] Tazemetostat: (Major) Avoid coadministration of tazemetostat with ritonavir as concurrent use may increase tazemetostat exposure and the frequency and severity of adverse reactions. Tazemetostat is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Coadministration of a moderate CYP3A4 inhibitor increased tazemetostat exposure by 3.1-fold. [47165] [64952] Telaprevir: (Major) Concurrent administration of lopinavir; ritonavir with telaprevir is not recommended. If lopinavir; ritonavir and telaprevir are coadministered, monitor the patient closely for HIV and hepatitis C treatment failures. [44393] [5070] Telavancin: (Major) Avoid coadministration of lopinavir with telavancin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs have been associated with QT prolongation. [28341] [36615] [65157] [65170] Telithromycin: (Major) Avoid coadministration of lopinavir with telithromycin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Telithromycin is associated with QT prolongation and torsade de pointes (TdP). [28156] [28341] [65157] [65170] (Major) Avoid coadministration of telithromycin and ritonavir due to increased telithromycin exposure which may increase the risk of QT prolongation; ritonavir exposure may also increase. Both drugs are substrates and strong inhibitors of CYP3A4. [28156] [47165] Telotristat Ethyl: (Moderate) Use caution if coadministration of telotristat ethyl and lopinavir is necessary, as the systemic exposure of lopinavir may be decreased resulting in reduced efficacy and viral resistance; exposure to telotristat ethyl may also be increased. If these drugs are used together, monitor patients for suboptimal efficacy of lopinavir as well as an increase in adverse reactions related to telotristat ethyl. Lopinavir is a CYP3A4 substrate. The mean Cmax and AUC of another sensitive CYP3A4 substrate was decreased by 25% and 48%, respectively, when administered with telotristat ethyl; the mechanism of this interaction appears to be that telotristat ethyl increases the glucuronidation of the CYP3A4 substrate. [28341] [56579] [61795] (Moderate) Use caution if coadministration of telotristat ethyl and ritonavir is necessary, as the systemic exposure of ritonavir may be decreased resulting in reduced efficacy; exposure to telotristat ethyl may also be increased. If these drugs are used together, monitor patients for suboptimal efficacy of ritonavir as well as an increase in adverse reactions related to telotristat ethyl. Ritonavir is a CYP3A4 substrate. The mean Cmax and AUC of another sensitive CYP3A4 substrate was decreased by 25% and 48%, respectively, when coadministered with telotristat ethyl; the mechanism of this interaction appears to be that telotristat ethyl increases the glucuronidation of the CYP3A4 substrate. Coadministration with a strong CYP3A4 inducer decreased the ritonavir AUC and Cmax by 35% and 25%, respectively. Additionally, the active metabolite of telotristat ethyl, telotristat, is a substrate of P-glycoprotein (P-gp) and ritonavir is a P-gp inhibitor. Exposure to telotristat ethyl may increase. [28380] [34557] [61795] Temsirolimus: (Major) Avoid coadministration of ritonavir with temsirolimus due to increased plasma concentrations of the primary active metabolite of temsirolimus (sirolimus); exposure to ritonavir may also increase. If concomitant use is unavoidable, consider reducing the dose of temsirolimus to 12.5 mg per week. Allow a washout period of approximately 1 week after discontinuation of ritonavir before increasing temsirolimus to its original dose. Temsirolimus is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor did not significantly affect temsirolimus exposure, but increased the AUC and Cmax of sirolimus by 3.1-fold and 2.2-fold, respectively. Ritonavir is also a P-glycoprotein (P-gp) substrate and temsirolimus is a P-gp inhibitor. Concomitant use may lead to increased concentrations of ritonavir. [34557] [47165] [50586] Teniposide: (Moderate) Concurrent administration of teniposide with ritonavir may result in elevated teniposide plasma concentrations. Teniposide is a substrate for CYP3A4 and P-glycoprotein (P-gp); ritonavir inhibits both CYP3A44 and P-gp. Caution and close monitoring are advised if these drugs are administered together. [28498] [34660] [47165] [48961] [58664] Tenofovir Alafenamide: (Moderate) Concurrent use of lopinavir with tenofovir alafenamide may result in elevated tenofovir serum concentrations. Tenofovir alafenamide is a substrate for the drug transporter organic anion transporting polypeptide (OATP1B1/1B3); lopinavir is an OATP1B1 inhibitor. When 10 mg of tenofovir alafenamide was administered daily with lopinavir; ritonavir (800 mg/200 mg PO daily), the tenofovir Cmax and AUC increased by 2.19-fold and 1.47-fold, respectively. Monitor for increased toxicities if these drugs are given together. [60269] [61510] [61511] [61513] Tenofovir Alafenamide: (Moderate) Concurrent use of lopinavir with tenofovir alafenamide may result in elevated tenofovir serum concentrations. Tenofovir alafenamide is a substrate for the drug transporter organic anion transporting polypeptide (OATP1B1/1B3); lopinavir is an OATP1B1 inhibitor. When 10 mg of tenofovir alafenamide was administered daily with lopinavir; ritonavir (800 mg/200 mg PO daily), the tenofovir Cmax and AUC increased by 2.19-fold and 1.47-fold, respectively. Monitor for increased toxicities if these drugs are given together. [60269] [61510] [61511] [61513] Tenofovir, PMPA: (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrate, concurrently with inhibitors of P-gp and BCRP, such as ritonavir. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. [28193] [58664] (Minor) There are varying results in reports of an interaction between tenofovir and lopinavir; ritonavir. In one report, the concurrent administration of tenofovir with lopinavir; ritonavir increased tenofovir Cmax 31%, AUC 34%, and Cmin 29%, with slight (15%) decreases in lopinavir Cmax and AUC; the alterations may be a food effect rather than a drug-drug interaction. In another report, lopinavir; ritonavir (400 mg; 100 mg PO twice daily for 14 days) increased the tenofovir (300 mg/day PO) Cmin 51% and AUC 32%, with no effect seen on lopinavir; ritonavir pharmacokinetics. While the clinical significance of this interaction is unknown, and is suspected to be insignificant, patients receiving lopinavir; ritonavir with tenofovir should be monitored for tenofovir-associated adverse events. [46638] Terbinafine: (Moderate) Caution is advised when administering terbinafine with ritonavir. Although this interaction has not been studied by the manufacturer, and published literature suggests the potential for interactions to be low, taking these drugs together may alter the systemic exposure of terbinafine. Predictions about the interaction can be made based on the metabolic pathways of both drugs. Terbinafine is metabolized by at least 7 CYP isoenyzmes, with major contributions coming from CYP1A2, CYP2C9, and CYP3A4; ritonavir is an inducer of CYP1A2 and CYP2C9, and an inhibitor/inducer of CYP3A4. Monitor patients for adverse reactions and breakthrough fungal infections if these drugs are coadministered. [37590] [43880] [43881] [47165] [56538] Terbutaline: (Major) Avoid coadministration of lopinavir with short-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28341] [33925] [65157] [65170] Terfenadine: (Severe) Caution should be used in patients receiving protease inhibitors concurrently with drugs metabolized via CYP3A4 and known to cause QT prolongation. Protease inhibitors inhibit the CYP3A4 isoenzyme at clinically relevant concentrations, which may lead to increased serum concentrations of terfenadine and an increased potential for QT prolongation or other adverse effects. Serious and/or life-threatening drug interactions could potentially occur between protease inhibitors and terfenadine. [141] [1800] [4865] [5044] Tesamorelin: (Minor) Use caution when coadministering tesamorelin with ritonavir as their concurrent use may alter ritonavir plasma concentrations. In a pharmacokinetic study, multiple 2 mg doses of tesamorelin administered with ritonavir resulted in a 9% decrease in ritonavir AUC and an 11% decrease in ritonavir Cmax. The clinical impact of these pharmacokinetic changes is unknown; however, patients should be monitored for decreased ritonavir efficacy. [42405] Testosterone: (Moderate) Concurrent administration of testosterone with ritonavir may result in elevated plasma concentrations of testosterone and ritonavir. Testosterone is a substrate of the hepatic isoenzyme CYP3A4 and the drug transporter P-glycoprotein (P-gp). Ritonavir is a CYP3A4 and P-gp inhibitor. In addition, testosterone inhibits P-gp; ritonavir is a substrate of P-gp. Caution and close monitoring are advised if these drugs are administered together. [11580] [11581] [28380] [56579] Tetrabenazine: (Major) Avoid coadministration of lopinavir with tetrabenazine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Tetrabenazine causes a small increase in the corrected QT interval (QTc). [28341] [34389] [65157] [65170] Tezacaftor; Ivacaftor: (Major) If ritonavir and ivacaftor are taken together, administer ivacaftor at the usual recommended dose but reduce the frequency to twice weekly. Ivacaftor is a CYP3A substrate and ritonavir is a CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased ivacaftor exposure by 8.5-fold. [48524] (Major) Reduce the dosing frequency of tezacaftor; ivacaftor when coadministered with ritonavir; coadministration may increase tezacaftor; ivacaftor exposure and adverse reactions. When combined, dose 1 tezacaftor; ivacaftor combination tablet twice a week, approximately 3 to 4 days apart (i.e., Day 1 and Day 4). The evening dose of ivacaftor should not be taken. Both tezacaftor and ivacaftor are CYP3A substrates (ivacaftor is a sensitive substrate); ritonavir is a strong CYP3A inhibitor. Coadministration of a strong CYP3A inhibitor increased tezacaftor and ivacaftor exposure 4- and 15.6-fold, respectively. [47165] [62870] Theophylline, Aminophylline: (Moderate) Ritonavir decreased theophylline AUC and Cmax by 43% and 52%, respectively, when the two drugs were coadministered. Higher dosages of aminophylline might be required. [1800] [5044] (Moderate) Ritonavir decreased theophylline AUC and Cmax by 43% and 52%, respectively, when the two drugs were coadministered. If these drugs are used together, therapeutic drug monitoring should be considered. Higher dosages of theophylline might be required. [47165] Thiazolidinediones: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients on antidiabetic agents should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated. In addition, coadministration of atazanavir with rosiglitazone may result in elevated rosiglitazone plasma concentrations. Rosiglitazone is a substrate for CYP2C8; atazanavir is a weak inhibitor of CYP2C8. [28142] [28172] [28380] [30575] [31320] [34557] [47165] [50768] [51227] Thiopental: (Major) Concurrent use of ritonavir with phenobarbital or other barbiturates should be done cautiously. Increased doses of anticonvulsants may be required due metabolism induction by ritonavir. However, since these anticonvulsants are hepatic enzyme inducing drugs, increased metabolism of protease inhibitors may occur, leading to decreased antiretroviral efficacy. Close monitoring of drug concentrations and/or therapeutic and adverse effects is required. [46638] (Moderate) Barbiturates may increase the metabolism of lopinavir and lead to decreased antiretroviral efficacy. In addition, coadministration of lopinavir boosted with ritonavir may induce the CYP metabolism of barbiturates, resulting in decreased barbiturate concentrations. Appropriate dose adjustments necessary to ensure optimum levels of both anti-retroviral agent and the barbiturate are unknown; however, once daily lopinavir; ritonavir should not be used. Anticonvulsant serum concentrations should be monitored closely if these agents are added; the patient should be observed for changes in the clinical efficacy of the antiretroviral or anticonvulsant regimen. [28341] [46638] Thioridazine: (Severe) Coadministration of lopinavir with thioridazine is contraindicated due to the potential for additive QT prolongation. Thioridazine is associated with a well-established risk of QT prolongation and torsade de pointes (TdP). Lopinavir is associated with QT prolongation. [28225] [28293] [28341] (Moderate) Close clinical monitoring is recommended during coadministration; thioridazine dose reductions may be required. The plasma concentrations of thioridazine may be elevated when administered concurrently with ritonavir. Elevated levels of thioridazine may result in prolongation of the QTc interval and may increase the risk of serious, potentially fatal, cardiac arrhythmias, such as torsades de pointes. [43069] [47165] Thiotepa: (Major) Avoid the concomitant use of thiotepa and ritonavir if possible; reduced metabolism to the active thiotepa metabolite may result in decreased thiotepa efficacy. Consider an alternative agent with no or minimal potential to inhibit CYP3A4. If coadministration is necessary, monitor patients for signs of reduced thiotepa efficacy. In vitro, thiotepa is metabolized via CYP3A4 to the active metabolite, TEPA; ritonavir is a strong CYP3A4 inhibitor. [47165] [61718] Tiagabine: (Moderate) Concurrent administration of tiagabine with ritonavir may result in elevated tiagabine plasma concentrations. Tiagabine is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [58664] [7573] Ticagrelor: (Major) Avoid the concomitant use of ticagrelor and ritonavir. Ticagrelor is a substrate of CYP3A4/5 and P-glycoprotein (P-gp), and ritonavir is a potent CYP3A4 inhibitor and a P-gp inhibitor. Concomitant use with ritonavir substantially increases ticagrelor exposure which may increase the bleeding risk. In addition, ticagrelor is also a mild CYP3A4 inhibitor and P-gp inhibitor. Ritonavir is a substrate of both CYP3A4 and P-gp. [44951] Timolol: (Moderate) Timolol is significantly metabolized by CYP2D6 isoenzymes. CYP2D6 inhibitors, such as ritonavir, may impair timolol metabolism; the clinical significance of such interactions is unknown. [5044] [5270] Tinidazole: (Major) Medications with significant alcohol content should not be ingested during therapy with tinidazole and should be avoided for 3 days after therapy is discontinued. Oral solutions of lopinavir; ritonavir contain ethanol. Administration of lopinavir; ritonavir oral solution to patients receiving or who have recently received tinidazole may result in disulfiram-like reactions. A disulfiram reaction would not be expected to occur with non-ethanol containing formulations of lopinavir; ritonavir (e.g., tablets). [28341] [48576] (Moderate) Coadministration of tinidazole with ritonavir may accelerate the elimination of tinidazole, decreasing the plasma concentration of tinidazole, or may prolong the half-life of tinidazole, increasing the plasma concentration of tinidazole. Tinidazole is a CYP3A4 substrate, and ritonavir is a CYP3A4 inhibitor and strong CYP3A4 inducer. Additionally, ritonavir oral solution and capsules contain ethanol. Medications with significant alcohol content should not be ingested during therapy with tinidazole and should be avoided for 3 days after therapy is discontinued. Administration of ritonavir oral solution and capsules to patients receiving or who have recently received tinidazole may result in disulfiram-like reactions. A disulfiram reaction would not be expected to occur with non-ethanol containing formulations of ritonavir (e.g., tablets or oral powder). [28315] [29931] [47165] Tiotropium; Olodaterol: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] (Moderate) Beta-agonists, such as olodaterol, may be associated with adverse cardiovascular effects including QT interval prolongation. Beta-agonists should be administered with extreme caution to patients being treated with drugs known to prolong the QT interval because the action of beta-agonists on the cardiovascular system may be potentiated. Drugs with a possible risk for QT prolongation and TdP that should be used cautiously and with close monitoring with olodaterol include ritonavir. [47165] [57710] Tofacitinib: (Major) A dosage reduction of tofacitinib is necessary if coadministered with ritonavir. In patients receiving 5 mg twice daily, reduce to 5 mg once daily; in patients receiving 10 mg twice daily, reduce to 5 mg twice daily; in patients receiving 22 mg once daily of the extended-release (XR) formulation, switch to 11 mg XR once daily; in patients receiving 11 mg XR once daily, switch to the immediate-release formulation at a dose of 5 mg once daily. Tofacitinib exposure is increased when coadministered with ritonavir. Ritonavir is a strong CYP3A4 inhibitor; tofacitinib is a CYP3A4 substrate. Coadministration with another strong CYP3A4 inhibitor increased tofacitinib exposure by 2-fold. [28315] [52315] [56579] Tolterodine: (Major) Avoid coadministration of lopinavir with tolterodine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Tolterodine has been associated with dose-dependent prolongation of the QT interval, especially in poor CYP2D6 metabolizers. [28341] [31112] [65157] [65170] (Major) Reduce the dose of immediate-release tolterodine to 1 mg twice daily and extended-release tolterodine to 2 mg once daily if coadministered with ritonavir. Concurrent use may increase tolterodine exposure. ritonavir is a strong CYP3A4 inhibitor. In CYP2D6 poor metabolizers, the CYP3A4 pathway becomes important in tolterodine elimination. Because it is difficult to assess which patients will be poor CYP2D6 metabolizers, reduced doses of tolterodine are advised when administered with strong CYP3A4 inhibitors. In a drug interaction study, coadministration of a strong CYP3A4 inhibitor increased the tolterodine AUC by 2.5-fold in CYP2D6 poor metabolizers. [31112] [43295] [47165] Tolvaptan: (Severe) The concomitant use of tolvaptan and ritonavir is contraindicated. Concurrent use is expected to increase tolvaptan exposure. Tolvaptan is a sensitive CYP3A4 substrate; ritonavir is a strong inhibitor of CYP3A4. Coadministration of another strong CYP3A4 inhibitor increased tolvaptan exposure 5-fold. No data exists regarding the appropriate dose adjustment needed to allow safe administration of tolvaptan with strong CYP3A4 inhibitors. [35780] [47165] [63106] Topiramate: (Moderate) Concurrent administration of topiramate with ritonavir may result in decreased concentrations of ritonavir. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Ritonavir is metabolized by this enzyme. Caution and close monitoring are advised if these drugs are administered together. [28378] [57036] [58664] Topotecan: (Major) Avoid coadministration of ritonavir with oral topotecan due to increased topotecan exposure; ritonavir may be administered with intravenous topotecan. Oral topotecan is a substrate of P-glycoprotein (P-gp) and ritonavir is a P-gp inhibitor. Oral administration within 4 hours of another P-gp inhibitor increased the dose-normalized AUC of topotecan lactone and total topotecan 2-fold to 3-fold compared to oral topotecan alone. [28380] [33536] [33578] [46322] Toremifene: (Major) Avoid coadministration of lopinavir; ritonavir with toremifene due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir; ritonavir is associated with QT prolongation. Toremifene has been shown to prolong the QTc interval in a dose- and concentration-related manner. [28341] [28822] [65157] [65170] (Major) Avoid coadministration of ritonavir with toremifene if possible due to increased plasma concentrations of toremifene which may result in QT prolongation. If concomitant use is unavoidable, closely monitor ECGs for QT prolongation and monitor electrolytes; correct hypokalemia or hypomagnesemia prior to administration of toremifene. Toremifene is a CYP3A4 substrate that has been shown to prolong the QTc interval in a dose- and concentration-related manner, and ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased toremifene exposure by 2.9-fold; exposure to N-demethyltoremifene was reduced by 20%. [28822] [47165] Trabectedin: (Major) Avoid the concomitant use of trabectedin with ritonavir due to the risk of increased trabectedin exposure. Trabectedin is a CYP3A substrate and ritonavir is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased the systemic exposure of a single dose of trabectedin (0.58 mg/m2 IV) by 66% compared to a single dose of trabectedin (1.3 mg/m2) given alone. [47165] [60248] Tramadol: (Major) Tramadol is primarily metabolized by CYP2D6 and CYP3A4; drugs that inhibit these enzymes, such as ritonavir, may decrease the metabolism of tramadol. This may result in a decreased concentration of the active metabolite (O-desmethyltramadol) leading to decreased analgesic effects and possibly increased side effects (seizures and serotonin syndrome) due to higher tramadol concentrations. [40255] [5043] [9316] Trandolapril; Verapamil: (Moderate) Concurrent administration of verapamil with ritonavir may result in elevated plasma concentrations of both drugs. Both verapamil and ritonavir are substrates and inhibitors of CYP3A4. Verapamil also inhibits the drug transporter P-glycoprotein (P-gp); ritonavir is a substrate of P-gp. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [11554] [40025] [5044] [56565] [6446] Trazodone: (Major) Avoid coadministration of lopinavir with trazodone due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Trazodone can prolong the QT/QTc interval at therapeutic doses. In addition, there are postmarketing reports of torsade de pointes (TdP). [28341] [38831] [65157] [65170] (Major) Avoid coadministration of trazodone with ritonavir due to the potential for increased trazodone exposure and associated adverse effects including QT prolongation. If concurrent use cannot be avoided, consider a reduced dose of trazodone based on tolerability. Trazodone is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Coadministration of other strong CYP3A4 inhibitors increased the exposure of trazodone compared to the use of trazodone alone. [28315] [38831] [46638] [47165] Triamcinolone: (Moderate) Ritonavir may inhibit the CYP3A4 metabolism of triamcinolone, resulting in increased plasma triamcinolone concentrations and reduced serum cortisol concentrations. There have been reports of clinically significant drug interactions in patients receiving ritonavir (a strong CYP3A4 inhibitor) along with corticosteroids resulting in systemic corticosteroid effects including, but not limited to, Cushing syndrome and adrenal suppression. Consider the benefit-risk of concomitant use and monitor for systemic corticosteroid side effects. Consider using an alternative treatment to triamcinolone, such as a corticosteroid not metabolized by CYP3A4 (i.e., beclomethasone or prednisolone). In some patients, a corticosteroid dose adjustment may be needed. If corticosteroid therapy is to be discontinued, consider tapering the dose over a period of time to decrease the potential for withdrawal. [28341] [47165] [56202] Triazolam: (Severe) Coadministration of triazolam, a primary CYP3A4 substrate, with strong CYP3A4 inhibitors, such as protease inhibitors, is contraindicated by the manufacturer of triazolam due to the risk for increased and prolonged sedation and respiratory depression. Concurrent use is expected to produce large increases in systemic exposure to triazolam, with the potential for serious adverse effects. [28142] [28341] [28731] [28839] [28995] [29012] [31320] [32432] [41543] [46638] [47165] Triclabendazole: (Major) Avoid coadministration of lopinavir with triclabendazole due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Transient prolongation of the mean QTc interval was noted on the ECG recordings in dogs administered triclabendazole. [28341] [63962] [65157] [65170] Tricyclic antidepressants: (Major) Avoid coadministration of lopinavir with tricyclic antidepressants (TCAs) due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. TCAs share pharmacologic properties similar to the Class IA antiarrhythmic agents and may prolong the QT interval, particularly in overdose or with higher-dose prescription therapy (elevated serum concentrations). [28225] [28341] [28415] [28416] [65157] [65170] (Moderate) A dose reduction of the tricyclic antidepressant (TCA) may be necessary when coadministered with ritonavir. Concurrent use may result in elevated TCA plasma concentrations. [47165] Trifluoperazine: (Major) Avoid coadministration of lopinavir with trifluoperazine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Trifluoperazine is associated with a possible risk for QT prolongation. [28341] [28415] [65157] [65170] Trimetrexate: (Moderate) Protease inhibitors inhibit the cytochrome P450 3A4 isoenzyme. Concurrent administration of trimetrexate with protease inhibitors may result in increased trimetrexate levels. Monitor patients closely. [4718] [5172] [5206] [5224] Trimipramine: (Moderate) A dose reduction of the tricyclic antidepressant (TCA) may be necessary when coadministered with ritonavir. Concurrent use may result in elevated TCA plasma concentrations. [47165] Triptorelin: (Major) Avoid coadministration of lopinavir with triptorelin due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Androgen deprivation therapy (i.e., triptorelin) may prolong the QT/QTc interval. [28341] [45411] [65157] [65170] Tucatinib: (Moderate) Monitor for increased toxicity of ritonavir if coadministered with tucatinib. Concurrent use may increase the plasma concentrations of ritonavir. Ritonavir is a CYP3A4 substrate and tucatinib is a strong CYP3A4 inhibitor. [47165] [65295] Ubrogepant: (Severe) Coadministration of ubrogepant and ritonavir is contraindicated as concurrent use may increase ubrogepant exposure and the risk of adverse effects. Ubrogepant is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor resulted in a 9.7-fold increase in the exposure of ubrogepant. [47165] [64874] Ulipristal: (Moderate) Use of ulipristal and ritonavir may increase the plasma concentration of ulipristal but is not likely to be significant for emergency contraceptive use. Avoid ritonavir if ulipristal is given chronically for hormonal conditions. Ulipristal is a substrate of CYP3A4 and ritonavir is a potent CYP3A4 inhibitor and in chronic use, may induce CYP3A4. Use together is likely to increase ulipristal concentrations overall, which may increase the risk for ulipristal-related adverse reactions. [41569] [50623] Umeclidinium; Vilanterol: (Major) Avoid coadministration of lopinavir with long-acting beta-agonists due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Beta-agonists may be associated with adverse cardiovascular effects including QT interval prolongation, usually at higher doses, when associated with hypokalemia, or when used with other drugs known to prolong the QT interval. This risk may be more clinically significant with long-acting beta-agonists as compared to short-acting beta-agonists. [28318] [28341] [32901] [33925] [41231] [65157] [65170] Upadacitinib: (Moderate) Use upadacitinib with caution in patients receiving chronic treatment with ritonavir as upadacitinib exposure and adverse effects may be increased. Upadacitinib is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Concurrent use of upadacitinib with a strong inhibitor increased upadacitinib exposure by 75%. [47165] [64572] Valbenazine: (Major) The dose of valbenazine should be reduced to 40 mg once daily during co-administration with a strong CYP3A4 inhibitor, such as ritonavir. QT prolongation is not clinically significant at valbenazine concentrations expected with recommended dosing; however, valbenazine concentrations may be higher in patients taking a strong CYP3A4 inhibitor and QT prolongation may become clinically significant. [61873] Valproic Acid, Divalproex Sodium: (Major) In a single case report, possible ritonavir-mediated induction of valproic acid glucuronidation resulted in a decrease in valproic acid concentrations and efficacy. A man with bipolar disorder and HIV was stabilized on valproic acid 250 mg PO three times daily. Treatment was started with lopinavir; ritonavir and lamivudine, 3TC; zidovudine, ZDV in addition to the valproic acid. Three weeks after starting the antiretroviral medication, his manic symptoms worsened. Upon hospital admission due to the mania, his valproic acid concentration had decreased 48% (from 495 to 238 micromol/l). His valproic acid dose was increased to 1500 mg and olanzapine was introduced. The valproic acid concentration following this dose escalation was 392 micromol/l, and the patient improved clinically. Of note, the patient had also received paroxetine for treatment of comorbid depression when the antiretrovirals were initiated, but the SSRI was discontinued by the patient after 5 days. The SSRI may have contributed to the initial hypomanic episode. Clinicians should be aware of this potential interaction and closely monitor valproic acid concentrations and efficacy. A valproic acid dose increase may be needed. In addition, valproic acid is an inducer of P-glycoprotein (P-gp) and an inhibitor/inducer of CYP3A4; ritonavir is a substrate of both CYP3A4 and P-gp. [57048] [57080] [8650] Valsartan: (Moderate) Concurrent use of lopinavir with valsartan may result in elevated valsartan serum concentrations. Valsartan is a substrate for the drug transporter organic anion transporting polypeptide (OATP1B1/1B3); lopinavir is an OATP1B1 inhibitor. Monitor for increased toxicities if these drugs are given together. [56579] [61510] [61511] [61513] (Minor) Valsartan is a substrate of the hepatic efflux transporter MRP2 and ritonavir is an inhibitor of MRP2. Coadministration may increase systemic exposure to valsartan. Patients should be monitored for adverse effects of valsartan during coadministration. [28315] [29130] [36646] [39870] [60860] Vandetanib: (Major) Avoid coadministration of lopinavir with vandetanib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Interrupt or dose reduce vandetanib if QT prolongation occurs. Vandetanib can prolong the QT interval in a concentration-dependent manner; torsade de pointes (TdP) and sudden death have been reported in patients receiving vandetanib. Lopinavir is associated with QT prolongation. [28341] [43901] [65157] [65170] Vardenafil: (Major) Avoid coadministration of lopinavir with vardenafil due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs are associated with QT prolongation. [28216] [28341] [41124] [46638] [65157] [65170] (Major) Do not use vardenafil orally disintegrating tablets with ritonavir due to increased vardenafil exposure; do not exceed a single dose of 2.5 mg per 72-hour period of vardenafil oral tablets. Vardenafil is primarily metabolized by CYP3A4/5; ritonavir is a strong CYP3A4 inhibitor. Coadministration of ritonavir with vardenafil resulted in a 49-fold increase in vardenafil AUC and a 13-fold increase in vardenafil Cmax. Concomitant use may increase the risk of vardenafil-related adverse effects, such as prolonged erection or QT prolongation. [28216] [41124] [46638] [47165] Vemurafenib: (Major) Avoid coadministration of lopinavir with vemurafenib due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs have been associated with QT prolongation. [28341] [45335] [56579] [65157] [65170] (Major) Avoid the concomitant use of vemurafenib and ritonavir; vemurafenib exposure may be increased resulting in an increased risk of adverse events, including QT prolongation. If use with ritonavir cannot be avoided, consider a vemurafenib dose reduction; monitor patients closely for the development of adverse events and dose reduce or discontinue therapy based on manufacturer guidance. Vemurafenib is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the exposure of vemurafenib by 40%. [45335] [47165] Venetoclax: (Major) Coadministration of ritonavir with venetoclax is contraindicated during the initiation and ramp-up phase in patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL); consider an alternative medication or adjust the venetoclax dose with close monitoring for toxicity (e.g., hematologic toxicity, GI toxicity, and tumor lysis syndrome) in patients receiving a steady daily dose of venetoclax if concurrent use is necessary. In patients with acute myeloid leukemia (AML), reduce the venetoclax dose and monitor for toxicity during concurrent use. Resume the original venetoclax dose 2 to 3 days after discontinuation of ritonavir. Specific venetoclax dosage adjustments are as follows: CLL/SLL patients at steady daily dose: 100 mg/day. AML patients: 10 mg on day 1, 20 mg on day 2, 50 mg on day 3, then 100 mg/day starting on day 4. Coadministration of ritonavir, a strong CYP3A, P-gp, and OATP1B1/B3 inhibitor increased the venetoclax AUC by 690% in a drug interaction study. [47165] [60706] Venlafaxine: (Major) Avoid coadministration of lopinavir with venlafaxine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Venlafaxine administration is associated with a possible risk of QT prolongation; torsade de pointes (TdP) has reported with postmarketing use. [10568] [28275] [28341] [65157] [65170] Verapamil: (Moderate) Concurrent administration of verapamil with ritonavir may result in elevated plasma concentrations of both drugs. Both verapamil and ritonavir are substrates and inhibitors of CYP3A4. Verapamil also inhibits the drug transporter P-glycoprotein (P-gp); ritonavir is a substrate of P-gp. Ritonavir also prolongs the PR interval in some patients; however, the impact on the PR interval of coadministration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers) has not been evaluated. If coadministration of these drugs is warranted, do so with caution and careful monitoring. Decreased calcium-channel blocker doses may be warranted. [11554] [40025] [5044] [56565] [6446] Vilazodone: (Major) Because CYP3A4 is the primary isoenzyme involved in the metabolism of vilazodone, the manufacturer of vilazodone recommends that the daily dose not exceed 20 mg/day during concurrent use of a strong CYP3A4 inhibitor, such as ritonavir. The original vilazodone dose can be resumed when the CYP3A4 inhibitor is discontinued. [28315] [43177] Vinblastine: (Major) Monitor for an earlier onset and/or increased severity of vinblastine-related adverse reactions, including myelosuppression, constipation, and peripheral neuropathy, if coadministration with ritonavir is necessary. Vinblastine is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. [28341] [28380] [34653] [34655] [47165] [56579] [57949] [59581] Vincristine Liposomal: (Major) The plasma concentrations of vincristine may be significantly elevated when administered concurrently with protease inhibitors. Consideration should be given to temporarily withholding the regimen in patients who develop significant hematological or gastrointestinal toxicity when protease inhibitors are coadministered with vincristine. Vincristine is a CYP3A4 and P-glycoprotein (P-gp) substrate; protease inhibitors are CYP3A4 inhibitors and some also inhibit P-gp. If the antiretroviral regimen needs to be withheld for a prolonged period, consider use of a revised regimen that does not include a CYP3A4 and P-gp inhibitor. [28155] [28498] [28731] [29472] [31320] [32432] [34654] [34655] [34656] [47165] [49123] [50768] [50769] [51080] [51432] [57949] Vincristine: (Major) The plasma concentrations of vincristine may be significantly elevated when administered concurrently with protease inhibitors. Consideration should be given to temporarily withholding the regimen in patients who develop significant hematological or gastrointestinal toxicity when protease inhibitors are coadministered with vincristine. Vincristine is a CYP3A4 and P-glycoprotein (P-gp) substrate; protease inhibitors are CYP3A4 inhibitors and some also inhibit P-gp. If the antiretroviral regimen needs to be withheld for a prolonged period, consider use of a revised regimen that does not include a CYP3A4 and P-gp inhibitor. [28155] [28498] [28731] [29472] [31320] [32432] [34654] [34655] [34656] [47165] [49123] [50768] [50769] [51080] [51432] [57949] Vinorelbine: (Moderate) Monitor for an earlier onset and/or increased severity of vinorelbine-related adverse reactions, including constipation and peripheral neuropathy, if coadministration with ritonavir is necessary. Vinorelbine is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. [47165] [56871] Vorapaxar: (Major) Avoid coadministration of vorapaxar and ritonavir. Increased serum concentrations of vorapaxar are possible when vorapaxar, a CYP3A4 substrate, is coadministered with ritonavir, a strong CYP3A inhibitor. Increased exposure to vorapaxar may increase the risk of bleeding complications. [57151] Voriconazole: (Major) Avoid coadministration of lopinavir with voriconazole due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Voriconazole has been associated with QT prolongation and rare cases of torsade de pointes. [28158] [28341] [46638] [54713] [65157] [65170] (Major) Coadministration of voriconazole and ritonavir at doses of 400 mg every 12 hours is contraindicated, and coadministration of voriconazole with ritonavir at doses of 100 mg should be avoided unless an assessment of the benefit to risk ratio justifies concurrent use. In one study, concurrent administration of voriconazole (400 mg every 12 hours for 1 day, then 200 mg every 12 hours for 8 days) and ritonavir (400 mg every 12 hours for 9 days) resulted in a 66% and 82% decrease in voriconazole Cmax and AUC, respectively. Low dose ritonavir (100 mg every 12 hours) decreased voriconazole Cmax and AUC concentrations by 24% and 39%, respectively. [28158] [28315] [46638] [47165] Vorinostat: (Major) Avoid coadministration of lopinavir with vorinostat due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Both drugs are associated with QT prolongation. [28341] [32789] [65157] [65170] (Major) The use of ritonavir could result in QT prolongation. Drugs with a possible risk for QT prolongation and TdP that should be used cautiously and with close monitoring with ritonavir include vorinostat. [32789] [47165] Voxelotor: (Major) Avoid coadministration of voxelotor and ritonavir as concurrent use may increase voxelotor exposure and lead to increased toxicity. If coadministration is unavoidable, reduce voxelotor dosage to 1,000 mg PO once daily. Voxelotor is a substrate of CYP3A4; ritonavir is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor is predicted to increase voxelotor exposure by 42% to 83%. [47165] [64778] Warfarin: (Moderate) Monitor the INR and adjust the dose as necessary if warfarin is coadministered with ritonavir: concurrent use may increase the risk of bleeding or reduce efficacy. Ritonavir is a CYP 3A4 inhibitor as well as a CYP1A4, CYP2C9, and CYP3A4 inducer. Warfarin is a substrate of CYP3A4, CYP2C9, and CYP1A2. [28549] [47165] Yohimbine: (Moderate) Concurrent administration of yohimbine with ritonavir may result in elevated yohimbine plasma concentrations. Yohimbine is metabolized by the hepatic isoenzymes CYP3A4 and CYP2D6; ritonavir is an inhibitor of these enzymes. Caution and close monitoring are advised if these drugs are administered together. [42997] [57066] [58664] Zafirlukast: (Moderate) Concurrent administration of zafirlukast with ritonavir may result in elevated plasma concentrations of ritonavir. In vitro, zafirlukast is an inhibitor of the hepatic isoenzyme CYP3A4. Ritonavir is a substrate for CYP3A4. Caution and close monitoring are advised if these drugs are administered together. [2129] [28222] [58664] [7806] [9700] Zalcitabine, ddC: (Major) Zalcitabine may cause peripheral neuropathy and coadministration with other drugs associated with peripheral neuropathy, such as ritonavir, should be avoided when possible. [1800] [6580] Zaleplon: (Moderate) Zaleplon is partially metabolized by CYP3A4, and concurrent use of strong CYP3A4 inhibitors, such as ritonavir, may decrease the clearance of zaleplon. Routine dosage adjustments of zaleplon are not required. Dosage adjustments should be made on an individual basis according to efficacy and tolerability. [29887] Zanubrutinib: (Major) Decrease the zanubrutinib dose to 80 mg PO once daily if coadministered with ritonavir. Coadministration may result in increased zanubrutinib exposure and toxicity (e.g., infection, bleeding, and atrial arrhythmias). Interrupt zanubrutinib therapy as recommended for adverse reactions. After discontinuation of ritonavir, resume the previous dose of zanubrutinib. Zanubrutinib is a CYP3A4 substrate; ritonavir is a strong CYP3A4 inhibitor. The AUC of zanubrutinib was increased by 278% when coadministered with another strong CYP3A4 inhibitor. [47165] [64748] Zidovudine, ZDV: (Minor) Since ritonavir induces glucuronidation, there is the potential for reduction in zidovudine, ZDV plasma concentrations during concurrent therapy with ritonavir. When coadministered with ritonavir, the AUC and Cmax of zidovudine, ZDV are decreased by 12% and 27%. The clinical significance of this interaction is unknown. [28315] [47165] [58664] Zileuton: (Moderate) Concurrent administration of zileuton with protease inhibitors may result in elevated zileuton plasma concentrations. Zileuton is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors block this enzyme. Caution and close monitoring are advised if these drugs are administered together [34597] [34598] [51119] Ziprasidone: (Major) Avoid coadministration of lopinavir with ziprasidone due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Clinical trial data indicate that ziprasidone causes QT prolongation; there are postmarketing reports of torsade de pointes (TdP) in patients with multiple confounding factors. [28233] [28341] [65157] [65170] (Major) Concomitant use of ziprasidone and ritonavir should be avoided due to the potential for additive QT prolongation. Clinical trial data indicate that ziprasidone causes QT prolongation; there are postmarketing reports of torsade de pointes (TdP) in patients with multiple confounding factors. The use of ritonavir could result in QT prolongation. In addition, the plasma concentrations of ziprasidone may be elevated when administered concurrently with ritonavir. Clinical monitoring for adverse effects, such as extrapyramidal symptoms and CNS effects, is recommended during coadministration. Ritonavir is a strong CYP3A4 inhibitor and ziprasidone is a partial CYP3A4 substrate. Coadministration of another strong CYP3A4 inhibitor increased the AUC and Cmax of ziprasidone by about 35 to 40%. [28233] [47165] Zolmitriptan: (Moderate) Concurrent administration of zolmitriptan with ritonavir may result in elevated zolmitriptan plasma concentrations. Zolmitriptan is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together. [57037] [58664] Zolpidem: (Moderate) Consider decreasing the dose of zolpidem if coadministration with protease inhibitors is necessary. Zolpidem is a CYP3A4 substrate and protease inhibitors are strong CYP3A4 inhibitors. Coadministration with strong CYP3A4 inhibitors increased the AUC of zolpidem by 34% to 70%. [28001] [28315] [32432] [57789] Zonisamide: (Moderate) Concurrent administration of zonisamide with ritonavir may result in elevated plasma concentrations of both zonisamide and ritonavir. Zonisamide is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Additionally, zonisamide is a weak inhibitor of P-gp, and ritonavir is a substrate of P-gp. There is theoretical potential for zonisamide to affect the pharmacokinetics of drugs that are P-gp substrates. Use caution when starting or stopping zonisamide or changing the zonisamide dosage in patients also receiving drugs which are P-gp substrates. Caution and close monitoring are advised if these drugs are administered together. [28843] [58664]
Revision Date: 09/24/2020, 02:28:00 AM

References

141 - Monahan BP, Ferguson CL, Killeavy ES, et al. Torsades de pointes occurring in association with terfenadine use. JAMA 1990;264:2788-90.1299 - Centers for Disease Control and Prevention (CDC). Notice to Readers: Updated guidelines for the use of rifamycins for the treatment of tuberculosis among HIV-infected patients taking protease inhibitors or nonnucleoside reverse transcriptase inhibitors. MMWR 2004;53:37. Available on the World Wide Web at http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5302a6.htm.1800 - US Department of Health and Human Services (DHHS) and National Institutes of Health (NIH). The Living Document: Guidelines for the use of antiretroviral agents in HIV-infected adults and adolescents. Retrieved March 18, 2008. Available on the World Wide Web at www.aidsinfo.nih.gov.1802 - Baselga J, Albanell J, Molina MA, et al. Mechanism of action of trastuzumab and scientific update. Semin Oncol 2001;28(5 Suppl 16):4-11.2129 - Katial RK, Stelzle RC, Bonner MW, et al. A drug interaction between zafirlukast and theophylline. Arch Intern Med 1998;158:1713-5.2356 - Piscitelli SC, Vogel S, Figg WD, et al. Alteration in indinavir clearance during interleukin-2 infusions in patients infected with the human immunodeficieny virus. Pharmacotherapy 1998;18:1212-6.2357 - Brinkman K, Huysmans F, Burger DM. Pharmacokinetic interaction between saquinavir and cyclosporine. Ann Intern Med 1998;129:914-5.2546 - Harrington RD, Woodward JA, Hooton TM, et al. Life-threatening interactions between HIV-1 protease inhibitors and the illicit drugs MDMA and gamma-hydroxybutyrate. Arch Intern Med 1999;159:2221-4.2548 - Hall MCS, Ahmad S. Interaction between sildenafil and HIV-1 combination therapy. Lancet 1999;353;2071-2.2718 - Piscitelli SC, Burstein AH, Alfaro MS. Indinavir concentrations and St. John's wort. Lancet 2000;355:547-48.4190 - Benedetti MS. Enzyme induction and inhibition by new antiepileptic drugs: a review of human studies. Fundam Clin Pharmacol 2000;14:301-19.4194 - Piscitelli SC, Gallicano KD. Interactions among drugs for HIV and opportunistic infections. N Engl J Med 2001;344:984-96.4718 - Hansten PD, Horn JR. Cytochrome P450 Enzymes and Drug Interactions, Table of Cytochrome P450 Substrates, Inhibitors, Inducers and P-glycoprotein, with Footnotes. In: The Top 100 Drug Interactions - A guide to Patient Management. 2008 Edition. Freeland, WA: H&H Publications; 2008:142-157.4865 - Reyataz (atazanavir) package insert. Princeton, NJ: Bristol-Myers Squibb Company; 2020 Sept.4935 - Henderson L, Yue QY, Bergquist C, et al. St John's wort (Hypericum perforatum): drug interactions and clinical outcomes. Br J Clin Pharmacol 2002;54:349-56.4951 - CredibleMeds. Drugs to avoid in congenital long QT. Available on the World Wide Web at http://www.crediblemeds.org.4968 - Halfan (halofantrine) package insert. Philadelphia, PA: Smith Kline Beecham Pharmaceuticals; 2001 Oct.4998 - propranolol tablet package insert. Huntsville, AL: Qualitest Pharmaceuticals; 2011 Jun.5018 - Migranal® (dihydroergotamine mesylate) nasal spray package insert. Aliso Viejo, CA: Valeant Pharmaceuticals; 2007 Jun.5043 - Ultram (tramadol immediate-release tablets) package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc.; 2019 Oct.5044 - Norvir (ritonavir capsules) package insert. North Chicago, IL: AbbVie Inc; 2019 Dec.5070 - Kaletra (lopinavir; ritonavir) tablet and solution package insert. North Chicago, IL: AbbVie Inc; 2020 Mar.5074 - Agenerase® (amprenavir) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2005 Nov.5110 - Phillips E, Rachlis A, Ito S. Digoxin toxicity and ritonavir: a drug interaction mediated through p-glycoprotein? AIDS 2003;17:1577-8.5149 - Owens RC Jr. Risk assessment for antimicrobial agent-induced QTc interval prolongation and torsades de pointes. Pharmacotherapy 2001;21:301-19.5150 - Iannini PB. Cardiotoxicity of macrolides, ketolides and fluoroquinolones that prolong the QTc interval. Expert Opin Drug Saf 2002;1:121-8.5162 - Roden, DM. Drug-induced prolongation of the QT interval. New Engl J Med 2004;350:1013-22.5172 - Sustiva (efavirenz) package insert. Princeton, NJ: Bristol-Myers Squibb Company; 2019 Oct.5206 - Rescriptor (delavirdine) package insert. Research Triangle Park, NC: ViiV Healthcare; 2012 Aug.5222 - Viramune (nevirapine) package insert. Ridgefield, CT: Boehringer Ingelheim Pharmaceuticals, Inc.; 2011 Mar.5224 - Neutrexin (trimetrexate) package insert. Gaithersburg, MD: MedImmune Oncology, Inc.; 2005 Jan.5267 - Coreg (carvedilol) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2017 Sept.5269 - Toprol-XL (metoprolol succinate) package insert. Wilmington, DE: AstraZeneca Pharmaceuticals LP; 2014 May.5270 - Blocadren (timolol maleate) package insert. Whitehouse Station, NJ: Merck and Co., Inc.; 2002 Mar.5286 - Tanaka E. Clinically significant pharmacokinetic drug interactions with benzodiazepines. J Clin Pharm Ther 1999;24:347-55.5335 - Mevacor (lovastatin) package insert. Whitehouse Station, NJ: Merck & Co., Inc.; 2012 Oct.5339 - Cozaar (losartan potassium) package insert. Whitehouse Station, NJ: Merck & Co., Inc.; 2018 Oct.5414 - Nefazodone tablet package insert. North Wales, PA: Teva Pharmaceuticals USA, Inc.; 2015 Sept.5491 - Maprotiline HCl tablet package insert. Morgantown WV: Mylan Pharmaceuticals Inc; 2014 Dec.5542 - Brachtendorf L, Jetter A, Beckurts KT, et al. Cytochrome P450 enzymes contributing to demethylation of maprotiline in man. Pharmacol Toxicol 2002;90:144-9.5623 - D.H.E. 45® (dihydroergotamine mesylate) package insert. Stein, Switzerland: Novartis Pharmaceuticals AG; 2002 Sep.5637 - Chirocaine (levobupivacaine) package insert. Stamford, CT: Purdue Pharma L.P.; 2001 Nov.5747 - Lexiva (fosamprenavir calcium) package insert. Research Triangle Park, NC: ViiV Healthcare; 2019 Mar5772 - Dresser GK, Spence JD, Bailey DG. Pharmacokinetic-pharmacodynamic consequences and clinical relevance of cytochrome P450 3A4 inhibition. Clin Pharmacokinet 2000;38:41-57.5831 - Serentil (mesoridazine) package insert. Ridgefield, CT: Boehringer Ingelheim Pharmaceuticals, Inc.; 2001 March.5911 - Wang JJ, Lee CL, Pan TM. Improvement of monacolin K, gama-aminobutyric acid and citrinin production ratio as a function of environmental conditions of Monascus purpureus NTU 601. J Ind Microbiol Biotechnol 2003;30:669-76.5936 - Sandimmune (cyclosporine) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2015 Mar.6265 - Nexium (esomeprazole) capsules, granules package insert. Wilmington, DE: AstraZeneca; 2018 June.6352 - Mobic (meloxicam) package insert. Ridgefield, CT: Boehringer Ingelheim Pharmaceuticals, Inc.; 2016 Jun.6446 - Covera-HS (verapamil hydrochloride tablets) package insert. New York, NY: Pfizer Inc.; 2011 Oct.6580 - Hivid (zalcitabine) package insert. Nutley, NJ: Roche Laboratories, Inc.; 2001 Sep.7238 - Apidra (Insulin glulisine) package insert. Kansas City, MO: Aventis Pharmaceuticals, Inc.; 2004 Apr.7335 - Luna B, Feinglos MN. Drug-induced hyperglycemia. JAMA 2001;286:1945-8.7573 - Gabitril (tiagabine) package insert. North Wales, PA: Teva Pharmaceuticals USA, Inc.; 2016 Aug.7731 - Nor-QD tablets (norethindrone) package insert. Parsippany, NJ: Watson Pharma, Inc.; 2011 Jul.7806 - Walsky RL, Gaman EA, Obach RS. Examination of 209 drugs for inhibition of cytochrome P450 2C8. J Clin Pharmacol 2005;45:68-78.8102 - Aptivus (tipranavir) package insert. Ridgefield, CT: Boehringer Ingelheim; 2020 Jun.8143 - Rozerem (ramelteon) package insert. Lincolnshire, IL: Takeda Pharmaceuticals; 2010 Nov.8145 - Cajochen C. TAK-375 Takeda. Curr Opin Investig Drugs 2005;6:114-21.8650 - Sheehan NL, Brouillette MJ, Delisle MS, et al. Possible interaction between lopinavir/ritonavir and valproic acid exacerbates bipolar disorder. Ann Pharmacother. 2006;40:147-50.9126 - Fosrenol (lanthanum carbonate) package insert. Wayne, PA: Shire US Inc.; 2005 Nov.9316 - Tramadol hydrochloride extended-release tablets package insert. Morgantown, WV: Mylan Pharmaceuticals, Inc.; 2020 Jul.9700 - Jaakkola T, Backman JT, Neuvonen M, et al. Montelukast and zafirlukast do not affect the pharmacokinetics of the CYP2C8 substrate pioglitazone. Eur J Clin Pharmacol 2006;62:503-9.10415 - Ixempra (ixabepilone) for injection package insert. Princeton, NJ: Bristol-Myers Squibb Company; 2011 Oct.10568 - Effexor XR (venlafaxine extended-release capsules) package insert. Philadelphia, PA: Wyeth Pharmaceuticals, Inc; 2017 Dec.11181 - Tang W, Stearns RA, Wang RW, et al. Roles of human hepatic cytochrome P450s 2C9 and 3A4 in the metabolic activation of diclofenac. Chem Res Toxicol 1999;12:192-9.11191 - Giao PT, de Vries PJ. Pharmacokinetic interactions of antimalarial agents. Clin Pharmacokinet 2001;40:343-73.11312 - Yasuda K, Ranade A, Venkataramanan R, et al. A comprehensive in vitro and in silico analysis of antibiotics that activate pregnane X receptor and induce CYP3A4 in liver and intestine. Drug Metab Dispos 2008;36:1689-97.11313 - Lang CC, Jamal SK, Mohamed Z, et al. Evidence of an interaction between nifedipine and nafcillin in humans. Br J Clin Pharmacol 2003;55:588-90.11379 - Barkin RL, Barkin SJ, Barkin DS. Propoxyphene (dextropropoxyphene): a critical review of a weak opioid analgesic that should remain in antiquity. Am J Ther 2006;13:534-42.11397 - Toviaz (fesoterodine fumarate) ER tablets package insert. New York, NY: Pfizer, Inc.; 2017 Nov.11416 - Lee CG, Gottesman MM, Cardarelli CO. HIV-1 protease inhibitors are substrates for the MDR1 multidrug transporter. Biochemistry 1998;37:3594-601.11417 - Storch CH, Theile D, Lindenmaier H, et al. Comparison of inhibitory activity of anti-HIV drugs on P-glycoprotein. Biochem Pharmacol 2007;73:1573-81.11418 - Choo EF, Leake B, Wandel C, et al. Pharmacological inhibition of P-glycoprotein transport enhances the distribution of HIV-1 protease inhibitors into brain and testes. Drug Metab Dispos 2000;28:655-60.11537 - Katoh M, Nakajima M, Yamazaki H, et al. Inhibitory potencies of 1,4-dihydropyridine calcium antagonists to P-glycoprotein-mediated transport: comparison with the effects of CYP3A4. Pharm Res 2000;17:1189-97.11554 - Zhou SF. Drugs behave as substrates, inhibitors and inducers of human cytochrome P450 3A4. Curr Drug Metab 2008;9:310-22.11580 - Krauser JA, Guengerich FP. Cytochrome P450 3A4-catalyzed testosterone 6beta-hydroxylation stereochemistry, kinetic deuterium isotope effects, and rate-limiting steps. J Biol Chem 2005;280:19496-506.11581 - Barnes KM, Dickstein B, Cutler GB Jr, et al. Steroid transport, accumulation, and antagonism of P-glycoprotein in multidrug-resistant cells. Biochemistry 1996;35:4820-7.22256 - Risperdal Consta (risperidone long-acting injection) package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc.; 2020 Jan.23500 - Wilt JL, Minnema AM, Johnson RF, et al. Torsade de pointes associated with the use of intravenous haloperidol. Ann Intern Med 1993;119:391-4.23620 - Green PT, Reents S, Harman E, et al. Pentamidine-induced torsades de pointes in a renal tranplant recipient with Pneumocystis carinii pneumonia. S Med J 1990;83:481-4.23774 - Lui HK, Lee G, Dietrich P, et al. Flecainide-induced QT prolongation and ventricular tachycardia. Am Heart J 1982;103:567-9.23778 - Wharton JM, Demopulos PA, Goldschlager N. Torsade de pointes during administration of pentamidine isethionate. Am J Med 1987;83:571-6.23779 - Kriwisky M, Perry GY, Tarchitsky D, et al. Haloperidol-induced torsades de pointes. Chest 1990;98:482-3.24859 - Davis JL, et al. Iritis and hypotony after treatment with intravenous cidofovir for cytomegalovirus retinitis. Arch Ophthal 1997;115:733-7.25398 - Melchart D, Linde K, Worku F, et al. Results of five randomized studies on the immunomodulatory activity of preparations of Echinacea. J Altern Complement Med 1995;1:145-60.25460 - Tolman KG. Hepatotoxicity of non-narcotic analgesics. Am J Med 1998;105:13S-19S.25887 - Harrington RD, Woodward JA, Hooton TM, et al. Life-threatening interactions between HIV-1 protease inhibitors and the illicit drugs MDMA and gamma-hydroxybutyrate. Arch Intern Med 1999;159:2221-4.26120 - Hsu A, Granneman GR, Cao G, et al. Pharmacokinetic interaction between ritonavir and indinavir in healthy volunteers. Antimicrob Agents Chemother 1998;42:2784-91.26121 - van Heeswijk RP, Veldkamp AI, Hoetelmans RM, et al. The steady-state plasma pharmacokinetics of indinavir alone and in combination with a low dose of ritonavir in twice daily dosing regimens in HIV-1 infected individuals. AIDS. 1999; 13:F95-9.26403 - Olkkola KT, Palkama VJ, Neuvonen PJ. Ritonavir's role in reducing fentanyl clearance and prolonging its half-life. Anesthesiology 1999;91:681-5.27275 - Penzak SR, Hon YY, Lawhorn WD, et al. Influence of ritonavir on olanzapine pharmacokinetics in healthy volunteers. J Clin Psychopharmacol 2002;22:366-70.27480 - Ridtitid W, Wongnawa M, Mahatthanatrakul W, et al. Rifampin markedly decreases plasma concentrations of praziquantel in healthy volunteers. Clin Pharmacol Ther 2002;72:505-13.27493 - Piscitelli SC, Gallicano KD. Interactions among drugs for HIV and opportunistic infections. N Engl J Med 2001;344:984-96.27494 - Hsu A, Granneman GR, Bertz RJ. Ritonavir: clinical pharmacokinetics and interactions with other anti-HIV agents. Clin Pharmacokinet 1998;35:275-91.27896 - Bachmann K, He Y, Sarver JG, et al. Characterization of the cytochrome P450 enzymes involved in the in vitro metabolism of ethosuximide by human hepatic microsomal enzymes. Xenobiotica 2003;33:265-76.27971 - Xenical (orlistat) package insert. South San Francisco, CA: Genentech USA, Inc.; 2016 Jun.27982 - Ketoconazole tablets package insert. Morgantown, WV: Mylan Pharmaceuticals, Inc.; 2017 Sept.27983 - Sporanox (itraconazole) capsules package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc.; 2019 Mar.27988 - Crestor (rosuvastatin) package insert. Wilmington, DE: AstraZeneca Pharmaceuticals LP; 2020 May.27990 - Inspra (eplerenone) package insert. New York, NY: Pfizer Inc; 2018 May.28001 - Hansten PD, Horn JR. Cytochrome P450 Enzymes and Drug Interactions, Table of Cytochrome P450 Substrates, Inhibitors, Inducers and P-glycoprotein, with Footnotes. In: The Top 100 Drug Interactions - A guide to Patient Management. 2008 Edition. Freeland, WA: H&H Publications; 2008:142-157.28003 - Mifeprex (mifepristone, RU-486) package insert. New York, NY: Danco Laboratories, LLC; 2019 Apr.28040 - Xanax (alprazolam tablet) package insert. New York, NY: Pharmacia & Upjohn Company; 2017 Jan.28058 - Wellbutrin XL (bupropion) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2019 Nov.28100 - Manyike PT, Kharasch ED, Kalhorn TF, et al. Contribution of CYP2E1 and CYP3A to acetaminophen reactive metabolite formation. Clin Pharmacol Ther 2000;67:275-282.28142 - Reyataz (atazanavir) package insert. Princeton, NJ: Bristol-Myers Squibb Company; 2020 Sept.28155 - Chan JD. Pharmacokinetic drug interactions of vinca alkaloids: summary of case reports. Pharmacotherapy 1998;18:1304-7.28156 - Ketek (telithromycin) package insert. Bridgewater, NJ: Sanofi-Aventis Pharmaceuticals; 2015 Oct.28158 - VFEND (voriconazole) tablets, suspension, and injection package insert. New York, NY: Pfizer Inc; 2020 Sept.28172 - Avandia (rosiglitazone) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2019 Feb.28193 - Viread (tenofovir disoproxil fumarate) package insert. Foster City, CA: Gilead Sciences, Inc; 2019 Apr.28216 - Levitra (vardenafil) package insert. Kenilworth, NJ: Schering-Plough; 2017 Aug.28220 - Cialis (tadalafil) package insert. Indianapolis, IN: Lilly ICOS, LLC; 2018 Feb.28221 - Tikosyn (dofetilide) package insert. New York, NY: Pfizer Labs; 2019 Aug.28222 - Accolate (zafirlukast) package insert. Wilmington, DE: AstraZeneca; 2013 June.28224 - Pacerone (amiodarone) tablets package insert. Maple Grove, MN: Upsher-Smith Laboratories, LLC.; 2018 Nov.28225 - CredibleMeds. Drugs to avoid in congenital long QT. Available on the World Wide Web at http://www.crediblemeds.org.28226 - Trisenox (arsenic trioxide) package insert. Frazer, PA: Cephalon, Inc; 2010 Jun.28228 - Norpace and Norpace CR (disopyramide) package insert. Chicago, IL: G.D. Searle LLC division of Pfizer Inc; 2016 Aug.28229 - Demaziere J, Fourcade JM, Busseuil CT, et al. The hazards of chloroquine self prescription in west Africa. J Toxicol Clin Toxicol 1995;33:369-70.28230 - Mansfield RJ, Thomas RD. Recurrent syncope. Drug induced long QT syndrome. Postgrad Med J 2001;77:344, 352-3.28231 - Pinski SL, Eguia LE, Trohman RG. What is the minimal pacing rate that prevents torsades de pointes? Insights from patients with permanent pacemakers. Pacing Clin Electrophysiol 2002;25:1612-5.28233 - Geodon (ziprasidone) package insert. New York, NY: Pfizer: 2020 Jan.28234 - Betapace (sotalol) package insert. Wayne, NJ: Berlex Laboratories; 2011 Aug.28235 - Richards JR, Schneir AB. Droperidol in the emergency department: is it safe? J Emerg Med 2003;24:441-7.28236 - Kao LW, Kirk MA, Evers SJ, et al. Droperidol, QT prolongation, and sudden death: what is the evidence? Ann Emerg Med 2003;41:546-58.28237 - Food and Drug Administration Press Office. FDA strengthens warnings for droperidol. FDA Talk Paper. December 5, 2001. Accessed: April 16, 2004. Available on the World Wide Web at: http://www.fda.gov/bbs/topics/answers/2001/ans01123.html28238 - Biaxin (clarithromycin) package insert. North Chicago, IL: AbbVie, Inc.; 2019 Sep.28240 - Gleevec (imatinib mesylate) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2014 May.28250 - Procanbid (procainamide) package insert. Bristol, TN: Monarch Pharmaceuticals; 2002 Jan.28260 - Paxil (paroxetine) tablet package insert. Research Triangle Park, NC: GlaxoSmithKline; 2017 Jan.28261 - Uroxatral (alfuzosin) package insert. Cary, NC: Covis Pharmaceuticals, Inc.; 2013 Sep.28262 - Clozaril (clozapine) tablets package insert. Rosemont, PA: HLS Therapeutics (USA), Inc. (Clozaril is a registered trademark of Novartis AG); 2017 Feb.28269 - Celexa (citalopram) package insert. Irvine, CA: Allergan USA, Inc.; 2019 Jan.28270 - Lexapro (escitalopram) package insert. Irvine, CA: Allergan USA, Inc.; 2020 Aug.28272 - Lanoxin (digoxin) tablets package insert. St. Michael, Barbados: Concordia Pharmaceuticals Inc.; 2019 Feb.28275 - Effexor (venlafaxine) package insert. Philadelphia, PA: Wyeth Pharmaceuticals, Inc.; 2017 Dec.28287 - Rythmol SR (propafenone hydrochloride) capsule extended release package insert. Research Triangle Park, NC: GlaxoSmithKline; 2018 Nov.28293 - Thioridazine package insert. Morgantown, WV: Mylan Pharmaceuticals Inc.; 2016 Nov.28301 - Mefloquine package insert. Princeton, NJ: Sandoz Inc.; 2013 Jul.28307 - Haldol injection for immediate release (haloperidol) package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc.; 2020 Feb.28315 - Norvir (ritonavir capsules) package insert. North Chicago, IL: AbbVie Inc; 2019 Dec.28318 - Xopenex (levalbuterol) package insert. Marlborough, MA: Sepracor Inc.; 2009 Feb.28319 - Krantz MJ, Kutinsky IB, Robertson AD, et al. Dose-related effects of methadone on QT prolongation in a series of patients with torsade de pointes. Pharmacotherapy 2003;23:802-5.28320 - Walker PW, Klein D, Kasza L. High dose methadone and ventricular arrhythmias: a report of three cases. Pain 2003;103:321-4.28321 - Kornick CA, Kilborn MJ, Santiago-Palma J, et al. QTc interval prolongation associated with intravenous methadone. Pain 2003;105:499-506.28322 - Gil M, Sala M, Anguera I, et al. QT prolongation and Torsades de Pointes in patients infected with human immunodeficiency virus and treated with methadone. Am J Cardiol 2003;92:995-7.28337 - Parlodel (bromocriptine) tablets and capsules package insert. Parsippany, NJ: Validus Pharmaceuticals LLC; 2019 Dec.28341 - Kaletra (lopinavir; ritonavir) tablet and solution package insert. North Chicago, IL: AbbVie Inc; 2020 Mar.28343 - Zoloft (sertraline) package insert. New York, NY: Pfizer; 2019 Apr.28345 - Agenerase® (amprenavir) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2005 Nov.28377 - Foscavir (foscarnet) package insert. Lake Forest, IL: Clinigen Healthcare, Ltd.; 2017 Feb.28378 - Topamax (topiramate) package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc.; 2020 Jun.28380 - Phillips E, Rachlis A, Ito S. Digoxin toxicity and ritonavir: a drug interaction mediated through p-glycoprotein? AIDS 2003;17:1577-8.28382 - Lotronex (alosetron) package insert. San Diego, CA: Promethus Laboratories, Inc.; 2019 April.28383 - Velcade (bortezomib) injection package insert. Cambridge, MA: Millennium Pharmaceuticals, Inc.; 2019 Apr.28405 - Strattera (atomoxetine) package insert. Indianapolis, IN: Eli Lilly and Company; 2020 Feb.28413 - Prevpac (amoxicillin, clarithromycin, lansoprazole) package insert. Deerfield, IL: Takeda Pharmaceuticals America, Inc.; 2018 June.28414 - Risperdal (risperidone tablets, oral solution, and orally disintegrating tablets) package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc.; 2020 Jan.28415 - Nora Goldschlager, Andrew E Epstein, Blair P Grubb, et al. Etiologic considerations in the patient with syncope and an apparently normal heart. Arch Intern Med 2003;163:151-62.28416 - Hansten PD, Horn JR. Drug Interactions with Drugs that Increase QTc Intervals. In: The Top 100 Drug Interactions - A Guide to Patient Management. 2007 Edition. Freeland, WA: H&H Publications; 2007:144-8.28417 - Hoehns JD, Stanford RH, Geraets DR, et al. Torsades de pointes associated with chlorpromazine: case report and review of associated ventricular arrhythmias. Pharmacotherapy 2001;21:871-83.28419 - Owens RC Jr. Risk assessment for antimicrobial agent-induced QTc interval prolongation and torsades de pointes. Pharmacotherapy 2001;21:301-19.28420 - Iannini PB. Cardiotoxicity of macrolides, ketolides and fluoroquinolones that prolong the QTc interval. Expert Opin Drug Saf 2002;1:121-8.28421 - Levaquin (levofloxacin) tablet package insert. Titusville, NJ: Janssen Pharmaceutical, Inc.; 2020 Jun.28423 - Avelox (moxifloxacin) package insert. Whippany, NJ: Bayer HealthCare Pharmaceuticals Inc.; 2020 May.28424 - Factive (gemifloxacin mesylate) package insert. Toronto, ON: Merus Labs International, Inc.; 2019 May.28432 - Roden, DM. Drug-induced prolongation of the QT interval. New Engl J Med 2004;350:1013-22.28442 - Sustiva (efavirenz) package insert. Princeton, NJ: Bristol-Myers Squibb Company; 2019 Oct.28444 - Klonopin® (clonazepam) package insert. Nutley, NJ: Roche Laboratories, Inc; 2016 Mar.28451 - Lamictal (lamotrigine) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2020 Aug.28457 - Crouch MA, Limon L, Cassano AT. Clinical relevance and management of drug-related QT interval prolongation. Pharmacotherapy 2003;23:881-908.28458 - Schmeling WT, Warltier DC, McDonald DJ, et al. Prolongation of the QT interval by enflurane, isoflurane, and halothane in humans. Anesth Analg 1991;72:137-44.28467 - Serevent Diskus (salmeterol xinafoate inhalation powder) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2019 July.28476 - Rescriptor (delavirdine) package insert. Research Triangle Park, NC: ViiV Healthcare; 2012 Aug.28483 - Priftin (rifapentine) package insert. Bridgewater, NJ: Sanofi-Aventis Pharmaceuticals Inc.; 2020 Jun.28496 - Tracleer (bosentan) package insert. South San Francisco, CA: Actelion Pharmaceuticals US, Inc.; 2019 May.28498 - Lum BL, Gosland MP, Kaubish S, et al. Molecular targets in oncology; implications of the multidrug resistance gene. Pharmacotherapy 1993;13:88-109.28501 - Buspirone tablets package insert. North Wales, PA: Teva Pharmaceuticals USA Inc.; 2016 Dec.28549 - Coumadin (warfarin tablets) package insert. Princeton, NJ: Bristol-Myers Squibb Company; 2017 Aug.28556 - Tanaka E. Clinically significant pharmacokinetic drug interactions with benzodiazepines. J Clin Pharm Ther 1999;24:347-55.28558 - Amoxapine package insert. Parsippany, NJ: Actavis Pharma, Inc.; 2015 Feb.28581 - Flagyl (metronidazole tablets) package insert. New York, NY: Pfizer, Inc.; 2018 Jan.28592 - Zoladex (goserelin acetate 3.6 mg implant) package insert. Lake Forest, IL: TerSera Therapeutics LLC; 2019 Feb.28604 - Mevacor (lovastatin) package insert. Whitehouse Station, NJ: Merck & Co., Inc.; 2012 Oct.28605 - Zocor (simvastatin) package insert. Whitehouse Station, NJ: Merck & Co., Inc.; 2019 Oct.28610 - Rapamune (sirolimus) package insert. Philadelphia, PA: Wyeth Pharmaceuticals Inc.; 2019 J Aug.28611 - Prograf (tacrolimus) capsules, injection, and granules for oral suspension package insert. Astellas Pharma US, Inc.: Northbrook, IL; 2019 Jun.28661 - Apokyn and Apokyn Pen (apomorphine) injection package insert. Louisville, KY: US WorldMeds LLC; 2020 Apr.28674 - Diflucan oral tablet and suspension (fluconazole) package insert. New York, NY: Pfizer; 2020 Sept.28729 - Lipitor (atorvastatin calcium) package insert. New York, NY: Pfizer; 2019 Apr.28731 - Crixivan (indinavir) package insert. Whitehouse Station, NJ: Merck & Co., Inc.; 2016 Sept.28737 - Inapsine (Droperidol) Injection package insert. Lake Forest, IL: Akorn, Inc.; 2011 Oct.28752 - Thevenin J, Da Costa A, Roche F, et al. Flecainide induced ventricular tachycardia (torsades de pointes). Pacing Clin Electrophysiol 2003;26:1907-8.28754 - Loeckinger A, Kleinsasser A, Maier S, et al. Sustained prolongation of the QTc interval after anesthesia with sevoflurane in infants during the first 6 months of life. Anesthesiology 2003;98:639-42.28755 - Kleinsasser A, Loeckinger A, Lindner KH, et al. Reversing sevoflurane-associated Q-Tc prolongation by changing to propofol. Anaesthesia 2001;56:248-50.28756 - Kuenszberg E, Loeckinger A, Kleinsasser A, et al. Sevoflurane progressively prolongs the QT interval in unpremedicated female adults. Eur J Anaesthesiol 2000;17:662-4.28759 - Maprotiline HCl tablet package insert. Morgantown WV: Mylan Pharmaceuticals Inc; 2014 Dec.28774 - Williams D, Feely J. Pharmacokinetic-pharmacodynamic drug interactions with HMG-CoA reductase inhibitors. Clin Pharmacokinet 2002;41:343-370.28784 - Hepsera (adefovir dipivoxil) package insert. Foster City, CA: Gilead Sciences, Inc.; 2018 Dec.28785 - Zyprexa (olanzapine, all formulations) package insert. Indianapolis, IN: Eli Lilly and Company; 2020 Apr.28822 - Fareston (toremifene citrate) tablets package insert. Bedminster, NJ: Kyowa Kirin Inc.; 2017 May.28839 - Viracept (nelfinavir mesylate) package insert. Research Triangle Park, NC: ViiV Healthcare Company; 2016 Sept.28843 - Zonegran (zonisamide) package insert. Dublin, Ireland: Concordia Pharmaceuticals, Inc.; 2020 Apr.28855 - Zithromax (azithromycin 250 mg and 500 mg tablets and azithromycin oral suspension) package insert. New York, NY: Pfizer Inc.; 2019 Apr.28874 - Zyrtec (cetirizine) package insert. New York, NY: Pfizer Labs; 2004 Mar.28875 - Avodart (dutasteride soft gelatin capsules) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2020 Jan.28879 - Pentamidine isethionate injection package insert. Manasquan, NJ: Seton Pharma, LLC; 2014 Jan.28978 - Michalets EL, Williams CR. Drug interactions with cisapride: clinical implications. Clin Pharmacokinet 2000;39:49-75.28995 - Invirase (saquinavir) package insert. South San Francisco, CA: Genentech Inc.; 2020 Sept.29012 - Lexiva (fosamprenavir calcium) package insert. Research Triangle Park, NC: ViiV Healthcare; 2019 Mar29014 - Trileptal (oxcarbazepine) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2019 Jan.29068 - Procardia (nifedipine) package insert. New York, NY: Pfizer Labs, Inc.; 2015 Jan.29082 - Nimodipine capsule package insert. Livonia, MI: Major Pharmaceuticals; 2015 Dec.29090 - Norvasc (amlodipine) package insert. New York, NY: Pfizer Labs; 2019 Jan.29118 - Seroquel (quetiapine fumarate) package insert. Wilmington, DE: AstraZeneca Pharmaceuticals LP; 2020 Sept.29128 - DynaCirc CR (isradipine) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2009 Feb.29130 - Diovan (valsartan) tablets package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2019 Jun.29219 - Ramamoorthy Y, Yu AM, Suh N, et al. Reduced (+/-)-3,4-methylenedioxymethamphetamine ("Ecstasy") metabolism with cytochrome P450 2D6 inhibitors and pharmacogenetic variants in vitro. Biochem Pharmacol. 2002;63:2111-9.29289 - Xifaxan (rifaximin) package insert. Raleigh, NC: Salix Pharmaceuticals, Inc.; 2017 Dec.29472 - Oncovin (vincristine sulfate injection, USP) package insert. Indianapolis, IN: Eli Lilly and Company; 1997 Oct.29564 - Prilosec (omeprazole) package insert. Wilmington, DE: AstraZeneca; 2019 April.29623 - Duragesic (fentanyl transdermal system) package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc.; 2019 Oct.29624 - Park JY, Kim KA, Kim SL. Chloramphenicol is a potent inhibitor of cytochrome P450 isoforms CYP2C19 and CYP3A4 in human liver microsomes. Antimicrob Agents Chemother 2003;47:3464-9.29640 - Aricept (donepezil hydrochloride) package insert. Woodcliff Lake, NJ: Eisai Co., Ltd.; 2017 March.29677 - Flomax (tamsulosin) package insert. Ridgefield, CT: Boehringer Ingelheim Pharmaceuticals, Inc.; 2014 Oct.29747 - Riluzole tablet package insert. Cranbury, NJ: Sun Pharmaceutical Industries Inc.; 2017 Jan.29751 - Niemi M, Kajosaari LI, Neuvonen M, et al. The CYP2C8 inhibitor trimethoprim increases the plasma concentrations of repaglinide in healthy subjects. Br J Clin Pharmacol 2004;57:441-7.29758 - Aralen (chloroquine) package insert. Bridgewater, NJ: Sanofi-aventis U.S. LLC.; 2018 Oct.29763 - Actiq (oral transmucosal fentanyl citrate) package insert. North Wales, PA: Teva Pharmaceuticals USA, Inc.; 2019 Oct.29796 - Ditropan XL (oxybutynin chloride) package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc.; 2019 Sept.29818 - Noroxin (norfloxacin) tablets package insert. Whitehouse Station, NJ: Merck and C., Inc.; 2016 Jul.29824 - Cardura (doxazosin) package insert. New York, NY:Pfizer;2016 Jun.29887 - Sonata (zaleplon) package insert. Bristol, TN: King Pharmaceuticals; 2019 Aug.29931 - Tindamax (tinidazole) package insert. San Antonio, TX: Mission Pharmacal; 2019 Jun.29964 - Gris-Peg (griseofulvin ultramicrosize) package insert. Bridgewater, NJ: Valeant Pharmaceuticals North America LLC; 2016 Apr..30015 - Medrol (methylprednisolone) package insert. New York, NY: Pharmacia and Upjohn Company; 2018 July.30106 - Imodium A-D Liquid and Caplets (loperamide HCL) consumer product labels. Fort Washington, PA: Johnson and Johnson Consumer Inc., McNeil Consumer Healthcare Division; 2019.30163 - Agrylin (anagrelide) capsules package insert. Lexington, MA: Shire US Inc.; 2020 Feb.30195 - Ding R, Tayrouz Y, Riedel KD, et al. Substantial pharmacokinetic interaction between digoxin and ritonavir in healthy volunteers. Clin Pharmacol Ther 2004;76:73-84.30282 - Synalgos-DC (aspirin; caffeine; dihydrocodeine) capsules package insert. Atlanta, GA: Mikart, Inc.; 2019 Oct.30314 - Rifadin capsules and injection (rifampin) package insert. Bridgewater, NJ: Sanofi-Aventis, LLC; 2020 May.30369 - Vantas (histrelin implant) package insert. Chadds Ford, PA: Endo Pharmaceuticals Solutions Inc.; 2019 Feb.30379 - Hycodan (hydrocodone bitartrate; homatropine methylbromide) package insert. Malvern, PA: Endo Pharmaceuticals Inc.; 2018 Jun.30391 - Hutchinson MR, Menelaou A, Foster DJ, et al. CYP2D6 and CYP3A4 involvement in the primary oxidative metabolism of hydrocodone by human liver microsomes. Br J Clin Pharmacol 2004;57:287-97.30413 - Prosom (estazolam) tablets package insert. North Chicago, IL: Abbott Laboratories; 2004 Jan.30431 - Marinol (dronabinol, THC) package insert. Marietta, GA: Unimed Pharmaceuticals, Inc.; 2017 Aug.30456 - German Commission E. Echinacea Purpurea herb, Echinaceae purpureae herrba, monograph Published March 2, 1989. In: Blumenthal, M et al ., eds. The complete German Commission E Monographs -Therapeutic Guide to Alternative Medicines. Boston MA: Integrative Medicine Communications for the American Botanical Council; 1998:122-3.30469 - Camptosar (irinotecan) package insert. Kalamazoo, MI: Pharmacia and Upjohn Company; 2020 Jan.30480 - Apidra (Insulin glulisine) package insert. Kansas City, MO: Aventis Pharmaceuticals, Inc.; 2004 Apr.30515 - Vesicare (solifenacin) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2012 Jul.30555 - Tarceva (erlotinib) package insert. Northbrook, IL: OSI Pharmaceuticals, LLC; 2016 Sept.30571 - Lunesta (eszopiclone) tablets package insert. Marlborough, MA: Sunovion Pharmaceuticals Inc; 2019 Aug.30575 - Luna B, Feinglos MN. Drug-induced hyperglycemia. JAMA 2001;286:1945-8.30585 - Pandit MK, Burke J, Gustafson AB, et al. Drug-induced disorders of glucose tolerance. Ann Intern Med 1993;118:529-39.30676 - Emend (aprepitant oral products) package insert. Whitehouse Station, NJ: Merck & Co.,Inc.; 2019 Nov.30711 - Enablex (darifenacin extended-release tablets) package insert. Irvine, CA: Allergan USA, Inc.; 2016 Sept.30738 - Ofloxacin tablets package insert. Sacramento, CA: Nivagen Pharmaceuticals, Inc.; 2019 Feb.30742 - Abraxane (paclitaxel protein-bound particles) injection package insert. Summit, NJ: Celgene Corporation; 2020 Aug.30802 - Hansten PD, Horn JR. Top 100 Drug Interactions Monographs. In: The Top 100 Drug Interactions - A guide to Patient Management. 2007 Edition. Freeland, WA: H&H Publications; 2007:4-141.30966 - Sufenta (sufentanil citrate injection) package insert. Lake Forest, IL: Akorn Pharmaceuticals, Inc.; 2019 Oct31112 - Detrol (tolterodine tartrate) package insert. New York, NY: Pharmacia and Upjohn Co., division of Pfizer; 2016 Nov.31240 - Tradjenta (linagliptin) package insert. Ridgefield, CT: Boehringer Ingelheim Pharmaceuticals Inc.; 2020 Mar.31266 - Zofran (ondansetron) injection package insert. Research Triangle Park, NC: GlaxoSmithKline; 2017 Mar.31281 - Bidstrup TB, Bjornsdottir I, Sidelmann UG, et al. CYP2C8 and CYP3A4 are the principal enzymes involved in the human in vitro biotransformation of the insulin secretagogue repaglinide. Br J Clin Pharmacol 2003;56:305-14.31320 - Aptivus (tipranavir) package insert. Ridgefield, CT: Boehringer Ingelheim; 2020 Jun.31359 - Rozerem (ramelteon) package insert. Lincolnshire, IL: Takeda Pharmaceuticals; 2010 Nov.31360 - Cajochen C. TAK-375 Takeda. Curr Opin Investig Drugs 2005;6:114-21.31403 - Qualaquin (quinine sulfate) capsules package insert. Cranbury, NJ: Sun Pharmaceutical Industries, Inc.; 2019 Jun.31649 - Mauss S, Valenti WA, DePamphilis JB, et al. Risk factors for hepatic decompensation in patients with HIV/HCV coinfection and liver cirrhosis during interferon-based therapy. AIDS 18;13:21-25.31723 - Kytril injection (granisetron) package insert. Nutley, NJ: Roche Pharmaceuticals; 2011 Nov.31749 - Adalat CC (nifedipine extended-release tablets) package insert. West Haven, CT: Bayer Pharmaceuticals Corporation; 2010 Aug.31764 - Vaprisol (conivaptan hydrochloride injection) package insert. Deerfield, IL: Baxter Healthcare Corporation; 2016 Oct.31807 - Exjade (deferasirox) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2020 Jul.31824 - Rhinocort Aqua (budesonide) nasal spray package insert. Wilmington, DE: AstraZeneca Pharmaceuticals LP; 2012 Feb.31832 - Nexavar (sorafenib) package insert. Wayne, NJ; Bayer HealthCare Pharmaceuticals Inc.; 2020 July.31869 - Axert (almotriptan) package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc.; 2017 May.31938 - Ranexa (ranolazine extended-release tablets) package insert. Foster City, CA: Gilead Sciences, Inc. 2019 Oct.31970 - Sunitinib (Sutent) package insert. New York, NY: Pfizer Labs; 2020 Aug.32387 - Sprycel (dasatinib) package insert. Princeton, NJ: Bristol-Myers Squibb Company; 2014 April.32432 - Prezista (darunavir) package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc.; 2019 May.32514 - Atripla (efavirenz; emtricitabine; tenofovir disoproxil fumarate) package insert. Foster City, CA: Gilead Sciences, Inc.; 2019 Oct.32723 - Noxafil (posaconazole) package insert. Whitehouse Station, NJ: Merck & Co. Inc.: 2020 Sept.32731 - Fentora (fentanyl buccal tablet) package insert. North Wales, PA: Teva Pharmaceuticals, Inc.; 2019 Oct.32732 - Stollberger C, Huber JO, Finsterer J. Antipsychotic drugs and QT prolongation. Int Clin Psychopharmacol 2005;20:243-51.32734 - Su KP, Lane HY, Chuang CL, et al. Olanzapine-induced QTc prolongation in a patient with wolff-parkinson-white syndrome. Schizophrenia Research 2004;66:191-2.32745 - Dineen S, Withrow K, Voronovitch L, et al. QTc prolongation and high-dose olanzapine. Psychosomatics 2003;44:174-5.32746 - Gurovich, I. QTc prolongation: chlorpromazine and high-dosage olanzapine. Can J Psychiatry 2003;48:348.32789 - Zolinza (vorinostat) capsules package insert. Whitehouse Station, NJ: Merck & Co., Inc.; 2018 Dec.32901 - Brovana (arformoterol tartrate) inhalation solution package insert. Marlborough, MA: Sunovion Pharmaceuticals, Inc..; 2019 May.33068 - Gajwani P, Pozuelo L, Tesar G, et al. QT interval prolongation associated with quetiapine (seroquel) overdose. Psychosomatics 2000;41:63-5.33072 - Beelen AP, Yeo KTJ, Lewis LD. Asymptomatic QTc prolongation associated with quetiapine fumarate overdose in a patient being treated with risperidone. Hum Exp Toxicol 2001;20:215-9.33074 - Furst BA, Champion KM, Pierre JM, et al. Possible association of QTc interval prolongation with co-administration of quetiapine and lovastatin. Biol Psychiatry 2002;51:264-5.33136 - Dolophine (methadone) package insert. Eatontown, NJ: West-Ward Pharmaceuticals Corp.; 2019 Oct.33192 - Tykerb (lapatinib) tablet package insert. Research Triangle Park, NC: GlaxoSmithKline; 2018 Dec.33200 - Tekturna (aliskiren) package insert. Orlando, FL: Noden Pharma USA Inc; 2020 Jun.33239 - Altabax (retapamulin) package insert. Exton PA: Almirall, LLC; 2019 Sep.33263 - Vyvanse (lisdexamfetamine) capsules and chewable tablets package insert. Lexington, MA: Shire US Inc.; 2017 July.33350 - Xyzal (levocetirizine) package insert. Bridgewater, NJ: Sanofi-Aventis U.S. LLC; 2019 April.33467 - Nuvigil (armodafinil) package insert. Frazer, PA: Cephalon Inc; 2017 Feb.33473 - Selzentry (maraviroc) package insert. Research Triangle Park, NC: ViiV Healthcare; 2018 July.33536 - Hycamtin (topotecan) capsules package insert. Research Triangle Park, NC: GlaxoSmithKline; 2018 Sept.33578 - Kruijtzer CMF, Beijnen JH, Rosing H, et al. Increased oral bioavailability of topotecanin combination with the breast cancer resistance protein and P-glycoprotein inhibitor GF120918. J Clin Oncol 2002;20:2943-50.33635 - Kuvan (sapropterin) package insert. Novato, CA: BioMarin Pharmaceutical Inc; 2020 March33654 - Codeine sulfate tablets package insert. Eatontown, NJ; West-Ward Pharmaceuticals Corp.: 2019 Oct.33718 - Intelence (etravirine) package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc.; 2019 July.33925 - Ventolin HFA (albuterol sulfate) Inhalation Aerosol package insert. Research Triangle Park, NC: GlaxoSmithKline; 2008 Mar.34364 - Humphries TJ, Merritt GJ. Review article: drug interactions with agents used to treat acid-related diseases. Aliment Pharmacol Ther 1999;13:18-26.34389 - Xenazine (tetrabenazine) package insert. Deerfield, IL: Lundbeck, Inc.; 2017 Sep.34390 - Hamelin BA, Bouayad A, Drolet B, Gravel A, Turgeon J. In vitro characterization of cytochrome P450 2D6 inhibition by classic histamine H1 receptor antagonists. Drug Metab Dispos 1998; 26(6): 536-9.34457 - Masimirembwa CM, Hasler JA. Characterisation of praziquantel metabolism by rat liver microsomes using cytochrome P450 inhibitors. Biochem Pharmacol 1994;48:1779-83.34458 - Godawska-Matysik A, Kiec-Kononowicz K. Biotransformation of praziquantel by human cytochrome p450 3A4 (CYP 3A4). Acta Pol Pharm 2006;63:381-5.34459 - Ridtitid W, Ratsamemonthon K, Mahatthanatrakul W, et al. Pharmacokinetic interaction between ketoconazole and praziquantel in healthy volunteers. J Clin Pharm Ther 2007;32:585-93.34471 - Goldstein PE, Boom A, van Geffel J, et al. P-glycoprotein inhibition by glibenclamide and related compounds. Pflugers Arch 1999;437:652-60.34472 - Kirchheiner J, Roots I, Goldammer M, et al. Effect of genetic polymorphisms in cytochrome p450 (CYP) 2C9 and CYP2C8 on the pharmacokinetics of oral antidiabetic drugs: clinical relevance. Clin Pharmacokinet 2005;44:1209-25.34483 - Rapaflo (silodosin) package insert. Corona, CA: Watson Pharmaceuticals, Inc.; 2013 Jan.34489 - Wire MB, Shelton MJ, Studenberg S. Fosamprenavir clinical pharmacokinetics and drug interactions of the amprenavir prodrug. Clin Pharmacokinet 2006;45:137-68.34490 - Polli JW, Jarrett JL, Studenberg SD, et al. Role of P-glycoprotein on the CNS disposition of amprenavir (141W94), an HIV protease inhibitor. Pharm Res 1999;16:1206-12.34491 - Fung HB, Kirschenbaum HL, Hameed R. Amprenavir: a new human immunodeficiency virus type 1 protease inhibitor. Clin Ther 2000;22:549-72.34503 - Lau YY, Huang Y, Frassetto L, et al. Effect of OATP1B transporter inhibition on the pharmacokinetics of atorvastatin in healthy volunteers. Clin Pharmacol Ther 2007;81:194-201.34515 - Desta Z, Wu GM, Morocho AM, et al. The gastoprokinetic and antiemetic drug metoclopramide is a substrate and inhibitor of cytochrome P450 2D6. Drug Metab Dispos 2002;30:336-343.34522 - Akutsu T, Kobayashi K, Sakurada K, et al. Identification of human cytochrome p450 isozymes involved in diphenhydramine N-demethylation. Drug Metab Dispos 2007;35:72-8.34523 - Hamelin BA, Bouayad A, Methot J, et al. Significant interaction between the nonprescription antihistamine diphenhydramine and the CYP2D6 substrate metoprolol in healthy men with high or low CYP2D6 activity. Clin Pharmacol Ther 2000;67:466-477.34526 - Obradovic T, Dobson GG, Shingaki T, et al. Assessment of the first and second generation antihistamines brain penetration and role of P-glycoprotein. Pharm Res 2007;24:318-27.34527 - Cvetkovic M, Leake B, Fromm MF, et al. OATP and P-glycoprotein transporters mediate the cellular uptake and excretion of fexofenadine. Drug Metab Dispos 1999;27:866-71.34540 - Sunman JA, Hawke RL, LeCluyse EL, et al. Kupffer cell-mediated IL-2 suppression of CYP3A activity in human hepatocytes. Drug Metab Dispos 2004;32:359-363.34557 - Lee CG, Gottesman MM, Cardarelli CO. HIV-1 protease inhibitors are substrates for the MDR1 multidrug transporter. Biochemistry 1998;37:3594-601.34558 - Storch CH, Theile D, Lindenmaier H, et al. Comparison of inhibitory activity of anti-HIV drugs on P-glycoprotein. Biochem Pharmacol 2007;73:1573-81.34597 - Lu P. Mechanism-based inhibition of human liver microsomal cytochrome P450 1A2 by zileuton, a 5-lipoxygenase inhibitor. Drug Metab Dispos 2003; 31(11): 1352-60.34598 - Machinist JM, Mayer MD, Shet MS, et al. Identification of the human liver cytochrome P450 enzymes involved in the metabolism of zileuton (ABT-077) and its N-dehydroxylated metabolite, Abbott-66193. Drug Metab Dispos 1995;23:1163-74.34626 - Vimpat (lacosamide) package insert. Smyrna, GA: UCB, Inc.; 2020 Feb.34653 - Schinkel AH, Wagenaar E, Mol C, et al. P-glycoprotein in the blood-brain barrier of mice influences the brain penetration and pharmacological activity of many drugs. J Clin Invest 1996;97:2517-2524.34654 - Schinkel AH, Smit J, van Tellingen O, et al. Disruption of mouse mdr1a p-glycoprotein gene leads to a deficiency in the blood-brain barrier and to increased sensitivity to drugs. Cell 1994;491-502.34655 - Vinblastine package insert. Bedford, NH: Bedford Laboratories; 2001 Dec.34656 - Huang R, Murry D, Foster D, et al. Role of xenobiotic efflux transporters in resistance to vincristine. Biomed Pharmacother 2008;62:59-64.34660 - Ambudkar SV, Kimchi-Sarfaty C, Sauna ZE, et al. P-glycoprotein: from genomics to mechanism. Oncogene 2003;22:7468-7485.34711 - Washio T, Arisawa H, Kohsaka K, et al. Identification of human drug-metabolizing enzymes involved in the metabolism of SNI-2011. Biol Pharm Bull 2001;24:1263-6.34743 - Hesse LM, von Moltke LL, Shader RI, et al. Ritonavir, efavirenz, and nelfinavir inhibit CYP2B6 activity in vitro: potential drug interactions with bupropion. Drug Metab Dispos 2001;29:100-2.34744 - Hogeland GW, Swindells S, McNabb JC, et al. Lopinavir/ritonavir reduces bupropion plasma concentrations in healthy subjects. Clin Pharmacol Ther 2007;81:69-75.34745 - Kharasch ED, Mitchell D, Coles R, et al. Rapid clinical induction of hepatic cytochrome P4502B6 activity by ritonavir. Antimicrob Agents Chemother 2008;52:1663-9.34746 - Foisy MM, Yakiwchuk EM, Hughes CA. Induction effects of ritonavir: implications for drug interactions. Ann Pharmacother 2008l;42:1048-59.34760 - Liangpunsakul S, Kolwankar D, Pinto A, et al. Activity of CYP2E1 and CYP3A enzymes in adults with moderate alcohol consumption: a comparison with nonalcoholics. Hepatology 2005;41:1144-50.34761 - Lieber CS. Microsomal ethanol-oxidizing system (MEOS): the first 30 years (1968-1998) - a review. Alcohol Clin Exp Res 1999;23:991-1007.34762 - Oneta CM, Lieber CS, Li J, et al. Dynamics of cytochrome P4502E1 activity in man: induction by ethanol and disappearance during withdrawal phase. J Hepatol 2002;36:47 -52.34878 - Soriano V, Puoti M, Sulkowski M, et al. Care of patients coinfected with HIV and hepatitis C virus: 2007 updated recommendations from the HCV-HIV International Panel. AIDS 2007;21:1073-89.34883 - Promethazine and codeine oral solution package insert. Baudette, MN: ANI Pharmaceuticals, Inc.; 2018 Jun.34979 - Entocort EC (budesonide) capsules package insert. Wilmington, DE: AstraZeneca LP; 2020 July35401 - Coartem (artemether; lumefantrine) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2019 Aug.35591 - Cycloset (bromocriptine mesylate) package insert. Tiverton, RI: VeroScience LLC; 2020 Aug.35780 - Samsca (tolvaptan) package insert. Tokyo, Japan: Otsuka Pharmaceuticals Co., Ltd.; 2017 Jun.36008 - Somogyi AA, Menelaou A, Fullston SV. CYP3A4 mediates dextropropoxyphene N-demethylation to nordextropropoxyphene: human in vitro and in vivo studies and lack of CYP2D6 involvement. Xenobiotica 2004;34:875-87.36049 - Prandin (repaglinide) tablets package insert. Plainsboro, NJ: Novo Nordisk Inc.; 2019 Jan.36101 - Multaq (dronedarone) package insert. Bridgewater, NJ: Sanofi-aventis; 2014 Mar.36111 - Onglyza (saxagliptin) package insert. Princeton, NJ: Bristol-Myers Squibb Company; 2019 Jun.36114 - Colcrys (colchicine) package insert. Deerfield, IL: Takeda Pharmaceuticals America, Inc.; 2020 May.36146 - Fanapt (iloperidone) package insert. Rockville, MD: Vanda Pharmaceuticals, Inc.; 2017 Mar.36343 - Saphris (asenapine) package insert. St. Loius, MO: Forest Pharmaceuticals, Inc.; 2017 Mar.36451 - Neuvonen PJ, Niemi M, Backman JT. Drug interactions with lipid-lowering drugs: mechanisms and clinical relevance. Clin Pharmacol Ther 2006;80:565-81.36615 - Vibativ (telavancin) package insert. Nashville, TN: Cumberland Pharmaceuticals Inc.; 2020 July.36646 - Valturna (aliskiren; valsartan) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2012 Jan.37098 - Votrient (pazopanib) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2011 Oct.37292 - Istodax (romidepsin) package insert. Bedford, OH: Ben Venue Laboratories, Inc.; 2018 Nov.37294 - Hijazi Y, Boulieu R. Contribution of CYP3A4, CYP2B6, and CYP2C9 isoforms to N-demethylation of ketamine in human liver microsomes. Drug Metab Dispos 2002;30(7):853-858.37590 - Elewski B, Tavakkol A. Safety and tolerability of oral antifungal agents in the treatment of fungal nail disease: a proven reality. Ther Clin Risk Manag. 2005;1(4):299-306.38831 - Oleptro (trazodone hydrochloride) extended-release tablets package insert. Dublin, Ireland: Labopharm Europe Limited; 2014 Jul.39682 - Food and Drug Administration MedWatch. Ongoing safety review of high-dose Zocor (simvastatin) and increased risk of muscle injury. Retrieved March 19, 2010. Available on the World Wide Web at http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm205404.htm.39870 - Niemi M. Role of OATP transporters in the disposition of drugs. Pharmacogenomics 2007;8:787-802.39926 - OxyContin (oxycodone HCl extended-release) package insert. Stamford, CT: Purdue Pharma L.P.; 2019 Oct.40025 - Verelan PM (verapamil hydrochloride extended-release capsules) package insert. Gainesville GA: Recro Technology LLC;2016 Nov.40027 - Emend (fosaprepitant dimeglumine injection) package insert. Whitehouse Station, NJ: Merck & Co.,Inc.; 2019 Nov.40029 - Dexilant (dexlansoprazole) package insert. Deerfield, IL: Takeda Pharmaceuticals America, Inc.; 2020 Sept.40233 - Sporanox (itraconazole) oral solution package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc.; 2019 Mar.40255 - Rybix ODT (tramadol) package insert. San Diego, CA: Victory Pharma, Inc.; 2009 Dec.40259 - Adcirca (tadalafil) package insert. Indianapolis, IN: Eli Lilly and Company; 2020 Sept.40337 - Aciphex (rabeprazole) delayed-release tablets package insert. Woodcliff Lake, NJ: Eisai Inc.; 2018 June.40360 - Flovent Diskus (fluticasone) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2017 July.40392 - Promacta (eltrombopag) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2020 Apr.40475 - Flovent Diskus (fluticasone) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2019 Jan.40596 - Prevacid (lansoprazole) capsules, tablets package insert. Deerfield, IL: Takeda Pharmaceuticals America, Inc.; 2020 Sept.40936 - Invega Sustenna (paliperidone palmitate injectable suspension) package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc.; 2019 Jan.40942 - Remeron and RemeronSolTabs (mirtazapine tablets and ODT tablets) package insert. Roseland, NJ: Organon USA, Inc.; 2020 Apr.40943 - Onsolis (fentanyl buccal soluble film) package insert. Raleigh, NC: BioDelivery Sciences, International, Inc.; 2019 Oct.40951 - MS Contin (morphine sulfate extended-release tablets) package insert. Stamford, CT: Purdue Pharma L.P.; 2019 Oct.40981 - Jevtana (cabazitaxel) package insert. Bridgewater, NJ: Sanofi-Aventis U.S. LLC; 2020 Feb.41124 - Staxyn (vardenafil orally disintegrating tablets) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2017 Aug.41231 - Foradil inhalation powder (formoterol fumarate) package insert. Kenilworth, NJ: Schering Corporation; 2012 Nov.41235 - Butrans (buprenorphine transdermal system) package insert. Stamford, CT: Purdue Pharma L.P.; 2019 Oct.41237 - Tegretol (carbamazepine) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2018 Mar.41243 - Provigil (modafinil) package insert. Frazer, PA: Cephalon; 2015 Jan.41275 - Sipe BE, Jones RJ, Bokhart GH, et al. Rhabdomyolysis causing AV blockade due to possible atorvastatin, esomeprazole, and clarithromycin interaction. Ann Pharmacother 2003;37:808-11.41276 - Blume H, Donath F, Warnke A, et al. Pharmacokinetic drug interaction profiles of proton pump inhibitors. Drug Saf 2006;29:769-84.41543 - Halcion (triazolam) package insert. New York, NY: Pharmacia and Upjohn Company; 2019 Oct.41569 - Ella (ulipristal 30 mg tablets) package insert. Paris, France: Laboratoire HRA Pharma; 2018 May.41597 - Implanon (etonogestrel) package insert. Whitehouse Station, NJ: Merck & Co., Inc.; 2017 March.41666 - Suboxone (buprenorphine; naloxone) sublingual film package insert. North Chesterfield, VA: Indivior Inc; 2019 Oct.41806 - Plaquenil (hydroxychloroquine) package insert. St. Michael, Barbados: Concordia Pharmaceuticals, Inc.; 2017 Jan.41823 - Gilenya (fingolimod) package insert. East Hanover, New Jersey: Novartis Pharmaceuticals Corporation; 2019 Dec.41830 - Corvert (ibutilide) package insert. New York, NY: Pharmacia and Upjohn Company; 2016 Aug.41934 - Lysodren (mitotane) package insert. Princeton, NJ: Bristol-Myers Squibb Oncology; 2017 May.41958 - Eloxatin (oxaliplatin) package insert. Bridgewater, NJ: Sanofi-aventis U.S. LLC; 2020 April.41984 - Primaquine phosphate package insert. Bridgewater, NJ: Sanofi-aventis; 2017 Jun.42121 - Pradaxa (dabigatran) package insert. Ridgefield, CT: Boehringer Ingelheim Pharmaceuticals, Inc.; 2020 Jul.42135 - Adams IB, Martin BR: Cannabis: pharmacology and toxicology in animals and humans. Addiction 1996;91(11):1585-1614.42227 - Latuda (lurasidone) package insert. Marlborough, MA: Sunovion Pharmaceuticals, Inc.; 2019 Dec.42280 - Nuedexta (dextromethorphan hydrobromide; quinidine sulfate capsule) package insert. Aliso Viejo, CA: Avanir Pharmaceuticals, Inc.; 2019 Jun.42290 - Zemplar (paricalcitol) capsule package insert. North Chicago, IL: AbbVie Inc.; 2018 Feb.42294 - Grotenhermen F. Pharmacokinetics and pharmacodynamics of cannabinoids. Clin Pharmacokinet 2003;42(4):327-360.42405 - Egrifta (tesamorelin) package insert. Montreal, Quebec: Theratechnologies, Inc.; 2019 Jul.42448 - Watanabe K, Yamaori S, Funahashi T, et al: Cytochrome P450 enzymes involved in the metabolism of tetrahydrocannabinols and cannabinol by human hepatic microsomes. Life Sciences 2007;80:1415-1419.42449 - Halaven (eribulin mesylate) injection package insert. Woodcliffe Lake, NJ: Eisai Inc.; 2016 Oct.42452 - Panel on Antiretroviral Therapy and Medical Management of HIV-infected Children. Guidelines for the use of antiretroviral agents in pediatric HIV infection. Available at https://files.aidsinfo.nih.gov/contentfiles/lvguidelines/PediatricGuidelines.pdf. Accessed May 11, 2020.42844 - FDA Drug Safety Communication: Abnormal heart rhythms associated with use of Anzemet (dolasetron mesylate). Retrieved December 17, 2010. Available on the World Wide Web at: http://www.fda.gov/Drugs/DrugSafety/ucm237081.htm.42845 - Abilify (aripiprazole) tablets, discmelt orally-disintegrating tablets, oral solution, and intramuscular injection package insert. Tokyo, Japan: Otsuka America Pharmaceutical, Inc.; 2020 Mar.42997 - Le Corre P, Parmer RJ, Kailasam MT, et al: Human sympathetic activation by alpha2-adrenergic blockade with yohimbine: Bimodal, epistatic influence of cytochrome P450-mediated drug metabolism. Clin Pharmacol Ther 2004;76(2):139-153.43065 - Chlorpromazine package insert. Princeton, NJ: Sandoz Inc; 2019 Dec.43069 - Thioridazine package insert. Philadelphia, PA:Mutual Pharmaceutical Company, Inc;2010 Sept.43177 - Viibryd (vilazodone) tablets package insert. Madison, NJ; Allergan USA, Inc.: 2018 May.43258 - Eryped (erythromycin ethylsuccinate) package insert. Atlanta, GA: Arbor Pharmaceuticals, INC.; 2018 Apr.43295 - Detrol LA (tolterodine extended-release capsules) package insert. New York, NY: Pharmacia and Upjohn Co., division of Pfizer; 2018 July.43411 - Cipro (ciprofloxacin tablet; suspension) package insert. Wayne, NJ: Bayer HealthCare Pharmaceuticals Inc.; 2020 May.43463 - Orap (pimozide) package insert. Sellersville, PA: Teva Pharmaceuticals USA; 2014 Mar.43551 - Daliresp (roflumilast) package insert. Wilmington, DE: AstraZeneca Pharmaceuticals, LP; 2018 Jan.43566 - Intuniv (guanfacine) package insert. Lexington, MA: Shire US Inc.; 2019 Dec.43800 - Lupron Depot (leuprolide acetate for depot suspension) package insert. North Chicago, IL: AbbVie Inc; 2017 July.43856 - Antivert (meclizine) package insert. East Brunswick, NJ: Casper Pharma LLC; 2019 Jun.43880 - Lamisil (terbinafine oral granules) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2019 Mar.43881 - Lamisil (terbinafine tablet) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2019 Mar.43900 - Lipitor (atorvastatin calcium) package insert. NY, NY: Parke-Davis Division of Pfizer; 2012 Feb.43901 - Caprelsa (vandetanib) package insert. Wilmington, DE: AstraZeneca Pharmaceuticals LP; 2020 June.43972 - Flovent HFA (fluticasone) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2019 Jan.43974 - Zithromax (azithromycin injection) package insert. New York, NY: Pfizer Inc.; 2019 Apr.44095 - Aplenzin (bupropion extended-release tablet) package insert. Bridgewater, NJ: Sanofi-aventis, LLC.; 2020 May.44314 - Victrelis (boceprevir) capsule package insert. Whitehouse Station, NJ: Merck and Co, Inc; 2017 Jan.44376 - Edurant (rilpivirine) package insert. Titusville, NJ: Janssen Therapeutics; 2019 May.44393 - Incivek (telaprevir) tablet package insert. Cambridge, MA: Vertex Pharmaceuticals, Inc; 2013 Oct.44800 - Potiga (ezogabine) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2016 May.44854 - Xarelto (rivaroxaban) package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc.; 2020 Mar44859 - Midazolam injection package insert. Lake Forest, IL: Hospira, Inc.; 2018 Aug.44951 - Brilinta (ticagrelor) package insert. Wilmington, DE: AstraZeneca Pharmaceuticals LP; 2020 Sept.44979 - Arcapta Neohaler (indacaterol inhalation powder) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2019 May.44982 - Cleocin (clindamycin capsules) package insert. New York, NY: Pharmacia and Upjohn Co; 2020 Feb.45335 - Zelboraf (vemurafenib) tablet package insert. South San Francisco, CA: Genentech USA, Inc.; 2020 May.45378 - Adcetris (brentuximab vedotin) package insert. Bothell, WA: Seattle Genetics, Inc.; 2019 Oct.45411 - Trelstar (triptorelin pamoate for injectable suspension) package insert. Parsipanny, NJ: Watson Pharma, Inc; 2018 Dec.45458 - Xalkori (crizotinib) package insert. New York, NY: Pfizer Labs; 2019 June.45527 - Lescol/Lescol XL (fluvastatin capsules/ fluvastatin sodium extended-release tablets) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2017 Aug.45644 - Starlix (nateglinide) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation.; 2018 May.45935 - Gefitinib (Iressa) package insert. Wilmington, DE: AstraZeneca Pharmaceuticals LP; 2018 Aug.46322 - Hycamtin (topotecan hydrochloride) for Injection package insert. Research Triangle Park, NC: GlaxoSmithKline; 2018 Sept.46370 - Onfi (clobazam tablets) package insert. Deerfield, IL: Lundbeck Inc.; 2018 Jun.46375 - Nexplanon (etonogestrel) package insert. Whitehouse Station, NJ: Merck & Co., Inc.; 2018 Oct.46638 - Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the use of antiretroviral agents in adults and adolescents with HIV. Department of Health and Human Services. Available at https://aidsinfo.nih.gov/guidelines. Accessed Dec 19, 2019.46782 - Jakafi (ruxolitinib) tablets package insert. Wilmington, DE: Incyte Corporation; 2020 Jan.46869 - Firmagon (degarelix) package insert. Parsippany, NJ: Ferring Pharmaceuticals Inc.; 2020 Dec.47129 - Hydroxyzine hydrochloride injection package insert. Shirley, NY: American Regent, Inc.; 2016 Oct.47165 - Norvir (ritonavir tablets, solution, and powder) package insert. North Chicago, IL: AbbVie Inc; 2019 Dec.47221 - Propulsid (cisapride) package insert. Titusville, NJ; Janssen Pharmaceutica; 2006 Oct. NOTE: As of May 2000; Propulsid has only been available in the United States via an investigational limited access program to ensure proper patient screening and prescribing.47357 - Quinidine gluconate extended-release tablet package insert. Richmond, VA: Richmond Pharmaceuticals, Inc.; 2017 Feb.48494 - Inlyta (axitinib) package insert. New York, NY: Pfizer Inc; 2020 June.48524 - Kalydeco (ivacaftor) package insert. Boston, MA: Vertex Pharmaceuticals Incorporated; 2019 April.48545 - Antabuse (disulfiram) tablet package insert. Pomona, NY: Duramed Pharmaceuticals, Inc.; 2010 Feb.48576 - Tindamax (tinidazole tablets) package insert. Tulsa, OK: Physicians Total Care; 2010 Aug.48617 - Evoxac (cevimeline) package insert. Edison, NJ: Daiichi Sankyo Pharma Development; 2018 April.48620 - Pletal (cilostazol) package insert. Rockville, MD: Otsuka America Pharmaceutical, Inc.; 2017 May.48674 - FDA Drug Safety Communication. Victrelis (boceprevir) and ritonavir-boosted human immunodeficiency virus (HIV) protease inhibitor drugs: drug safety communication - drug interactions. Retrieved February 9, 2012. http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm291144.htm?source=govdelivery48697 - Korlym (mifepristone) tablet package insert. Menlo Park, CA: Corcept Therapeutics Incorporated; 2017 May.48961 - Vasilev NP, Julsing MK, Koulman A, et al. Bioconversion of deoxpodophyllotoxin into epipodophyllotoxin in E. coli using human cytochrome P450 3A4. J Biotechnol 2006;126:383—93.49123 - Vincasar PFS (vincristine) package insert. Irvine, CA: Teva Parenteral Medicines, Inc.; 2014 Aug.49493 - Hectorol (doxercalciferol) injection package insert. Cambridge, MA: Genzyme Corporation; 2016 Jun.49598 - Zortress (everolimus) package insert. East Hanover, NJ: Novartis Pharmaceutical Corporation; 2010 Apr.49806 - Taxol (paclitaxel) prescribing information. Bristol Myers Squibb: Princeton, NJ; 2011 Apr.49823 - Afinitor (everolimus) tablets package insert. East Hanover, NJ:Novartis Pharmaceuticals Corporation; 2020 Feb.49866 - Stendra (avanafil) package insert. Mountain View, CA: VIVUS, Inc.; 2018 Aug.50113 - Lee EC, Walmsley S, Fantus IG. New-onset diabetes mellitus associated with protease inhibitor therapy in an HIV-positive patient: case report and review. CMAJ. 1999;161(2):161-164.50341 - Cardene SR (nicardipine) package insert. Bedminster, NJ: EKR Therapeutics, Inc.; 2016 Aug.50507 - Luvox CR (fluvoxamine maleate extended-release capsules) package insert. Palo Alto, CA: Jazz Pharmaceuticals, Inc.; 2017 Jan.50586 - Torisel (temsirolimus) injection package insert. Philadelphia, PA: Wyeth Pharmaceuticals Inc; 2018 March.50623 - Ulipristal (Esmya 5 mg tablets) European package insert. London UK; Gedeon Richter (UK) Ltd: 2017 Aug.50768 - Lexiva (fosamprenavir calcium) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2008 Mar.50769 - Invirase (saquinavir) package insert. South San Francisco, CA: Genentech Inc.; 2016 Sept.50814 - Carr A, Miller J, Samaras K, Burton S. A syndrome of peripheral lipodystrophy, hyperlipidaemia and insulin resistance in patients receiving HIV protease inhibitors. AIDS. 1998;12(7):F51-F58.51027 - Ifex (ifosfamide) package insert. Deerfield, IL: Baxter Healthcare Corp; 2018 Jul51080 - Kaletra (lopinavir; ritonavir) capsule package insert. North Chicago, IL: AbbVie Inc; 2019 Aug.51111 - Myrbetriq (mirabegron) package insert. Northbrook, Illinois: Astellas Pharma US, Inc.; 2018 April.51119 - Zyflo (zileuton) immediate release tablets package insert. Cary, NC: Chiesi Inc.; 2017 Jan.51227 - Apidra (insulin glulisine [rDNA origin]) injection package insert. Bridgewater, NJ: Sanofi-Aventis US LLC; 2019 Nov.51289 - Inapsine (droperidol) package insert. Lake Forest, IL: Akorn, Inc.; 2011 Nov.51432 - Marqibo (vincristine sulfate liposome) injection package insert. East Windsor, NJ: Acrotech Biopharma LLC; 2020 June.51664 - Stribild (elvitegravir; cobicistat; emtricitabine; tenofovir disoproxil fumarate) package insert. Foster City, CA: Gilead Sciences, Inc; 2020 Aug.51727 - Xtandi (enzalutamide) capsule and tablet package insert. Northbrook, IL:Astellas Pharma US, Inc.; 2020 Aug.51739 - Bosulif (bosutinib) tablet package insert. Pfizer Labs:New York, NY; 2020 June.51834 - Food and Drug Administration (FDA): Drug development and drug interactions. Retrieved Sep 19, 2012. Available on the World Wide Web http://www.fda.gov/Drugs/DevelopmentApprovalProcess/DevelopmentResources/DrugInteractionsLabeling/ucm093664.htm#transporter.51883 - Stivarga (regorafenib) tablet package insert. Wayne, NJ: Bayer HealthCare Pharmaceuticals Inc.; 2020 July.52140 - Perampanel (Fycompa) tablets and oral suspension package insert. Woodcliff Lake, NJ: Eisai Inc.; 2019 May.52315 - Xeljanz and Xeljanz XR (tofacitinib) package insert. New York, NY: Pfizer, Inc.; 2019 Dec.52506 - Cometriq (Cabozantinib) capsules package insert. South San Francisco, CA:Exelixis, Inc.; 2020 Jan52603 - Iclusig (ponatinib) tablet package insert. Cambridge, MA: Takeda Pharmaceuticals Company Limited; 2020 Jan.52611 - Signifor (pasireotide diaspartate) package insert. Stein, Switzerland: Novartis Pharma Stein AG; 2020 Jan.52698 - Juxtapid (lomitapide) package insert. Cambridge, MA: Aegerion Pharmaceuticals, Inc.; 2019 Dec.52739 - Apixaban (Eliquis) package insert. Bristol-Myers Squibb Company; Princeton, NJ. 2019 Nov.52746 - Sirturo (bedaquiline) tablet package insert. Titusville, NJ: Janssen Therapeutics; 2020 May.53295 - Ado-trastuzumab emtansine (Kadcyla) Package Insert. San Francisco, CA: Genentech, Inc; 2019 May.53344 - Osphena (ospemifene) tablets package insert. Florham Park, N.J: Shionogi, Inc.; 2019 Jan.53394 - Abilify Maintena (aripiprazole) extended-release intramuscular injection package insert. Rockville, MD:Otsuka America Pharmaceutical, Inc.; 2020 Feb.53544 - Erythromycin delayed-release capsule package insert; Greenville, NC: Mayne Pharma; 2018 Apr53972 - Invokana (canagliflozin) package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc; 2020 Aug.54021 - Vesicare (solifenacin) package insert. Norman, OK: Astellas Pharma Technologies, Inc.; 2020 May.54578 - Clolar (clofarabine) injection package insert. Cambridge, MA: Genzyme Corporation; 2019 Dec.54634 - Owen JR, Nemeroff CB. New antidepressants and the cytochrome P450 system: focus on venlafaxine, nefazodone, and mirtazapine. Depress Anxiety 1998;7:24-32.54713 - VFEND (voriconazole) injection package insert. New York, NY: Pfizer Inc; 2014 Sept.54802 - Tafinlar (dabrafenib) capsules package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2020 Apr.55331 - Gilotrif (afatinib) tablets package insert. Ridgefield, CT: Boehringer Ingelheim Pharmaceuticals, Inc; 2019 Nov.55401 - Astagraf XL (tacrolimus extended-release capsules) package insert. Northbrook, IL: Astellas Pharma US, Inc.; 2018 Nov.55469 - Fetzima (levomilnacipran) extended-release capsules package insert. Madison, NJ: Allergan USA, Inc.; 2019 Oct.55578 - Owczuk R, Twardowski P, Dylczyk-Sommer A, et al. Influence of promethazine on cardiac repolarization: a double-blind, midazolam-controlled study. Anaesthesia 2009;64:609-614.55901 - Riss J, Cloyd J, Gates J, et al. Benzodiazepines in epilepsy: pharmacology and pharmacokinetics. Acta Neurol Scand. 2008;118:69-86.56074 - Duavee (conjugated estrogens and bazedoxifene) package insert. Philadelphia, PA: Wyeth Pharmaceuticals Inc.; 2019 Dec.56096 - Adempas (riociguat) package insert. Whippany, NJ: Bayer HealthCare Pharmaceuticals Inc.; 2018 Dec.56202 - Kenalog-10 (triamcinolone acetonide) injection package insert. Princeton, NJ: Bristol-Myers Squibb Company; 2018 Jun.56260 - Opsumit (macitentan) package insert. South San Francisco, CA: Actelion Pharmaceuticals US, Inc; 2019 Apr.56303 - Zohydro ER (hydrocodone extended-release capsules) package insert. Morristown, NJ: Currax Pharmaceuticals LLC; 2019 Oct.56361 - Doxorubicin hydrochloride package insert. New York, NY: Pfizer Labs; 2013 Oct.56410 - Imbruvica (ibrutinib) capsule package insert. Sunnyvale, CA: Pharmacyclics, Inc.; 2020 Aug.56436 - Aptiom (eslicarbazepine acetate) package insert. Marlborough, MA: Sunovion Pharmaceuticals Inc.; 2019 Mar.56471 - Olysio (simeprevir) capsule package insert. Titusville, NJ: Janssen Therapeutics; 2017 Nov.56538 - Vickers AE, Sinclair JR, Zollinger M. Multiple cytochrome P-450s involved in the metabolism of terbinafine suggest a limited potential for drug-drug interactions. Drug Metab Dispos. 1999;27(9):1029-1038.56565 - Wessler JD, Grip LT, Mendell J, et al. The P-glycoprotein transport system and cardiovascular drugs. J Am Coll Cardiol 2013;61:2495-502.56579 - Drug Development and Drug Interactions: Table of Substrates, Inhibitors and Inducers. Updated Mar 10, 2020. Retrieved from the World Wide Web at www.fda.gov/Drugs/DevelopmentApprovalProcess/DevelopmentResources/DrugInteractionsLabeling/ucm093664.htm56665 - Hetlioz (tasimelteon) package insert. Washington, D.C.: Vanda Pharmaceuticals, Inc.; 2019 Oct.56871 - Navelbine (vinorelbine) injection package insert. Parsippany, NJ: Pierre Fabre Pharmaceuticals Inc; 2020 Jan.57012 - Welage LS, Berardi RR. Drug interactions with anti-ulcer agents: considerations in the treatment of acid-peptic disease. J Pharm Pract. 1994;7:177-195.57036 - Brodie MJ, Mintzer S, Pack AM, et al. Enzyme induction with antiepileptic drugs: cause for concern? Epilepsia 2013;54:11-27.57037 - Lionetto L, Casolla B, Mastropietri F, et al. Pharmacokinetic evaluation of zolmitriptan for the treatment of migraines. Expert Opin Drug Metab Toxicol 2012;8:1043-50.57048 - Drug Development and Drug Interactions: Table of Substrates, Inhibitors and Inducers. Retrieved from the World Wide Web December 27, 2013. http://www.fda.gov/Drugs/DevelopmentApprovalProcess/DevelopmentResources/DrugInteractionsLabeling/ucm093664.htm#major57066 - Bharucha AE, Skaar T, Andrews CN, et al. Relationship of cytochrome P450 pharmacogenetics to the effects of yohimbine on gastrointestinal transit and catecholamines in healthy subjects. Neurogastroenterol Motil 2008;20: 891–9.57067 - Lindsey WT, Stewart D, Childress D. Drug interactions between common illicit drugs and prescription therapies. Am J Drug Alcohol Abuse 2012;38:334-43.57080 - de Leon J, Santoro V, D'Arrigo C, et al. Interactions between antiepileptics and second generation antipsychotics. Expert Opin Drug Metab Toxicol 2012;8:311-34.57084 - Zhou SF. Polymorphism of human cytochrome P450 2D6 and its clinical significance: part 1. Clin Pharmacokinet 2009;48:689-723.57094 - Zykadia (ceritinib) package insert. Indianapolis, IN: Novartis; 2019 March.57151 - Zontivity (vorapaxar) package insert. Parsippany, NJ: Aralez Pharmaceuticals US Inc.; 2019 Nov.57377 - Altin C, Kanyilmaz S, Baysal S, et al. QT interval prolongation due to metronidazole administration. Anadolu Kardiyol Derg 2011;11:46-9.57378 - Cohen O, Saar N, Swartzon M, et al. First report of metronidazole-induced QT interval prolongation. Int J Antimicrob Agents 2008;31:180-81.57441 - Iribarren C, Round AD, Peng JA, et al. Validation of a population-based method to assess drug-induced alterations in QT interval: a self-controlled crossover study. Pharmacoepidemiol Drug Saf 2013;22;1222-32.57648 - Depo-Provera (medroxyprogesterone acetate 400 mg/ml) injection suspension package insert. New York, NY: Pharmacia & Upjohn Company; 2017 Apr.57675 - Zydelig (idelalisib) tablet package insert. Foster City, CA:Gilead Sciences, Inc.; 2018 Oct.57710 - Striverdi Respimat (olodaterol) package insert. Ridgefield, CT: Boehringer Ingelheim Pharmaceuticals, Inc.; 2019 May.57741 - Orbactiv (oritavancin) package insert. Lincolnshire, IL: Melinta Therapeutics, Inc.; 2019 Dec.57780 - Belsomra (suvorexant) tablets package insert. Whitehouse Station, NJ: Merck Sharp & Dohme Corp.; 2020 Jan.57789 - Ambien (zolpidem immediate-release tablets) package insert. Bridgewater, NJ: Sanofi-Aventis U.S. LLC; 2019 Aug.57803 - Cerdelga (eliglustat) capsules. Waterford, Ireland: Genzyme Ireland, Ltd.;2018 Sept.57805 - Arnuity Ellipta (fluticasone) package insert. Research Triangle Park, NC: GlaxoSmithkline; 2019 Jan.57935 - Guidelines for prevention of opportunistic infections among hematopoietic stem cell transplant recipients: recommendations of CDC, the infectious disease society of america, and the american society of blood and marrow transplantation. Biol Blood Marrow Transpl. 2000;6:659-713.57937 - Movantik (naloxegol) package insert. Wilmington, DE: AstraZeneca Pharmaceuticals LP; 2020 April.57949 - Wils P, Phung-Ba V, Warnery A, et al. Polarized transport of docetaxel and vinblastine mediated by P-glycoprotein in human intestinal epithelial cell monolayers. Biochemical Pharmacology. 1994;48(7):1528-1530.58000 - Tybost (cobicistat) package insert. Foster City, CA: Gilead Sciences, Inc; 2020 Aug.58001 - Vitekta (elvitegravir) package insert. Foster City, CA: Gilead Sciences, Inc; 2015 Jul.58167 - Harvoni (ledipasvir; sofosbuvir) tablet and oral pellets package insert. Foster City, CA: Gilead Sciences, Inc; 2020 Mar.58171 - Akynzeo (fosnetupitant; palonosetron) package insert. Lugano, Switzerland: Helsinn Healthcare; 2020 May58189 - Esbriet (pirfenidone) capsules and film-coated tablets package insert. South San Fransisco, CA: Genentech USA, Inc.; 2019 July.58203 - Ofev (nintedanib) capsule package insert. Ridgefield, CT: Boehringer Ingelheim Pharmaceuticals, Inc; 2020 Mar.58531 - Hysingla ER (hydrocodone) extended release tablets package insert. Stamford, CT: Purdue Pharma L.P.; 2019 Oct.58620 - Asmanex HFA (mometasone furoate inhalation aerosol) package insert. Whitehouse Station, NJ: Merck & Co., Inc.: 2019 Aug.58662 - Lynparza (olaparib) tablets package insert. Wilmington, DE: AstraZeneca Pharmaceuticals LP; 2020 May.58664 - Viekira Pak (ombitasvir; paritaprevir; ritonavir; dasabuvir) tablet package insert. North Chicago, IL: AbbVie, Inc; 2019 Dec.58679 - Atrio J, Stanczyk FZ, Neely M, et al. Effect of protease inhibitors on steady-state pharmacokinetics of oral norethindrone contraception in HIV-infected women. J Acquir Immune Defic Syndr. 2014;65:72-77.58685 - Savaysa (edoxaban) package insert. Basking Ridge, NJ: Daiichi Sankyo, Inc.; 2020 Apr.58761 - Evotaz (atazanavir and cobicistat) tablet package insert. Princeton, NJ: Bristol-Myers Squibb Company; 2020 July.58763 - Prezcobix (darunavir and cobicistat) tablets package insert. Titusville, NJ: Janssen Therapeutics; 2020 July.58766 - Tasigna (nilotinib) capsules package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2019 Sept.58768 - Ibrance (palbociclib) capsules package insert. New York, NY: Pfizer Inc; 2019 Sept.58782 - Lenvima (lenvatinib) package insert. Woodcliff Lake, NJ:Eisai Inc; 2020 Sept.58821 - Farydak (panobinostat) capsules package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2016 June.58864 - Catley L, Weisberg E, Kiziltepe T, et al. Aggresome induction by proteasome inhibitor bortezomib and alpha-tubulin hyperacetylation by tubulin deacetylase (TDAC) inhibitor LBH589 are synergistic in myeloma cells. Blood 2006;108(10):3441-3449.59042 - Cresemba (isavuconazonium) package insert. Northbrook, IL: Astellas Pharma US, Inc; 2019 Dec.59321 - CredibleMeds. QT drug lists. Available on the World Wide Web at http://www.crediblemeds.org.59322 - Howes LG. Cardiovascular effects of drugs used to treat alzheimer's disease. Drug Saf. 2014;37:391–395.59430 - Corlanor (ivabradine) package insert. Thousand Oaks, CA: Amgen Inc.; 2019 Apr.59487 - Pomalyst (pomalidomide) capsules package insert. Summit, NJ: Celgene Corporation; 2020 May.59581 - Vinorelbine package insert. Lake Forest, IL: Hospira, Inc; 2015 Jan.59741 - Viberzi (eluxadoline) package insert. Parsippany, NJ: Actavis Pharma, Inc.; 2020 June.59809 - Mamiya K, Sadanaga T, Sekita A, et al. Lithium concentration correlates with QTc in patients with psychosis. J Electrocardiol 2005;38:148-51.59810 - van Noord C, Straus SM, Sturkenboom MC, et al. Psychotropic drugs associated with corrected QT interval prolongation. J Clin Psychopharmacol 2009;29:9-15.59811 - Altinbas K, Guloksuz S, Caglar IM, et al. Electrocardiography changes in bipolar patients during long-term lithium monotherapy. Gen Hosp Psychiatry 2014;36:694-7.59891 - Orkambi (lumacaftor; ivacaftor) tablet package insert. Boston, MA: Vertex Pharmaceuticals, Inc. 2018 August59949 - Rexulti (brexpiprazole) tablets package insert. Rockville, MD: Otsuka Pharmaceutical Co., Ltd.; 2020 Jun.60000 - Odomzo (sonidegib) capsules package insert. Cranbury, NJ: Sun Pharmaceutical Industries, Inc.; 2017 Sept.60001 - Daklinza (daclatasvir) package insert. Princeton, NJ: Bristol-Myers Squibb Company; 2019 Oct.60002 - Technivie (ombitasvir; paritaprevir; ritonavir) tablet package insert. North Chicago, IL: AbbVie, Inc; 2019 Dec.60087 - Sprycel (dasatinib) tablet package insert. Princeton, NJ Bristol-Myers Squibb Company; 2018 Dec.60099 - Addyi (flibanserin tablets) package insert. Raleigh, NC: Sprout Pharmaceuticals, Inc.; 2019 Aug.60164 - Vraylar (cariprazine capsules) package insert. Parsippany, NJ:Actavis Pharma, Inc.; 2019 May.60172 - Tresiba (insulin degludec) injection package insert. Plainsboro, NJ: Novo Nordisk Inc.; 2019 Nov.60196 - Aristada (aripiprazole lauroxil) extended-release intramuscular suspension package insert. Waltham, MA: Alkermes, Inc.; 2020 Feb.60248 - Yondelis (trabectedin) injection package insert. Horsham, PA: Janssen Products, LP; 2018 July.60263 - Utibron Neohaler (indacaterol; glycopyrrolate) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2019 May.60269 - Genvoya (elvitegravir; cobicistat; emtricitabine; tenofovir alafenamide) package insert. Foster City, CA: Gilead Sciences, Inc; 2019 Feb.60270 - Belbuca (buprenorphine) buccal film package insert. BioDeliviery Sciences International, Inc.: Raleigh, NC; 2019 Oct.60281 - Cotellic (cobimetinib) tablets package insert. San Francisco, CA: Genentech USA, Inc; 2016 June.60297 - Tagrisso (osimertinib) tablet package insert. Wilmington, DE: AstraZeneca Pharmaceuticals LP; 2018 Aug.60472 - Uptravi (selexipag) package insert. South San Francisco, CA: Actelion Pharmaceuticals US, Inc.; 2019 Sept.60473 - Zurampic (lesinurad) tablets package insert. Wilmington, DE: AstraZeneca Pharmaceuticals LP; 2015 Dec.60484 - Taxotere (docetaxel) injection package insert. Bridgewater, NJ: Sanofi-Aventis U.S. LLC; 2020 May.60497 - Envarsus XR (tacrolimus) extended-release tablets. Cary, NC: Veloxis Pharmaceuticals, Inc.; 2020 Sept.60523 - Zepatier (elbasvir; grazoprevir) tablet package insert. Whitehouse Station, NJ: Merck, Inc; 2019 Dec.60706 - Venclexta (venetoclax) tablets package insert. South San Francisco, CA:Genentech USA, Inc.; 2019 July.60738 - Cabometyx (Cabozantinib) tablets package insert. Alameda, CA: Exelixis, Inc.; 2020 July.60748 - Nuplazid (pimavanserin) package insert. San Diego, CA: Acadia; 2019 Sep.60845 - Gutmann H, Fricker G, Drewe J, et al. Interactions of HIV protease inhibitors with ATP-dependent drug export proteins. Mol Pharmacol. 1999;56:383-389.60860 - Byvalson (nebivolol and valsartan) tablets package insert. Parsippany, NJ: Actavis Pharma, Inc.; 2016 Jun.60864 - US Food and Drug Administration (FDA). FDA Drug Safety Communication: FDA warns about serious heart problems with high doses of the antidiarrheal medicine loperamide (Imodium), including from abuse and misuse. Retrieved June 7, 2016. Available on the World Wide Web at: http://www.fda.gov/Drugs/DrugSafety/ucm504617.htm?source=govdelivery&utm_medium=email&utm_source=govdelivery60895 - Calcifediol (Rayaldee) extended-release capsules package insert. Miami, FL: Opko Pharmaceuticals, LLC; 2019 Dec.60951 - Syndros (dronabinol) oral solution package insert. Chandler, AZ; Insys Therapeutics, Inc. 2018 Sept.61147 - Mitigare (colchicine) capsules package insert. Eatontown, NJ: West-Ward Pharmaceuticals Corp; 2015 Nov.61510 - Kiser JJ, Gerber JG, Predhomme JA, et al. Drug/Drug interaction between lopinavir/ritonavir and rosuvastatin in healthy volunteers. J Acquir Immune Defic Syndr. 2008;47:570-57861511 - Karlgren M, Ahlin G, Bergstrom CA, et al. In Vitro and In Silico strategies to identify OATP1B1 inhibitors and predict clinical drug-drug interactions. Pharm Res. 2012;29:411-42661512 - Busti AJ, Bain AM, Hall RG, et al. Effects of atazanavir/ritonavir or fosamprenavir/ritonavir on the pharmacokinetics of rosuvastin. J Cardiovasc Pharmacol. 2008;51:605-61061513 - Annaert P, Ye ZW, Stieger B, et al. Interaction of HIV protease inhibitors with OATP1B1, 1B3, and 2B1. Xenobiotica. 2010;40(3):163-17661590 - Targretin (bexarotene) capsules package insert. Bridgewater, NJ: Valeant Pharmaceuticals North America LLC; 2016 June.61718 - Tepadina (thiotepa) injection package insert. Bridgewater, NJ: Amneal Biosciences LLC; 2017 May.61750 - Emflaza (deflazacort) tablets and oral suspension. South Plainfield, NJ: PTC Therapeutics; 2020 Jul.61795 - Xermelo (telotristat ethyl) package insert. The Woodlands, TX: Lexicon Pharmaceuticals, Inc; 2017 Feb.61816 - Kisqali (ribociclib) tablets package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2020 July.61831 - Symproic (naldemedine) package insert. Florham Park, NJ: Shionogi, Inc.; 2018 Jan.61845 - Austedo (deutetrabenazine) tablets package insert. North Wales, PA: Teva Pharmaceuticals USA, Inc.; 2019 Jul.61870 - Chiu MH, Al-Majed NS, Stubbins R, et al. A case report of QT prolongation with glycopyrronium bromide in a patient with chronic tamoxifen use. BMC Res Notes. 2016;9:310.61871 - Slovacek L, Priester P, Petera J, et al. Tamoxifen/norfloxacin interaction leading to QT interval prolongation in a female patient with extracranial meningioma. Bratisl Lek Listy. 2011;112(6):353-4.61872 - Slovacek L, Ansorgova V, Macingova Z, et al. Tamoxifen-induced QT interval prolongation. J Clin Pharm Ther. 2008;33(4):453-5.61873 - Ingrezza (valbenazine) capsules package insert. San Diego, CA: Neurocrine Biosciences, Inc.; 2020 Apr.61906 - Rydapt (midostaurin) capsule package insert. East Hanover,NJ: Novartis Pharmaceuticals Corporation; 2020 Mar.61909 - Alunbrig (brigatinib) tablet package insert. Cambridge, MA: Ariad Pharmaceuticals Inc.; 2020 May.61924 - Gorski JC, Huang SM, Pinto AP, et al. The effect of echinacea (Echinacea purpurea root) on cytochrome P450 activity in vivo. Clin Pharmacol Ther. 2004;75:89-100.61926 - Penzak SR, Robertson SM, Hunt JD, et al. Echinacea purpurea significantly induces cytochrome P450 3A activity but does not alter lopinavir-ritonavir exposure in healthy subjects. Pharmacotherapy. 2010;30:797-805.61927 - Molto J, Valle M, Miranda C, et al. Herb-drug interaction between Echinacea purpurea and darunavir-ritonavir in HIV-infected patients. Antimicrob Agents Chemother. 2011;55:326-330. Epub 2010 Nov 15.62037 - Bevyxxa (betrixaban) capsules package insert. South San Francisco, Ca: Portola Pharmaceuticals, Inc.; 2020 Aug.62127 - Nerlynx (neratinib) package insert. Los Angeles, CA: Puma Biotechnology, Inc; 2020 July.62131 - Vosevi (sofosbuvir; velpatasvir; voxilaprevir) tablet package insert. Foster City, CA: Gilead Sciences, Inc; 2019 Nov.62201 - Mavyret (glecaprevir; pibrentasvir) tablets package insert. North Chicago, IL: AbbVie Inc.; 2020 Apr.62245 - Besponsa (inotuzumab ozogamicin) injection package insert. Philadelphia, PA: Wyeth Pharmaceuticals Inc; 2017 Aug.62292 - Mylotarg (gemtuzumab ozogamicin) injection package insert. Philadelphia, PA: Pfizer Inc.; 2020 Feb.62347 - Aliqopa (copanlisib) injection package insert. Whippany, NJ: Bayer HealthCare Pharmaceuticals Inc.; 2020 Feb.62393 - Verzenio (abemaciclib) tablets package insert. Indianapolis, IN: Lilly USA, LLC; 2020 March62578 - Calquence (acalabrutinib) capsules package insert. Wilmington, DE: AstraZeneca Pharmaceuticals LP; 2019 Nov.62611 - Prevymis (letermovir) package insert. Whitehouse Station, NJ: Merck and Co, Inc.; 2020 Mar.62723 - Macrilen (macimorelin) package insert. Frankfurt am Main, Germany: Aeterna Zentaris GmbH; 2018 Jan.62870 - Symdeko (tezacaftor; ivacaftor and ivacaftor tablets) package insert. Boston, MA; Vertex Pharmaceuticals Incorporated: 2019 Dec.62874 - Erleada (apalutamide) tablets package insert. Horsham, PA: Janssen Products, LP; 2020 Sept.62889 - Apadaz (benzhydrocodone; acetaminophen) tablets package insert. Newton, PA: KVK-Tech, Inc.; 2019 Oct.63066 - Celestone Soluspan (Betamethasone sodium phosphate and betamethasone acetate injection package insert). Whitehouse Station, NJ: Merck & Co., Inc.; 2018 April.63084 - Tavalisse (fostamatinib disodium hexahydrate) tablets package insert. South San Francisco, CA: Rigel Pharmaceuticals, Inc.; 2018 Apr.63106 - Jynarque (tolvaptan) tablets package insert. Rockville, MD: Otsuka America Pharmaceutical, Inc.; 2020 Jan.63161 - Lucemyra (lofexidine) tablets package insert. Louisville, KY: US WorldMeds, LLC; 2018 May.63168 - Sun X, Li J, Guo C, et al. Pharmacokinetic effects of curcumin on docetaxel mediated by OATP1B1, OATP1B3 and CYP450s. Drug Metab Pharmacokinet. 2016;31:269-75.63175 - Doptelet (avatrombopag) tablets package insert. Durham, NC: Dova Pharmaceuticals, Inc.; 2020 Aug.63317 - Braftovi (encorafenib) capsules package insert. Boulder, CO: Array BioPharma Inc.; 2020 April.63328 - Aristada Initio (aripiprazole lauroxil extended-release injectable suspension) package insert. Altham, MA:Alkermes, Inc.; 2020 Feb.63368 - Tibsovo (ivosidenib) tablet package insert. Cambridge, MA: Agios Pharmaceuticals; 2019 May.63387 - Orilissa (elagolix) tablets package insert. North Chicago, IL: AbbVie Inc.; 2019 Aug.63411 - Perseris (risperidone extended-release subcutaneous injectable suspension) package insert. North Chesterfield, VA: Indivior, Inc.; 2018 Dec.63429 - Annovera (segesterone acetate and ethinyl estradiol vaginal ring) package insert. New York, NY: Population Council; 2018 Aug.63484 - Pifeltro (doravirine) package insert. Whitehouse Station, NJ: Merck & Co., Inc.; 2019 Oct.63571 - Copiktra (duvelisib) capsules package insert. Needham, MA: Verastem, Inc.; 2018 Sept.63589 - Soltamox (tamoxifen) oral solution package insert. Raleigh, NC: Midatech Pharma US Inc.; 2019 April.63651 - Talzenna (talazoparib) capsules package insert. New York, NY: Pfizer Labs; 2020 Feb.63694 - Bijuva (estradiol; progesterone) capsules package insert. Boca Raton, FL: TherapeuticsMD, Inc.; 2019 Nov.63731 - Dsuvia (sufentanil) sublingual tablets package insert. Redwood City, CA: AcelRx Pharmaceuticals, Inc.; 2019 Oct.63732 - Lorbrena (lorlatinib) tablets package insert. New York, NY: Pfizer Labs; 2018 Nov.63742 - Yupelri (revefenacin) package insert. Morgantown, WV: Mylan Specialty L.P. 2019 May.63777 - Daurismo (glasdegib) tablets package insert. New York, NY: Pfizer Labs; 2020 Mar.63780 - Vitrakvi (larotrectinib) capsules and oral solution package insert. Stamford, CT: Loxo Oncology, Inc.; 2018 Nov.63787 - Xospata (gilteritinib) tablets package insert. Northbrook, IL: Astellas Pharma US, Inc.; 2019 May.63936 - Lamprene (clofazimine) package insert. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2019 Jan.63962 - Egaten (triclabendazole) package insert. East Hanover, NJ: Novartis Pharmaceuticals; 2019 Feb.64031 - Mayzent (siponimod) tablets package insert. East Hanover, NJ: Novartis Pharmaceutical Corporation; 2019 Mar.64064 - Balversa (erdafitinib) tablets package insert. Horsham, PA: Janssen Products, LP; 2019 April.64290 - Polivy (polatuzumab vedotin-piiq) injection package insert. South San Francisco, CA: Genentech, Inc.; 2019 June.64391 - Beach SR, Kostis WJ, Celano CM, et al. Meta-analysis of selective serotonin reuptake inhibitor-associated QTc prolongation. J Clin Psychiatry 2014;75:e441-e449.64392 - Glassman AH, O'Connor CM, Califf RM, et al. Sertraline treatment of major depression in patients with acute MI or unstable angina. JAMA 2002;288:701-709.64394 - O'Connor CM, Jiang W, Kuchibhatla M, et al. Safety and efficacy of sertraline for depression in patients with heart failure: results of the SADHART-CHF (Sertraline Against Depression and Heart Disease in Chronic Heart Failure) trial. J Am Coll Cardiol 2010;56:692-699.64395 - Brouillette J, Nattel S. A practical approach to avoiding cardiovascular adverse effects of psychoactive medications. Can J Cardiol 2017;33:1577-1586.64396 - Beach SR, Celano CM, Sugrue AM, et al. QT prolongation, torsades de pointes, and psychotropic medications: a 5-year update. Psychosomatics 2018;59:105-122.64525 - Nubeqa (darolutamide) tablets package insert. Whippany, NJ: Bayer HealthCare Pharmaceuticals Inc; 2019 July.64535 - Turalio (pexidartinib) capsules package insert. Basking Ridge, NJ: Daiichi Sankyo, Inc.; 2020 Apr.64562 - Wakix (pitolisant) tablets package insert. Plymouth Meeting, PA: Harmony Biosciences, LLC; 2019 Aug.64567 - Rozlytrek (entrectinib) package insert. South San Francisco, CA: Genentech Inc.; 2019 Aug.64568 - Inrebic (fedratinib) capsules package insert. Summit, NJ: Celgene Corporation; 2019 Aug.64572 - Rinvoq (upadacitinib) package insert. North Chicago, IL: Abbvie Inc.; 2020 Jul.64576 - Xenleta (lefamulin) package insert. Dublin, Ireland: Nabriva Therapeutics US, Inc.; 2019 Aug.64590 - Nourianz (istradefylline) tablets package insert. Bedminster, NJ: Kyowa Kirin, Inc.; 2019 Aug.64697 - Trikafta (elexacaftor; tezacaftor; ivacaftor and ivacaftor tablets) package insert. Boston, MA; Vertex Pharmaceuticals Incorporated: 2019 Oct.64721 - Ibrance (palbociclib) tablets package insert. New York, NY: Pfizer Inc; 2019 Nov.64748 - Brukinsa (zanubrutinib) capsules package insert. San Mateo, CA: BeiGene USA, Inc.; 2019 Nov.64778 - Oxbryta (voxelotor) tablets package insert. South San Francisco, CA: Global Blood Therapeutics, Inc.; 2019 Nov.64845 - Padcev (enfortumab vedotin-ejfv) injection package insert. Northbrook, Illinois: Astellas Pharma US, Inc; 2019 Dec.64870 - Dayvigo (lemborexant) tablets package insert. Woodcliff Lake, NJ: Eisai Inc.; 2019 Dec.64874 - Ubrelvy (ubrogepant) tablets package insert. Madison, NJ: Allergan USA, Inc.; 2019 Dec.64885 - Caplyta (lumateperone) capsules package insert. Hamilton, Bermuda; Intra-Cellular Therapies, Inc.; 2019 Dec.64922 - Ayvakit (avapritinib) tablets package insert. Cambridge, MA:Blueprint Medicines Corporation;2020 Jan.64952 - Tazverik (tazemetostat) tablet package insert. Cambridge, MA: Epizyme, Inc.; 2020 June.65052 - Nurtec ODT (rimegepant) orally disintegrating tablet package insert. New Haven, CT: Biohaven Pharmaceuticals, Inc.; 2020 Mar.65098 - Isturisa (osilodrostat) tablet package insert. Lebanon, NJ: Recordati Rare Disease, Inc.; 2020 Mar.65157 - CredibleMeds. COVID-19 experimental therapies and TdP risk. Available on the World Wide Web at http://https://crediblemeds.org/blog/covid-19-experimental-therapies-and-tdp-risk. Accessed March 23, 2020.65169 - Ozanimod (Zeposia) capsules package insert. Summit, NJ: Celgene Corporation; 2020 Sep.65170 - Giudicessi JR, Noseworthy PA, Friedman PA, Ackerman MJ. Urgent guidance for navigating and circumventing the QTc prolonging and torsadogenic potential of possible pharmacotherapies for COVID-19 [published online ahead of print, March 25, 2020]. Mayo Clin Proc 2020;95.65210 - University of Liverpool. COVID-19 Drug Interactions. Retrived April 6, 2020. Available on the World Wide Web at https://www.covid19-druginteractions.org/.65211 - American Society of Hematology. COVID-19 and VTE/Anticoagulation: Frequently Asked Questions. Retrieved April 6, 2020. Available on the World Wide Web at https://www.hematology.org/covid-19/covid-19-and-vte-anticoagulation.65222 - Karol MD, Maze M. Pharmacokinetics and interaction pharmacodynamics of dexmedetomidine in humans. Bailliere’s Clinical Anaesthesiol 2000;14:261-269.65225 - Oda Y, Hamaoka N, Hiroi T, et al. Involvement of human liver cytochrome P4502B6 in the metabolism of propofol. Br J Clin Pharmacol 2001;51:281-285.65243 - Fett DL, Vukov LF. An unusual case of severe griseofulvin-alcohol interaction. Ann Emerg Med 1994;24:95-97.65246 - Koselugo (selumetinib) capsules package insert. Wilmington, DE: AstraZeneca Pharmaceuticals, LP; 2020 Apr.65250 - Wang ZY, Chen M, Zhu LL, et al. Pharmacokinetic drug interactions with clopidogrel: updated review and risk management in combination therapy. Ther Clin Risk Manag 2015;11:449-467.65295 - Tukysa (tucatinib) tablets package insert. Bothell, WA: Seattle Genetics, Inc.; 2020 April.65307 - Pemazyre (pemigatinib) tablets package insert. Wilmington, DE: Incyte Corporation: 2020 April.65328 - Trodelvy (sacituzumab govitecan-hziy) for injection package insert. Morris Plains, NJ: Immunomedics, Inc.; 2020 April.65377 - Tabrecta (capmatinib) tablets package insert. Novartis Pharmaceuticals Corporation;East Hanover, NJ:2020 May.65387 - Retevmo (selpercatinib) capsules package insert. Indianapolis, IN: Eli Lilly and Company; 2020 May.65431 - Qinlock (ripretinib) tablets package insert. Waltham, MA: Deciphera Pharmaceuticals, LLC; 2020 May.65478 - Elens L, Langman LJ, Hesselink DA, et al. Pharmacologic treatment of transplant recipients infected with SARS-CoV-2: considerations regarding therapeutic monitoring and drug-drug interactions. Ther Drug Monit 2020;42:360-368.65479 - Frassetto L, Baluom M, Jacobsen W, et al. Cyclosporine pharmacokinetics and dosing modifications in human immunodeficiency virus-infected liver and kidney transplant recipients. Transplantation 2005;80:13-17.65480 - Jain AB, Venkataramanan R, Eghtesad B, et al. Effect of coadministered lopinavir and ritonavir (Kaletra) on tacrolimus blood concentration in liver transplantation patients. Liver Transpl 2003;9:954-960.65481 - Frassetto LA, Browne M, Cheng A, et al. Immunosuppressant pharmacokinetics and dosing modifications in HIV-1 infected liver and kidney transplant recipients. Am J Transplant 2007;7:2816-2820.65482 - Vogel M, Voigt E, Michaelis HC, et al. Management of drug-to-drug interactions between cyclosporine A and the protease inhibitor lopinavir/ritonavir in liver-transplanted HIV-infected patients. Liver Transpl 2004;10:939-944.65483 - Marfo K, Greenstein S. Antiretroviral and immunosuppressive drug-drug interactions in human immunodeficiency virus-infected liver and kidney transplant recipients. Transplant Proc 2009;41:3796-3799.65484 - Artesunate for injection package insert. Wilmington, DE: Amivas LLC; 2020 May.65485 - Vesicare LS (solifenacin) oral suspension package insert. Norman, OK: Astellas Pharma Technologies, Inc.; 2020 May.65593 - Zepzelca (lurbinectedin) injection package insert. Palo Alto, CA: Jazz Pharmaceuticals, Inc.; 2020 June.65666 - Rukobia (fostemsavir) package insert. Research Triangle Park, NC: ViiV Healthcare; 2020 Jul.65780 - Cyclophosphamide for injection package insert. Orlando, FL: Ingenus Pharmaceuticals, LLC; 2020 July.65781 - Cyclophosphamide capsules package insert. Eatontown, NJ: West-Ward Pharmaceuticals Corp; 2019 Sept.65782 - Cyclophosphamide powder for solution package insert. Bridgewater, NJ: Amneal Pharmaceuticals LLC; 2019 Nov.65884 - Gavreto (pralsetinib) capsules package insert. Cambridge, MA: Blueprint Medicines Corporation; 2020 Sept.

Monitoring Parameters

  • blood glucose
  • CBC with differential
  • CD4+ T cell count
  • hepatitis B serology
  • LFTs
  • plasma hepatitis C RNA
  • plasma HIV RNA
  • pregnancy testing
  • serum bilirubin (total and direct)
  • serum cholesterol
  • serum lipid profile
  • urinalysis

US Drug Names

  • Kaletra

Global Drug names

Argentina

  • Kaletra - (Abbott)

Australia

  • Kaletra - (AbbVie)

Austria

  • Kaletra - (AbbVie)

Belgium

  • Kaletra - (AbbVie)

Brazil

  • Kaletra - (AbbVie)

Canada

  • Kaletra - (AbbVie)

Chile

  • Kaletra - (Abbott)

China

  • Aluvia - (Abbott)

Czech Republic

  • Kaletra - (AbbVie)

Denmark

  • Kaletra - (AbbVie)

Finland

  • Kaletra - (AbbVie)

France

  • Kaletra - (AbbVie)

Germany

  • Kaletra - (AbbVie)

Greece

  • Kaletra - (AbbVie)

Hong Kong

  • Kaletra - (AbbVie)

Hungary

  • Kaletra - (AbbVie)

India

  • Emletra - (Emcure)
  • Lopimune - (Cipla)
  • Ritomax-L - (Alkem)

Indonesia

  • Aluvia - (Abbott)

Ireland

  • Kaletra - (AbbVie)

Israel

  • Kaletra - (AbbVie)

Italy

  • Kaletra - (Abbott)

Japan

  • Kaletra - (AbbVie)

Malaysia

  • Kaletra - (AbbVie)

Mexico

  • Kaletra - (AbbVie)

Netherlands

  • Kaletra - (AbbVie)

New Zealand

  • Kaletra - (AbbVie)

Norway

  • Kaletra - (AbbVie)

Philippines

  • Aluvia - (Abbott)

Poland

  • Kaletra - (AbbVie)

Portugal

  • Kaletra - (AbbVie)

Russian Federation

  • Kaletra - (AbbVie)

Singapore

  • Kaletra - (AbbVie)

South Africa

  • Aluvia - (Abbott)
  • Kaletra - (Abbott)

Spain

  • Kaletra - (AbbVie)

Sweden

  • Kaletra - (AbbVie)

Switzerland

  • Kaletra - (AbbVie)

Thailand

  • Aluvia - (Zuellig)
  • Kaletra - (Abbott)

Turkey

  • Kaletra - (AbbVie)

Ukraine

  • Aluvia - (AbbVie)
  • Kaletra - (AbbVie)

United Kingdom

  • Kaletra - (Abbott)

Venezuela

  • Kaletra - (Abbott)
  • Kalmeltrex - (Cipla)
  • Rilopravir - (Biogalenic)