Bexarotene with Efavirenz Interaction Details
Brand Names Associated with Bexarotene
- Bexarotene
- Targretin® Capsules
Brand Names Associated with Efavirenz
- Atripla® (as a combination product containing Efavirenz, Emtricitabine, Tenofovir)
- Efavirenz
- Sustiva®
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Mar 04, 2024
Interaction Effect
Reduced efavirenz exposure with reduced efficacy; reduced bexarotene exposure with reduced efficacy
Interaction Summary
Concomitant use of bexarotene and efavirenz should be discouraged due to potential for virologic failure and resistance mutations, thereby reducing efavirenz efficacy. A 70-year-old HIV-1 infected male stabilized on an efavirenz-containing regimen experienced plasma viral load-confirmed virological failure 2 months after coadministration of bexarotene 300 mg/day for exacerbation of mycosis fungoides lesions. Two consecutive subtherapeutic (less than 1000 nanograms/mL) efavirenz plasma concentrations warranted efavirenz dose increase to double the dose prior to bexarotene. Simultaneously, bexarotene plasma concentrations had decreased and only partial efficacy of bexarotene on his cheek lesions was observed[1]. Should concomitant use be required, monitor efavirenz plasma concentrations, HIV RNA levels, and/or CD4 cell counts. In addition, dosage adjustments for either drug may be required .
Severity
Major
Onset
Delayed
Evidence
Probable
How To Manage Interaction
Concomitant administration of bexarotene and efavirenz should be discouraged due to potential for reduced efavirenz plasma concentrations, virologic failure, and resistance mutations, thereby reducing efavirenz efficacy[1]. Should concomitant use be required, monitor efavirenz plasma concentrations, HIV RNA levels, and/or CD4 cell counts.
Mechanism Of Interaction
Induction of either CYP3A4 metabolism or P-glycoprotein efflux of efavirenz by bexarotene; increased clearance of bexarotene by efavirenz
Literature Reports
A) A 70-year-old HIV-1 infected male experienced virological failure and partial resolution of mycosis fungoides lesions following concomitant treatment with efavirenz and bexarotene. The patient received HAART for 14 years, was drug compliant, and had undetectable plasma viral load (pVL) for the past 12 years. His medication regimen consisted of efavirenz/lamivudine/abacavir at the standard doses for the 3 years prior to bexarotene initiation. Following an acute exacerbation of past mycosis fungoides lesions on his cheek, bexarotene 300 mg/day was initiated. Two months after bexarotene initiation, 2 consecutive subtherapeutic (less than 1000 nanograms/mL) efavirenz plasma concentrations warranted efavirenz dose increase, and 2 consecutive pVL above 50 copies/mL confirmed virological failure. Simultaneously, bexarotene plasma concentrations had decreased and only partial efficacy of bexarotene on his cheek lesions was observed [1].
References
1 ) Desnoyer A, Kaied FA, Descamps D, et al: Deleterious pharmacokinetic interaction between bexarotene and efavirenz. AIDS 2010; 24(14):2296-2298.PubMed Abstract: http://www.ncbi.nlm.nih.gov/...
Bexarotene Overview
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Bexarotene is used to treat cutaneous T-cell lymphoma (CTCL, a type of skin cancer) in people whose disease could not be treated successfully with at least one other medication. Bexarotene is in a class of medications called retinoids. It works by stopping the growth of cancer cells.
Efavirenz Overview
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Efavirenz is used along with other medications to treat human immunodeficiency virus (HIV) infection. Efavirenz is in a class of medications called non-nucleoside reverse transcriptase inhibitors (NNRTIs). It works by decreasing the amount of HIV in the blood. Although efavirenz does not cure HIV, it may decrease your chance of developing acquired immunodeficiency syndrome (AIDS) and HIV-related illnesses such as serious infections or cancer. Taking these medications along with practicing safer sex and making other life-style changes may decrease the risk of transmitting (spreading) the HIV virus to other people.
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Definitions
Severity Categories
Contraindicated
These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.
Major
This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.
Moderate
This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.
Minor
While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.
Onset
Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.
Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.
Evidence
Level of documentation of the interaction.
Established: The interaction is documented and substantiated in peer-reviewed medical literature.
Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.
How To Manage The Interaction
Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.
It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.
Mechanism Of Interaction
The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.
Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.
Where Does Our Information Come From?
Information for our drug interactions is compiled from several drug compendia, including:
The prescribing information for each drug, as published on DailyMED, is also used.
Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.
The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.