Atazanavir with Efavirenz Interaction Details
Brand Names Associated with Atazanavir
- Atazanavir
- ATZ
- Reyataz®
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
Feb 29, 2024
Interaction Effect
Reduced atazanavir exposure and an increased risk of QT interval prolongation
Interaction Summary
Concomitant administration of efavirenz decreases atazanavir exposure. Atazanavir should be coadministered with ritonavir if efavirenz is to be added to the patient's drug regimen. In treatment-naive patients, give atazanavir 400 mg with ritonavir 100 mg once daily as a single dose with food and efavirenz 600 mg on an empty stomach, preferably at bedtime. . Atazanavir should not be coadministered with efavirenz in treatment-experienced patients[1]. Consider alternatives to efavirenz when used concomitantly with another drug that prolongs the QT interval, such as atazanavir, because additive effects on the QT interval may also occur [2]. Coadministration of atazanavir/cobicistat with efavirenz is not recommended because it may result in a loss of therapeutic effect and development of resistance to atazanavir [3].
Severity
Major
Onset
Unspecified
Evidence
Established
How To Manage Interaction
Coadministration of atazanavir and efavirenz resulted in a decreased atazanavir plasma concentrations. If atazanavir and efavirenz are coadministered in treatment-naive patients, atazanavir 400 mg with ritonavir 100 mg once daily as a single dose with food, and efavirenz 600 mg administered on an empty stomach, preferably at bedtime is recommended. Atazanavir should not be coadministered with efavirenz in treatment-experienced patients[1]. Consider alternatives to efavirenz when used concomitantly with another drug that prolongs the QT interval, such as atazanavir, because additive effects on the QT interval may also occur [2]. Coadministration of atazanavir/cobicistat with efavirenz is not recommended because it may result in a loss of therapeutic effect and development of resistance to atazanavir [3].
Mechanism Of Interaction
Induction of CYP3A-mediated atazanavir metabolism by efavirenz; additive QT interval prolongation
Literature Reports
A) Efavirenz reduced the concentrations of atazanavir; however, when ritonavir was added to the regimen and the efavirenz was administered 2 hours after atazanavir/ritonavir, the concentrations of atazanavir increased. Atazanavir 400 mg once daily on days 1 to 20, and efavirenz 600 mg once daily on days 7 to 20 was administered with a light meal to 27 patients. The resulting atazanavir Cmax, AUC, and Cmin decreased by 59% (95% confidence interval (CI), 49% to 63%), 74% (95% CI, 68% to 78%), and 93% (95% CI, 90% to 95%), respectively, when compared to atazanavir 400 mg alone. When atazanavir was changed to 400 mg once daily on days 1 to 6, then 300 mg plus ritonavir 100 mg once daily on days 7 to 20, and efavirenz 600 mg once daily (days 7 to 20) was administered 2 hours after atazanavir and ritonavir, the Cmax, AUC, and Cmin for atazanavir increased by 14% (95% CI, 17% decrease to 58% increase), 39% (95% CI, 2% to 88%), and 48% (95% CI, 24% to 76%), respectively [1].
B) Atazanavir 400 mg/ritonavir 100 mg once daily in the evening administered simultaneously with efavirenz 600 mg once daily resulted in a 17% increase in Cmax (95% confidence interval (CI), 8% to 27%), no change in AUC (95% CI, 9% decrease to 10% increase), and a 42% decrease in Cmin (95% CI 31% to 41% decrease) [1].
References
1 ) Product Information: REYATAZ(R) oral capsules, oral powder, atazanavir oral capsules, oral powder. Bristol-Myers Squibb Company (per FDA), Princeton, NJ, 2020.
2 ) Product Information: SUSTIVA(R) oral capsules, oral tablets, efavirenz oral capsules, oral tablets. Bristol-Myers Squibb Company (per FDA), Princeton, NJ, 2016.
3 ) Product Information: EVOTAZ(R) oral tablets, atazanavir cobicistat oral tablets. Bristol-Myers Squibb Company (per FDA), Princeton, NJ, 2023.
Atazanavir Overview
-
Atazanavir is used along with other medications to treat human immunodeficiency virus (HIV) infection in adults and children who are at least 3 months of age and weigh at least 22 lb (10 kg). Atazanavir is in a class of medications called protease inhibitors. It works by decreasing the amount of HIV in the blood. Although atazanavir 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. Atazanavir must be given with other medications that treat HIV infection to completely treat the infection. Taking these medications along with practicing safer sex and making other lifestyle changes may decrease the risk of transmitting the HIV virus to other people.
Efavirenz Overview
-
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.
Return To Our Drug Interaction Homepage
Feedback, Question Or Comment About This Information?
Ask Dr. Brian Staiger, PharmD, our medical editor, directly! He's always more than happy to assist.
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.