Atazanavir with Avanafil Interaction Details
Brand Names Associated with Atazanavir
- Atazanavir
- ATZ
- Reyataz®
Brand Names Associated with Avanafil
- Avanafil
- Stendra®
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Feb 29, 2024
Interaction Effect
Decreased avanafil clearance and increased avanafil plasma concentrations
Interaction Summary
Concomitant administration of atazanavir (a strong CYP3A4 inhibitor)[1] and avanafil (a CYP3A4 substrate) may result in increased avanafil exposure and toxicity. Compared with the pharmacokinetics of avanafil alone, the administration of a single dose of avanafil 50 mg with ketoconazole 400 mg/day (also a strong CYP3A4 inhibitor) resulted in a 13-fold increase in AUC, 3-fold increase in Cmax, and a prolonged half-life of 9 hours for avanafil. Although not specifically studied with atazanavir, other strong CYP3A4 inhibitors would be expected to have similar effects. Atazanavir and avanafil should not be used concomitantly [2].
Severity
Major
Onset
Unspecified
Evidence
Theoretical
How To Manage Interaction
Atazanavir (a CYP3A4 inhibitor)[1] should not be used concomitantly with avanafil (a CYP3A4 substrate), as this may result in increased avanafil exposure and toxicity [2].
Mechanism Of Interaction
Inhibition of CYP3A4-mediated metabolism of avanafil by atazanavir
References
1 ) Product Information: REYATAZ(R) oral capsules, atazanavir sulfate oral capsules. Bristol-Myers Squibb (per Manufacturer), Princeton, NJ, 2012.
2 ) Product Information: STENDRA(R) oral tablets, avanafil oral tablets. Metuchen Pharmaceuticals LLC (per FDA), Freehold, NJ, 2022.
Atazanavir Overview
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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.
Avanafil Overview
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Avanafil is used to treat erectile dysfunction (ED: impotence; inability to get or keep an erection in men). Avanafil is in a class of medications called phosphodiesterase (PDE) inhibitors. It works by increasing blood flow to the penis during sexual stimulation. This increased blood flow can cause an erection. Avanafil does not cure erectile dysfunction or increase sexual desire. Avanafil does not prevent pregnancy or the spread of sexually transmitted diseases such as human immunodeficiency virus (HIV).
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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.