Atazanavir with Phenobarbital Interaction Details
Brand Names Associated with Atazanavir
- Atazanavir
- ATZ
- Reyataz®
Brand Names Associated with Phenobarbital
- Phenobarbital
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Feb 29, 2024
Interaction Effect
An increased risk of QT interval prolongation, decreased atazanavir exposure and reduced efficacy of atazanavir
Interaction Summary
Coadministration of atazanavir and PHENobarbital is contraindicated, as this may result in decreased plasma concentrations of atazanavir, a loss of atazanavir therapeutic effect, and development of resistance[1]. Also, concomitant use of PHENobarbital with other products that prolong the QTc interval may result in a greater increase in the QTc interval and adverse reactions associated with QTc interval prolongation. If concomitant use of atazanavir and PHENobarbital cannot be avoided, monitor patients for increased risk of QTc interval prolongation, closely monitor neonates and consider increasing the dosage of the atazanavir accordingly [2].
Severity
Contraindicated
Onset
Unspecified
Evidence
Theoretical
How To Manage Interaction
Coadministration of atazanavir and PHENobarbital is contraindicated, as this may result in decreased plasma concentrations of atazanavir, a loss of atazanavir therapeutic effect, and development of resistance[1]. Also, concomitant use of PHENobarbital with other products that prolong the QTc interval may result in a greater increase in the QTc interval and adverse reactions associated with QTc interval prolongation. If concomitant use of atazanavir and PHENobarbital cannot be avoided, monitor patients for increased risk of QTc interval prolongation, closely monitor neonates and consider increasing the dosage of the atazanavir accordingly [2].
Mechanism Of Interaction
Additive QT interval prolongation; induction of CYP3A-mediated metabolism of atazanavir by PHENobarbital
References
1 ) Product Information: EVOTAZ(R) oral tablets, atazanavir, cobicistat oral tablets. Bristol-Myers Squibb (per manufacturer), Princeton, NJ, 2016.
2 ) Product Information: SEZABY(TM) intravenous injection, phenobarbital sodium intravenous injection. Sun Pharmaceutical Industries Inc (per manufacturer), Cranbury, 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.
Phenobarbital Overview
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Phenobarbital is used to control seizures. Phenobarbital is also used to relieve anxiety. It is also used to prevent withdrawal symptoms in people who are dependent ('addicted'; feel a need to continue taking the medication) on another barbiturate medication and are going to stop taking the medication. Phenobarbital is in a class of medications called barbiturates. It works by slowing activity in the brain.
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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.