Tenofovir alafenamide/Selected P-gp Inducers; Phenobarbital Interactions

This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Moderate. These medicines may cause some risk when taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

Some medicines may lower the amount of tenofovir alafenamide in your blood.

What might happen:

The amount of tenofovir alafenamide in your blood may decrease and it may not work as well.

What you should do about this interaction:

Make sure your healthcare professionals (e.g. doctor and pharmacist) know that you are taking tenofovir alafenamide together with apalutamide, carbamazepine, fosphenytoin, lorlatinib, phenobarbital, phenytoin, primidone, rifabutin, rifampin, rifapentine, or St. John's wort, or if you have taken these medicines in the previous week, or if you stopped taking any of these medicines recently. Your doctor may want to change you to a different medication or adjust the dose of your tenofovir alafenamide.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.

  • 1.Descovy (emtricitabine and tenofovir alafenamide) US prescribing information. Gilead Sciences, Inc. April, 2016.
  • 2.Odefsey (emtricitabine, rilpivirine, and tenofovir alafenamide) US prescribing information. Gilead Sciences, Inc. August 21, 2017.
  • 3.Vemlidy (tenofovir alafenamide) US prescribing information. Gilead Sciences, Inc. August, 2020.
  • 4.Cerrone Maddalena, Alfarisi Omamah, Neary Megan, Marzinke Mark A, Parsons Teresa L, Owen Andrew, Maartens Gary, Pozniak Anton, Flexner Charles, Boffito Marta. Rifampicin effect on intracellular and plasma pharmacokinetics of tenofovir alafenamide. 2019 Jun;74(6):1670-1678.
  • 5.This information is based on or an extract from the UW Metabolism and Transport Drug Interaction Database (DIDB) Platform, Copyright University of Washington 1999-2019..

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CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.