From the FDA Drug Label
Coadministration with rifabutin or rifapentine is not recommended. Co-administration of Rifabutin with Biktarvy (bictegravir/ emtricitabin/ tenofovir alafenamide) is not recommended due to an expected decrease in tenofovir alafenamide in addition to the reported reduction in bictegravir
Biktarvy and Rifabutin Interaction:
- The coadministration of Biktarvy and rifabutin is not recommended.
- This is due to the expected decrease in tenofovir alafenamide and the reported reduction in bictegravir.
- Refer to the prescribing information for additional information 1 2.
From the Research
Biktarvy can be used with rifabutin, but requires dosage adjustment, with an additional 50mg tablet of bictegravir taken approximately 12 hours after the Biktarvy dose, as supported by the most recent evidence 3. When co-administered with rifabutin, this adjustment is necessary because rifabutin induces the enzyme CYP3A4, which increases the metabolism of bictegravir, potentially reducing its effectiveness.
- The efficacy and safety of Biktarvy have been established in several studies, including a scoping review that found its efficacy in clinical practice to be comparable to phase III trials 4.
- However, the use of Biktarvy with rifabutin requires careful consideration of the potential drug-drug interactions, as rifabutin can induce the metabolism of bictegravir, leading to reduced bictegravir levels 3.
- Patients should be monitored for side effects of both medications, and adherence to this split dosing schedule is important for maintaining HIV viral suppression.
- If rifabutin therapy is discontinued, the additional bictegravir dose should be stopped as well, returning to the standard once-daily Biktarvy dosing.
- The clinical effectiveness of Biktarvy has been proven non-inferior to other fixed-dose once-daily combinations, and it shows limited drug-drug interactions and a high barrier to drug resistance 3.