Bictegravir

Bictegravir is an antiretroviral medication used to treat HIV-1 infection. It belongs to the class of integrase strand transfer inhibitors (INSTIs), which block the HIV integrase enzyme that inserts viral DNA into the host genome, thereby inhibiting viral replication. In practice, bictegravir is available as part of a fixed-dose single-tablet regimen (Biktarvy) that combines bictegravir with emtricitabine and tenofovir alafenamide.

Indications and administration

Bictegravir is approved for use in adults and certain pediatric patients as part of combination antiretroviral therapy for treatment-naive HIV-1 infection or for virologic suppression in patients on a stable regimen. The standard regimen is a once-daily tablet taken with or without food. The fixed-dose combination aims to provide effective viral suppression with high tolerability.

Pharmacology and pharmacokinetics

Bictegravir is absorbed rapidly and is mainly metabolized by glucuronidation (UGT1A1 and UGT1A3) with a minor contribution from other pathways. It has a long enough half-life to support once-daily dosing. In the Biktarvy tablet, emtricitabine and tenofovir alafenamide contribute additional antiviral activity and help maintain viral suppression.

Safety and resistance

Common adverse effects reported with bictegravir-containing regimens include nausea, diarrhea, fatigue, and headache. Serious adverse events are uncommon but can occur; clinicians monitor for hepatotoxicity and hypersensitivity reactions. Bictegravir has a relatively high barrier to resistance when used with an appropriate nucleoside backbone; adherence is important to prevent resistance development. Resistance mutations in integrase can reduce susceptibility.

Drug interactions and special considerations

Co-administration with strong enzyme inducers (for example, rifampin) lowers bictegravir levels and is generally not recommended. Cation-containing products (such as certain antacids) and other polyvalent cations need to be separated from dosing by several hours. In HIV/hepatitis B coinfection, stopping all HBV-active components may cause a hepatitis flare, so monitoring is advised. Pregnancy data are limited; treatment decisions should be individualized.