Bictegravir is a second‑generation HIV‑1 integrase strand transfer inhibitor (INSTI) used as part of antiretroviral therapy, almost exclusively in a fixed‑dose combination tablet with emtricitabine and tenofovir alafenamide (Biktarvy).
Bictegravir binds to the HIV‑1 integrase enzyme and blocks the strand transfer step that inserts viral DNA into host cell DNA, preventing formation of a stable provirus and halting viral replication.
It has potent in vitro activity against multiple HIV‑1 subtypes and HIV‑2, and retains activity against many viruses resistant to first‑generation INSTIs.
Clinically, bictegravir is marketed only as part of a single daily tablet containing bictegravir, emtricitabine, and tenofovir alafenamide (B/F/TAF)
B/F/TAF is approved as a complete regimen for treatment of HIV‑1 infection in adults and children above certain weight/age thresholds, for both treatment‑naïve individuals and many virologically suppressed patients switching therapy.
The standard adult dose of the fixed‑dose combination is one tablet taken orally once daily, with or without food, with no separate bictegravir dose adjustment needed in most patients.
Dose adjustments or avoidance may be required in significant renal impairment, driven by the tenofovir alafenamide component) or in certain hepatic conditions.
Common adverse effects include headache, nausea, diarrhea, and fatigue; overall tolerability is generally favorable compared with many older regimens.
Side effects: include increases in serum creatinine (via inhibition of tubular secretion rather than true GFR decline), weight gain typical of INSTI‑based therapy, and rare cases of hepatotoxicity or lactic acidosis when combined with other NRTIs.
Bictegravir is metabolized by CYP3A4 and UGT1A1; strong inducers such as rifampin can markedly reduce bictegravir levels and are contraindicated or not recommended.
Use with dofetilide is contraindicated due to increased dofetilide concentrations and risk of serious arrhythmias; caution is also advised with polyvalent cation antacids and supplements, which should be separated in time from dosing.