Coadministration is not recommended. Coadministration with bictegravir/emtricitabine/tenofovir alafenamide has not been studied. Coadministration of rifabutin (300 mg once daily) and bictegravir alone (75 mg once daily) decreased bictegravir Cmax, AUC and Cmin by 20%, 38% and 56%, respectively. Furthermore, rifabutin is an inducer of P-gp and is expected to decrease the absorption of tenofovir alafenamide absorption and thereby plasma concentrations.