Biktarvy should not be co-administered simultaneously with iron supplements under fasted conditions. Biktarvy should be administered at least 2 hours before iron supplements, or taken together with food. Simultaneous administration of ferrous fumarate (324 mg single dose) and bictegravir decreased bictegravir AUC and Cmax by 63% and 71% under fasting conditions, but had no significant effect on AUC and decreased Cmax by 25% when given with food.

Coadministration may decrease bictegravir concentrations. Biktarvy and supplements containing iron can be taken together with food. Routine administration of Biktarvy under fasting conditions together with, or 2 hours after, supplements containing iron is not recommended. Simultaneous coadministration of ferrous fumarate (324 mg single dose) and bictegravir (50 mg single dose) under fasting conditions decreased bictegravir Cmax and AUC by 71% and 63%. Simultaneous coadministration of ferrous fumarate (324 mg single dose) and bictegravir (50 mg single dose) with food decreased bictegravir Cmax and AUC by 25% and 16% when compared to bictegravir alone under fasting conditions.

Bictegravir/emtricitabine/tenofovir alafenamide (50/200/25 mg single dose) was administered to adult participants without HIV (n=14) simultaneously, under fasted or fed conditions, with/without ferrous fumarate (324 mg single dose). Simultaneous administration decreased bictegravir AUC by 63% in fasting conditions and by 16% in fed conditions.