Biktarvy should not be co-administered with other antiretroviral medicinal products. Co-administration of bictegravir with medicinal products that potently inhibit both CYP3A and UGT1A1, such as atazanavir, may significantly increase plasma concentrations of bictegravir, therefore co-administration is not recommended. Coadministration of atazanavir/cobicistat (300/150 mg once daily) and bictegravir (75 mg single dose) increased bictegravir AUC by 306% but had no effect on Cmax (due to inhibition of CYP3A, UGT1A1, and P-gp/BCRP). Coadministration of atazanavir alone (400 mg once daily) and bictegravir (75 mg single dose) increased bictegravir AUC by 315% but had no effect on Cmax (due to inhibition of CYP3A and UGT1A1).

As Biktarvy is a complete regimen, coadministration with other antiretroviral medications for the treatment of HIV-1 infection is not recommended.

Coadministration of bictegravir (75 mg) and atazanavir alone or atazanavir/cobicistat was studied in healthy subjects (n=15). Coadministration with atazanavir alone increased bictegravir AUC by 310%, due to inhibition of UGT1A1 and CYP3A4. A similar magnitude of increase occurred with atazanavir/cobicistat.