Coadministration of sofosbuvir/velpatasvir (with voxilaprevir) and bictegravir/tenofovir alafenamide (50/25 mg once daily) increased sofosbuvir Cmax and AUC by 14% and 9%; Cmax, AUC and Cmin of GS-331007 (the predominant circulating nucleoside metabolite of sofosbuvir) increased by 3%, 3% and 1%. Velpatasvir Cmax, AUC and Cmin decreased by 4%, 4% and 6%.

Coadministration of bictegravir/emtricitabine/tenofovir alafenamide (50/200/25 mg once daily) and sofosbuvir/velpatasvir/voxilaprevir (400/100/100 once daily, plus 100 mg voxilaprevir to approximate systemic voxilaprevir exposure in HCV-infected subjects) was studied in healthy volunteers (n=30). Bictegravir and emtricitabine AUCs were unaltered by coadministration, but AUC of tenofovir alafenamide increased by ~58% and AUC of tenofovir increased by ~67%. There was no effect of coadministration on AUCs of sofosbuvir, GS-331007 (the major circulating metabolite of sofosbuvir), velpatasvir or voxilaprevir.