Emtricitabine/Tenofovir-DF (FTC/TDF, PrEP)
Darunavir + ritonavir (DRV/r)
Quality of Evidence: Very Low
Coadministration with emtricitabine/tenofovir-DF has not been studied. Based on metabolism and clearance a clinically significant interaction is unlikely with emtricitabine as it is primarily renally excreted and darunavir/ritonavir is unlikely to inhibit OCTs at clinically relevant concentrations. Coadministration of tenofovir-DF (300 mg once daily) and darunavir/ritonavir (300/100 mg twice daily, a dose lower than that licensed) increased darunavir Cmax (16%), AUC (21%) and Cmin (24%). Tenofovir Cmax, AUC and Cmin increased by 24%, 22% and 37%, respectively. No adjustments to the licensed doses are required. A higher risk of renal impairment has been reported in patients receiving tenofovir-DF and a ritonavir or cobicistat boosted protease inhibitor. Close monitoring of renal function and for tenofovir-associated adverse reactions is required in these patients.