A higher risk of renal impairment has been reported in HIV-1 infected patients receiving tenofovir disoproxil fumarate in combination with a ritonavir or cobicistat boosted protease inhibitor. Close monitoring of renal function is required in these patients. In HIV-1 infected patients with renal risk factors, the co-administration of tenofovir disoproxil fumarate with a boosted protease inhibitor should be carefully evaluated. Coadministration of atazanavir/ritonavir (300/100 mg once daily) was studied with tenofovir disoproxil fumarate (300 mg once daily). Atazanavir AUC, Cmax and Cmin decreased by 25%, 28% and 26%, respectively. Tenofovir AUC, Cmax and Cmin increased by 37%, 34% and 29%, respectively. Co-administration of atazanavir/ritonavir and emtricitabine has not been studied. No dose adjustment is recommended. The increased exposure of tenofovir could potentiate tenofovir-associated adverse events, including renal disorders. Renal function should be closely monitored. 

Coadministration with atazanavir alone decreases atazanavir concentrations. Coadministration with atazanavir/ritonavir increases tenofovir concentrations. Coadministration of atazanavir (400 mg once daily) and tenofovir-DF (300 mg once daily) was studied in 33 subjects. Tenofovir Cmax, AUC and Cmin increased by 14%, 24% and 22%, respectively. Atazanavir Cmax, AUC and Cmin decreased by 21%, 25% and 40%, respectively. Coadministration of atazanavir/ritonavir (300/100 mg once daily) and tenofovir-DF (300 mg once daily) was studied in 10 subjects. Tenofovir Cmax, AUC and Cmin increased by 34%, 37% and 29%, respectively. Atazanavir Cmax, AUC and Cmin decreased by 28%, 25% and 23%, respectively. When coadministered with Truvada, atazanavir 300 mg should be given with ritonavir 100 mg. Monitor patients receiving Truvada concomitantly with ritonavir-boosted atazanavir for TDF-associated adverse reactions. Discontinue Truvada in patients who develop TDF-associated adverse reactions.