Coadministration with emtricitabine/tenofovir-DF has not been studied. Tipranavir is primarily metabolised by CYP3A4 and based on metabolism and clearance a clinically significant interaction with emtricitabine is unlikely. Coadministration of tenofovir (300 mg once daily) and tipranavir/ritonavir (500/100 mg twice daily) decreased tenofovir Cmax and AUC by 23% and 2%, but increased Cmin by 7%; tipranavir Cmax, AUC and Cmin decreased by 17%, 18% and 21%, respectively (n=22). Coadministration of tenofovir (300 mg once daily) and tipranavir/ritonavir (750/200 mg twice daily) decreased tenofovir Cmax by 38%, but increased AUC and Cmin by 2% and 14%; tipranavir Cmax, AUC and Cmin decreased by 11%, 9% and 12%, respectively (n=20). No dosage adjustment is necessary. However, a higher risk of renal impairment has been reported in patients receiving tenofovir-DF in combination with a ritonavir boosted protease inhibitor. Close monitoring of renal function is required in these patients.