Rifabutin + Amprenavir Interaction

Description

Table 2 Rifabutin Interaction Studies Co-administered drug Dosing regimen of co-administered drug Dosing regimen of rifabutin Study population (n) Effect on rifabutin Effect on co-administered drug Recommendation ANTIRETROVIRALS Amprenavir 1200 mg twice a day for 10 days 300 mg once a day for 10 days Healthy male subjects (6) ↑ AUC by 193%, ↑ C max by 119% Reduce rifabutin dose by at least 50%. Fosamprenavir/ ritonavir 700 mg twice a day plus ritonavir 100 mg twice a day for 2 weeks 150 mg every other day for 2 weeks Healthy subjects (15) ↔ AUC a ↓ C max by 15% ↑ AUC by 35% b , ↑ C max by 36%, ↑ C min by 36%, Reduce rifabutin dose by at least 75% (to a maximum 150 mg every other day or three times per week) when given with fosamprenavir/ritonavir combination. Time Curve; C max -Maximum serum concentration; C min - Minimum serum concentration a compared to rifabutin 300 mg once a day alone b compared to historical control (fosamprenavir/ritonavir 700/100 mg twice a day) c also taking zidovudine 500 mg once a day d compared to rifabutin 150 mg once a day alone e compared to rifabutin 300 mg once a day alone f data from a case report g compared to voriconazole 200 mg twice a day alone Other drugs The structurally similar drug, rifampin, is known to reduce the plasma concentrations of a number of other drugs (see prescribing information for rifampin).