Lower Dose of Ritonavir Approved for Use with Fosamprenavir

On October 12, 2007, the FDA approved a new dose of ritonavir (100 mg once daily) for boosting fosamprenavir (1400 mg once daily) in treatment-naive HIV-infected patients. Approval was based on data from an industry-sponsored pharmacokinetic study, in which investigators compared the new 100-mg once-daily dose of ritonavir with a previously approved dose (200 mg once daily) in 36 healthy volunteers who also received once-daily fosamprenavir. Plasma levels of fosamprenavir were comparable with the two ritonavir doses after 14 days, but the lower dose of ritonavir was associated with fewer adverse events and smaller mean increases in triglyceride levels (Antimicrob Agents Chemother 2007; 51:560). Two pilot studies of this dosing strategy in t…