Evaluation of Sex Differences of Fosamprenavir (With and Without Ritonavir) in HIV-Infected Men and Women

Abstract

Purpose: Recent studies focusing on HIV-1—infected women have suggested the existence of sex-related differences in natural history, antiretroviral pharmacokinetics, efficacy, and tolerability. This article analyzes three pivotal trials of the protease inhibitor (PI) fosamprenavir (FPV) with a view to providing a better understanding of potential sex differences in efficacy and safety. Method: A post hoc, descriptive analysis was performed on data from 700 subjects (26% women) in three trials of FPV to evaluate sex differences with regard to efficacy, rates of discontinuation, and treatment-related adverse events. Results: No major sex differences were found. Men and women had similarly good antiviral responses, with greater than 60% of treatment-naïve subjects achieving virologic suppression (<400 copies/mL) at 48 weeks. PI-experienced women in CONTEXT receiving once-daily FPV/r experienced the highest rates of discontinuations due to virologic failure (29% in women vs. 8% in men). Women generally had slightly lower rates of liver enzyme elevations and fewer abnormalities of total cholesterol and triglycerides. Conclusion: The absence of major sex differences provides reassurance, but the small number of women in these trials limited the ability to draw conclusions. Future trials should be specifically powered to detect sex differences in safety and efficacy. Key words: antiretroviral efficacy, antiretroviral safety, fosamprenavir, sex differences