A randomized study of pharmacokinetics, efficacy, and safety of 2 raltegravir plus atazanavir strategies in ART-treated adults.

Background: New antiretroviral drug classes provide opportunities to explore novel regimens.

Methods: HIV+ adults (<50 copies/mL) receiving atazanavir (ATV) were randomized to raltegravir (RAL) 400 mg + ATV 300 mg twice daily (q12h) for 4 weeks followed by RAL 800 mg + ATV/ritonavir 300/100 mg once daily (q24h) for 4 weeks or vice versa. Validated assays quantitated RAL and ATV plasma concentrations. Primary endpoint was geometric mean ratio (GMR) of ATV minimum concentration (Cmin) for q24h/q12h. Equivalence was 90% confidence interval (CI) of GMR lying between 0.80 and 1.25. Participants could consent to a total 48-week follow-up.

Results: Twenty-five men, mean age 45 (range, 35-57) years, were evaluated. ATV and RAL demonstrated considerable pharmacokinetic variability. There was no period or sequence effect for pharmacokinetic parameters (P > 0.1 all measures). Ninety percent CIs of ATV GMR C(min) [1.30 (90% CI: 1.08 to 1.58)] and RAL GMR C(min) [0.48 (90% CI: 0.31 to 0.75)] demonstrated nonequivalence. Seventy-six percent consented to follow-up. There were no serious adverse events and no discontinuations due to adverse events over 48 weeks; HIV RNA remained undetectable.

Conclusions: In virologically suppressed adults, regimens comprising ATV plus RAL were efficacious and safe. ATV q12h troughs were lower than ritonavir-boosted atazanavir q24h; RAL q24h troughs were lower than q12h.