Steady State Bioequivalence of Generic and Innovator Formulations of Stavudine, Lamivudine, and Nevirapine in HIV-Infected Ugandan Adults

BACKGROUND: Generic antiretroviral therapy is the mainstay of HIV treatment in resource-limited settings, yet there is little evidence confirming the bioequivalence of generic and brand name formulations. We compared the steady-state pharmacokinetics of lamivudine, stavudine and nevirapine in HIV-infected subjects who were receiving a generic formulation (Triomune®) or the corresponding brand formulations (Epivir®, Zerit®, and Viramune®). METHODOLOGY/PRINCIPAL FINDINGS: An open-label, randomized, crossover study was carried out in 18 HIV-infected Ugandan subjects stabilized on Triomune-40. Subjects received lamivudine (150 mg), stavudine (40 mg), and nevirapine (200 mg) in either the generic or brand formulation twice a day for 30 days, before switching to the other formulation. At the end of each treatment period, blood samples were collected over 12 h for pharmacokinetic analysis. The main outcome measures were the mean AUC(0–12h) and C(max). Bioequivalence was defined as a geometric mean ratio between the generic and brand name within the 90% confidence interval of 0.8–1.25. The geometric mean ratios and the 90% confidence intervals were: stavudine C(max), 1.3 (0.99–1.71) and AUC(0–12h), 1.1 (0.87–1.38); lamivudine C(max), 0.8 (0.63–0.98) and AUC(0–12h), 0.8 (0.65–0.99); and nevirapine C(max), 1.1 (0.95–1.23) and AUC(0–12h), 1.1 (0.95–1.31). The generic formulation was not statistically bioequivalent to the brand formulations during steady state, although exposures were comparable. A mixed random effects model identified about 50% intersubject variability in the pharmacokinetic parameters. CONCLUSIONS/SIGNIFICANT FINDINGS: These findings provide support for the use of Triomune in resource-limited settings, although identification of the sources of intersubject variability in these populations is critical.