A Single-dose, Randomized, Open-label, Two-period Crossover Bioequivalence Study Comparing a Fixed-Dose Pediatric Combination of Lamivudine and Stavudine Tablet for Oral Suspension with Individual Liquid Formulations in Healthy Adult Male Volunteers

Abstract

Lamivudine (CAS 134678-17-4) is a synthetic nucleoside analogue with activity against HIV-1 and HBV. Stavudine (CAS 3056-17-5) is a synthetic thymidine nucleoside analogue, active against the human immunodeficiency virus (HIV). Lamivudine and stavudine in combination with other antiretroviral (ARV) agents are indicated for the treatment of HIV infection. As there are no suitable pediatric ARVs, adult fixed-dose ARVs are commonly used in children. This practice poses concerns about dose inaccuracy, which may lead to resistance or toxicity. A new fixed-dose combination (FDC) tablet for oral suspension, containing lamivudine 40 mg and stavudine 10 mg has been developed. An open-label, balanced, randomised, two-treatment, two-period, two-sequence, single-dose, crossover bioequivalence study was conducted following administration of a fixed-dose combination of lamivudine and stavudine tablet for oral suspension (test formulation) and innovator products (reference formulations) in healthy, adult, male human subjects under fasting condition. Multiple blood samples were collected up to 36 h post dose. Plasma concentrations of lamivudine and stavudine were assayed using validated high-performance liquid chromatography with mass spectrometry analytical method. Pharmacokinetic parameters were calculated using non-compartmental analysis and bioequivalence was assessed using a mixed effect ANOVA model. The ratio of the least-square means (FDC to individual products) and 90% confidence intervals (CIs) of AUC(0-t), AUC(0-infinity) and C(max) for lamivudine and stavudine were all within 80.00-125.00%, suggesting a similar rate and extent of ARVs exposure in the bloodstream. The FDC and individual products were equally safe and well tolerated. The current FDC of lamivudine and stavudine is expected to provide a similar efficacy/safety profile as co-administration of the individual products, a better adherence to treatment, and considerable cost savings in the treatment of HIV in children.