Single-Dose Pharmacokinetic Properties, Bioavailability, and Tolerability of Two Lamivudine 100-mg Tablet Formulations: A Randomized Crossover Study in Healthy Chinese Male Subjects

Background: Lamivudine is used in the treatment of HIV and chronic hepatitis B (HBV) infections. Since 1999, at least 2 million Chinese HBV patients have been treated with lamivudine, but there are limited studies on the pharmacokinetics and safety of the drug in Chinese populations. Objective: This study was designed to assess the bioequivalence of a newly developed lamivudine tablet (test drug) and a branded lamivudine tablet (reference drug) in healthy Chinese male volunteers. Methods: A single-center, single-dose, randomized, open-label, 2-period crossover study was conducted in 28 healthy Chinese male volunteers. Blood samples were collected up to 24 hours after the administration of oral lamivudine 100 mg in each period. Plasma lamivudine concentrations were analyzed by a validated LC-MS/MS method. Pharmacokinetic and bioavailability parameters were calculated. Adverse events (AEs) were recorded. Results: There were no significant differences in mean (SD) pharmacokinetic parameters between the test and reference drugs, including C-max (1239 [328.9] ng/mL vs 1176 [341.5] ng/mL), AUC(0-t) (4096 [599.1] ng . h/mL vs 4064 [678.2] ng . h/mL), and AUC(0-infinity) (4200 [607.7] ng . h/mL vs 4162 [672.2] ng . h/mL). The geometric mean test/reference ratios (90% CI) calculated for the log-transformed parameters were C-max, 1.06 (96.21-116.90); AUC(0-t), 1.01 (96.53-105.39); and AUC(0-infinity), 1.01 (96.81-105.16), all of which were within the acceptance limits for bioequivalence. No serious AEs were reported, and all mild AEs were recovered quickly without treatment. Conclusion: These findings suggest that the test formulation of lamivudine 100 mg meets the FDA regulatory standards for bioequivalence with the reference formulation. Both formulations were well tolerated. (C) 2013 Elsevier HS Journals, Inc. All rights reserved.