Abstract: AIM: To compare the bioavailability of the test and reference formulation of secnidazole (2 g) tablets under fasting conditions. METHODS: This bioequivalence study was carried out in 20 healthy male Chinese volunteers according to a single dose, two-sequence, crossover randomized design.Fifteen blood samples per period were collected over 96 h, and plasma secnidazole concentrations were determined by locally validated high performance liquid chromatography (HPLC) assay and pharmacokinetic parameters were analyzed by the noncompartmental and compartmental methods. RESULTS: Plasma concentration-time profiles were adequately described by a one-compartment open model with first-order absorption.The main pharmacokinetic parameters of secnidazole test and reference tablets were as follows:t_max were (2.30 ±1.06) and (2.28 ±1.10) h, C_max were (49.63 ±6.35) and (46.17 ±4.24) mg/L, t_1/2 were (28.84 ±3.41) and (29.05 ±4.01) h, AUC0-96 were (1832.06 ± 180.15) and (1847.14 ± 204.14) mg·h^-1·L^-1, respectively.The relative bioavailability of test tablets was (99.99 ±11.92) %. CONCLUSION: The results indicate that the two formulations of secnidazole tablets are bioequivalent in the rate and extent of absorption.

Key words: secnidazole tablets, HPLC, pharmacokinetics, bioavailability, bioequivalence