Comparative bioavailability study with two sodium valproate tablet formulations administered under fasting conditions in healthy subjects

Abstract

Aim: To assess the bioequivalence of two sodium valproate formulations in healthy subjects of both sexes.

Materials and methods: The study was conducted using an open, randomized, two-period crossover design with a 2-week washout interval. Plasma samples were obtained over a 96-hour period. Plasma concentrations of valproate were analyzed by liquid chromatography coupled to tandem mass spectrometry (LC/MS) with negative ion electrospray ionization. From the sodium valproate plasma concentration vs. time curves, the following pharmacokinetic parameters were obtained C_max, AUC, t_max, Ke, and T_1/2.

Results: The geometric mean with corresponding 90% confidence interval for test/reference percent ratios were 104.43% (90% CI 100.42 - 108.61%) for C_max, 98.11% (90% CI = 94.66 - 101.70%) for AUC_last, and 96.71% (90% CI = 92.97 - 100.60%) for AUC_0-inf.

Conclusion: Since the 90% CI for C_max and AUC_last ratios were all inside the 80 - 125% interval proposed by the US Food and Drug Administration Agency (FDA), it was concluded that the new sodium valproate formulation (epilenil 500-mg coated tablet) without food elaborated by Biolab Sanus Farmaceutica Ltda is bioequivalent to depakene formulation for both the rate and the extent of absorption.