Bioequivalence assay between orally disintegrating and conventional tablet formulations in healthy volunteers

The purpose of this study was to evaluate bioequivalence of two commercial 8 mg tablet formulations of ondansetrona available in the Brazilian market. In this study, a simple, rapid, sensitive and selective liquid chromatography–tandem mass spectrometry method is described for the determination of ondansetron in human plasma samples. The method was validated over a concentration range of 2.5–60 ng/ml and used in a bioequivalence trial between orally disintegrating and conventional tablet ondansetron formulations, to assess its usefulness in this kind of study. Vonau flash® (Biolab Sanus Farmacêutica, Brazil, as test formulations) and Zofran® (GlaxoSmithKline, Brazil, as reference formulation) were evaluated following a single 8 mg dose to 23 healthy volunteers of both genders. The dose was administered after an overnight fast according to a two-way crossover design. Bioequivalence between the products was determinated by calculating 90% confidence interval (90% CI) for the ratio of Cmax, AUC0–t and AUC0–∞ values for the test and reference products, using logarithmically transformed data. The 90% confidence interval for the ratio of Cmax (87.5–103.8%), AUC0–t (89.3–107.2%) and AUC0–∞ (89.7–106.0%) values for the test and reference products is within the 80–125% interval, proposed by FDA, EMEA and ANVISA. It was concluded that two ondansetron formulations are bioequivalent in their rate and extent of absorption.