Bioavailability of two single-dose oral formulations of omeprazole 20 mg: an open-label, randomized sequence, two-period crossover comparison in healthy Mexican adult volunteers.

BACKGROUND: Omeprazole is a proton-pump inhibitor that acts to reduce acid secretion in the stomach and is used for treating various acid-related gastrointestinal disorders. There are several generic formulations of omeprazole available in Mexico; however, a literature search failed to identify published data concerning the bioavailability of these formulations in the Mexican population. OBJECTIVE: The aim of this study was to compare the bioavailability of 2 oral formulations of omeprazole 20-mg capsules, marketed for use in Mexico, in healthy volunteers: Inhibitron (test formulation) and LosecA 20 mg (reference formulation). METHODS: This study used a single-dose, open-label, randomized sequence, 2 x 2 crossover (2 administration periods x 2 treatments) design to compare the 2 formulations. Eligible subjects were healthy adult Mexican volunteers of both sexes. Subjects were randomly assigned in a 1:1 ratio to receive a single 20-mg dose of the test formulation followed by the reference formulation, or vice versa, with a 7-day washout period between administration periods. After a 12-hour (overnight) fast, subjects received a single, 20-mg dose of the corresponding formulation. Plasma samples were obtained over a 12-hour period after administration. Plasma omeprazole concentrations were analyzed by a nonstereospecific high-performance liquid chromatography method. For analysis of pharmacokinetic properties, including C(max), AUC from time 0 (baseline) to time t (AUC(0-t)), and AUC from baseline to infinity (AUC(0-infinity)), blood samples were drawn at baseline and 0.17, 0.33, 0.50, 0.75, 1, 1.25, 1.50, 1.75, 2, 2.50, 3, 4, 6, 8, and 12 hours after administration. The formulations were considered bioequivalent if the natural log (ln)-transformed ratios of C(max) and AUC were within the predetermined equivalence range of 80% to 125%, and if P