Relative bioavailability of two enteric-coated formulations of omeprazole following repeated doses in healthy volunteers

Objective: This study aimed to investigate the relative bioavailability and bioequivalence of two omeprazole enteric-coated formulations following rep eated doses (steady state) in healthy male and female adult volunteers. Design and Study Participants: The study formulation (Ompranyt (R) 20mg cap sules, Bial-Industrial Farmaceutica SA, Spain) was compared with an omepraz ole reference formulation (Mopral (R) 20mg capsules, Laboratorio Astra, Spa in). 24 participants were randomised using a two-way, crossover design to r eceive either one capsule/day of Ompranyt (R) or one capsule/day of Mopral (R) during two sequential periods of five consecutive days each. The partic ipants were administered the drugs in the fasting state. Omeprazole concent rations in plasma samples were quantified by a validated method using a rev ersed-phase high performance liquid chromatography with UV detection (HPLC- UV). The validation method is described. Setting: The study was conducted at the Human Pharmacology Unit, Department of Research & Development, Laboratories Bial (S. Mamede do Coronado, Portu gal). Results: The arithmetic mean +/- SD values of the area under the plasma con centration Versus time curve from time zero to infinity (AUC(0-infinity),) were 1474 +/- 1417 mug/L .h for Ompranyt (R) and 1490 +/- 1276 mug/L .h for Mopral (R). The geometric means ratio (Ompranyt (R) /Mopral (R)) was 0.99, with 90% confidence intervals (CI) of 0.97-1.03. The estimated maximum pla sma concentration (C-max) was 630.1 +/- 516.7 mug/L for Ompranyt (R) and 73 6.7 +/- 443.3 mug/L for Mopral (R), with a geometric means ratio (Ompranyt (R) /Mopral (R)) of 0.96 (90% CI: 0.94-0.99). Bioequivalence of these two f ormulations was accepted based on the two one-sided ANOVA for AUC(0-infinit y) as well as for Cmax. In both cases, the 90% CI lies within the acceptanc e range of 0.80-1.25. Conclusion: Bioequivalence of Ompranyt (R) and Mopral (R) was demonstrated after repeated drug administration in fasting conditions, and both products were similarly well tolerated. Therefore, both formulations are expected t o be equivalent in a clinical setting.