Bioequivalence evaluation of two omeprazole enteric-coated formulations in humans

Omeprazole, a proton pump inhibitor, effectively suppresses the gastric acid secretion in the parietal cells of the stomach. Several previously published papers focus on the pharmacokinetics of the drug and its interactions with physiological aspects or with other drugs. The increasing number of omeprazole containing products available in the market, raises questions of therapeutic equivalence and/or generic substitution. The bioequivalence evaluation between two or more formulations provides information about in vivo performance. In a favorable decision regarding bioequivalence, the products are considered to have a similar therapeutic efficacy when used under the same therapeutic conditions. This paper reports the design, results and some important aspects involved in a bioequivalence study between two solid oral formulations from different manufacturers. Some important findings were the high intra-subject variability observed for Cmax and the variability observed between subject profiles, probably caused by the multi-unit type of formulations studied.