Bioequivalence and pharmacokinetic study of two different omeprazole capsule formulations in healthy Bangladeshi volunteers.

Omeprazole (CAS 73590-58-6) effectively suppresses the gastric acid secretion in the parietal cells of the stomach and is a widely prescribed proton pump inhibitor in Bangladesh. The increasing number of omeprazole containing products available in the market raises questions of therapeutic equivalence and/or generic substitution which are yet to be conducted with Bangladeshi population. The aim of the study is to assess the bioequivalence and pharmacokinetic properties of two oral formulations of 20 mg omeprazole capsule, the reference product and Omep-20 as test product using serum data. The randomized, two-way crossover study was conducted on 24 healthy male subjects in compliance with the Declaration of Helsinki and ICH guidelines. Subjects were assigned to receive test and reference as a single dose of 20 mg capsule under fasting condition, following a washout period of one week. After oral administration, blood samples were collected at various time intervals and analyzed for omeprazole concentrations using a validated HPLC method. The pharmacokinetic parameters were determined by non-compartmental method. From serum data, the obtained values for test and reference products were 648.07 +/- 216.27 and 632.69 +/- 257.01 ng/ml for Cmax; 2012.24 +/- 634.48 and 1907.86 +/- 761.91 ng x h/ml for AUC0-24; 2105.21 +/- 623.79 and 1979.18 +/- 748.12 ng x h/ml for AUC0-infinity respectively. No statistically significant differences were observed between two formulations by analyzing different pharmacokinetic parameters in terms of period, sequence or formulation. From the paired t-test, no significant differences between two formulation were observed (p > 0.05). The 90% confidence intervals of Cmax, AUC0-24 and AUC0-infinity were found to be 91.59% to 122.60%, 101.86% to 116.78% and 102.77% to 116.68% respectively which are within the FDA accepted limits for bioequivalence (80%-125 %). Finally it can be concluded that both products are bioequivalent in terms of rate and extent of drug absorption and therefore interchangeable.