Relative bioavailability and pharmacokinetic study of omeprazole 20 mg enteric-coated tablet in healthy Bangladeshi volunteers.

OBJECTIVE: Introduction of omeprazole constituted a break through in the management of acid-related gastric disorders. Omeprazole effectively suppresses the gastric acid secretion in the parietal cells of the stomach. It 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 on the Bangladeshi population. The aim of the study is to assess the relative bioavailability and pharmacokinetic properties of two oral formulations of 20 mg omeprazole tablet, namely LOSEC(R) as reference product and Losectil DR as test product using serum data.

MATERIALS AND METHODS: 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 Losectil DR (Test) and LOSEC (Reference) as a single dose of 20 mg tablet under fasting conditions, following a washout period of 1 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 a non-compartmental method.

RESULTS: From serum data, the obtained values for test and reference products were 593.05 +/- 84.85 and 607.92 +/- 67.07 ng/ ml for Cmax; 1756.71 +/- 287.29 and 1786.90 +/- 280.17 ng-h/ml for AUC0-24; 1889.26 +/- 286.46 and 1929.18 +/- 284.33 ng-h/ml for AUC0- yen, respectively. No statistically significant differences were observed between two formulations by analyzing different pharmacokinetic parameters in terms of period, sequence and formulation. From the paired t-test, no significant differences between two formulations were observed (p > 0.05). The 90% CIs of Cmax, AUC0-24 and AUC0- yen were found to be 91.59 - 122.60%, 101.86 - 116.78% and 102.77 - 116.68%, respectively, which are within the FDA accepted limits for bioequivalence (80 - 125%).

CONCLUSION: Finally it can be concluded that both products are bioequivalent in terms of rate and extent of drug absorption and therefore interchangeable.