The present study suggests that the test 500-mg amoxicillin capsule was bioequivalent to the reference 500-mg capsule according to the FDA regulatory definition, in this population of healthy adult male 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.

A Simple RP-HPLC method with UV detection has been validated to determine omeprazole concentrations in human serum and urine samples. The mobile phase consisted of a mixture of potassium dihydrogen phosphate buffer (pH 7.2 ± 0.05; 0.2 M) and acetonitrile (70:30, v/v), pumped at a flow rate of 1.0 ml/min through the C-8 column at room temperature. Peaks were monitored by UV absorbance at 302 nm at a sensitivity of 0.0001. The developed method was selective and linear for omeprazole concentrations ranging between 5 to 1000ng/ml for serum samples and 1 to 100μg/ml for urine samples. The recovery of omeprazole ranged from 95.68 to 99% and 95.54 to 99.8% for the serum and urine samples respectively. The limit of quantitation (LOQ) of omeprazole was 5 ng/ml. The intraday accuracy ranged from 93.54 to 104.38% and 100.55 to 103.48% for the serum and urine respectively. The interday accuracy varied from 97.61 to 113.95% and 97.42 to 109.97% for the serum and urine respectively. For the LOQ, good values of precision (6.03 and 10.13% for intraday and interday, respectively) were also obtained. Acceptable results were obtained during stability study. This method proved to be simple, accurate and precise for pharmacokinetic and bioequivalence studies of omeprazole. Key words: Omeprazole; RP-HPLC; Method validation. DOI: 10.3329/dujps.v8i2.6026 Dhaka Univ. J. Pharm. Sci. 8(2): 123-130, 2009 (December)