Bioequivalence study of two enteric coated capsule formulations of omeprazole in healthy volunteers

Abstract

Medical profession has realized the problem of wide variations in the therapeutic effectiveness of various brands of oral formulations containing the same active ingredient in equal amounts. The study was conducted as an open label, balanced, randomized, two-treatment, two-period, two-sequence single-dose crossover study to determine the bioequivalence of Lomac 20-mg and Protoloc 20-mg enteric coated capsules under fasting conditions. A group of 12 healthy, adult, male human subjects participated in the study. The bioavailability was compared using pharmacokinetic parameters Cmax, Tmax, AUC0-t, and AUC0-∞. Moreover, the 90% confidence interval (CI) for the ratio of logarithmic transformed Cmax, AUC0-t and AUC0-∞ was also used to determine bioequivalence. A washout period of seven days was kept between each study period. Serial blood samples were collected at 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 8, 10, 12 h post dose during each study. The samples were analyzed using high performance liquid chromatography (HPLC) by liquid-liquid extraction method using lansoprazole as a reference standard. The 90% CI for the log transformed data for Cmax, AUC0-t, and AUC0-∞ for the test product were 72.13-152.7, 58.49-144.28 and 61.77-136, respectively. The T/R (test/reference) ratio of the product was quite close to the prescribed limits of bioequivalence i.e., 94% (95-105%). There was no period, sequence, formulation effect as indicated by the p values. The test product of omeprazole i.e., Lomac was not bioequivalent to the reference product i.e. Protoloc but bioavailability of the test product was quite satisfactory i.e. 94%. Keywords: bioequivalence, omeprazole, pharmacokinetics, bioavailability, healthy volunteers Ethiopian Pharmaceutical Journal Vol. 23 2005: 45-52