Comparative bioavailability of two tablet formulations of ranitidine hydrochloride in healthy volunteers

This investigation was carried out to evaluate the bioavailability of a new tablet formulation of ranitidine HCl (300 mg), Ranid, relative to the reference product, Zantac, (300 mg) tablets. The bioavailability was carried out on 24 healthy male volunteers who received a single dose (300 mg) of the test (T) and the reference (R) products in the fasting state, in a randomized balanced 2-way crossover design. After dosing, serial blood samples were collected for a period of 16 hours. Plasma harvested from blood was analyzed for ranitidine by a sensitive and validated high-performance liquid chromatographic assay. The maximum plasma concentration (Cmax), area under the plasma concentration time curve up to the last measurable concentration (AUC0-t), and to infinity (AUC0-infinity) and the absorption rate (Cmax/AUC0-infinity) were analyzed statistically under the assumption of a multiplicative model. The time to maximum concentration (Tmax) was analyzed assuming an additive model. The parametric confidence intervals (90%) of the mean values of the pharmacokinetic characteristics (AUC0-t, AUC0-infinity), Cmax and Cmax/AUC0-infinity) for T/R ratio were in each case well within the bioequivalence acceptable range of 80-125%. The test formulation was found bioequivalent to the reference formulation by the Schuirmann's two one-sided t-tests and by Wilcoxon Mann Whitney two one-sided tests procedure. Therefore, the 2 formulations were considered to be bioequivalent.