Single dose bioequivalence study of two brands of olanzapine 10 mg tablets in Iranian healthy volunteers.

This single dose, randomized, open label, 2-period and crossover study in healthy Iranian adult volunteers was conducted to compare the bioavailability of 2 branded formulations of olanzapine 10 mg tablets. 24 volunteers received one tablet of each olanzapine 10 mg formulation. Drugs were administered after a 12 h overnight fast in each of 2 treatment days which separated by a 2-week washout period. Serial blood samples were collected over a period of 72 h. Plasma was analyzed using a validated high performance liquid chromatography method with ultraviolet detection in the range of 2-24 ng/mL with a lower limit of quantitation of 1.25 ng/mL. A non-compartmental method was employed to determine the pharmacokinetic properties (Cmax, Tmax, AUC0-t, AUC0-∞ and T1/2) to test to bioequivalence. Cmax, AUC0-t and AUC0-∞ were used to test the bioequivalence after log-transformation of plasma data. The mean (SD) Cmax, AUC0-t and AUC0-∞ for the test formulation were 15.82 (3.15) ng/mL, 447.19 (100.64) ng.h/L and 570.75 (130.55) ng.h/L respectively. Corresponding values for the test formulation were 15.72 (4.25) ng/mL, 440.37 (98.75) ng.h/mL and 558.66 (129.57) ng.h/mL. For test formulation vs. the reference formulation, the 90% CIs of the least squares mean test/reference ratios of Cmax, AUC0-t and AUC0-∞ were 97.6-110.0%, 96.4-109.4% and 97.3-109.2%. In these volunteers, based on the FDA regulatory definition, results from the pharmacokinetic analysis suggested that the test and reference formulations of olanzapine 10 mg tablets were bioequivalent.