A single-dose, randomized, two-way crossover study comparing two olanzapine tablet products in healthy adult male volunteers under fasting conditions.

BACKGROUND: Olanzapine is a psychotropic agent that belongs to the thienobenzodiazepine class.

OBJECTIVE: The aim of this study was to assess the bioequivalence of 2 commercial 10-mg tablet formulations of olanzapine by statistical analysis of the pharmacokinetic parameters C(max), AUC from 0 to 72 hours after dosing (AUC(0-72)), and AUC(0-infinity) as required by the Egyptian health authority for the marketing of a generic product.

METHODS: This bioequivalence study was carried out in healthy male volunteers using a single-dose, randomized, 2-way crossover design under fasting conditions. Statistical analysis of the pharmacokinetic parameters C(max), AUC(0-72), and AUC(0-infinity) was conducted to determine bioequivalence (after log-transformation of data using analysis of variance and 90% CIs) and to gain marketing approval in Egypt. The formulations were considered to be bioequivalent if the log-transformed ratios of the 3 pharmacokinetic parameters were within the predetermined bioequivalence range (ie, 80%-125%), as established by the US Food and Drug Administration (FDA). Both the test product (Trademark: Integrol((R)) [Global Napi Pharmaceuticals, Cairo, Egypt]) and the reference product (Trademark: Zyprexa((R)) [Eli Lilly and Company, Basingstoke, Hampshire, United Kingdom]) were administered as 10-mg tablets with 240 mL of water after an overnight fast on 2 treatment days, separated by a 2-week washout period. After dosing, serial blood samples were collected for 72 hours. Plasma samples were analyzed using a sensitive, reproducible, and accurate liquid chromatography-tandem mass spectrometry method capable of quantitating olanzapine in the range of 0.167 to 16.7 ng/mL, with a lower limit of quantitation of 0.167 ng/mL. Adverse events were reported by the volunteers as instructed or observed by the resident physician, and were recorded, tabulated, and evaluated.

RESULTS: Twenty-four healthy adult male volunteers participated in this study. Their mean (SD) age was 24.7 (6.2) years (range, 19-41 years), mean weight was 73.4 (6.7) kg (range, 64-89 kg), and mean height was 174.25 (4.6) cm (range, 168-186 cm). Values for C(max), AUC(0-72), AUC(0-infinity), T(max), t(1/2), and the terminal disposition rate constant were found to be in agreement with previously reported values. The differences between the 2 products did not reach statistical significance at P
CONCLUSIONS: In this small study in healthy male volunteers, there were no statistically significant differences in any of the calculated pharmacokinetic parameters between the 10-mg test and reference tablets of olanzapine. The 90% CIs for the ratios of mean C(max), AUC(0-72), and AUC(0-infinity) were within the range of 80% to 125% (using log-transformed data), meeting the FDA regulatory criterion for bioequivalence. Both formulations were well tolerated.