Bioequivalence study of 10 mg olanzapine tablets in healthy thai volunteers

Abstract

Objective: The purpose of this study was to compare the bioequivalence of 10 mg tablets of olanzapine between a generic drug (Olapin ® -10; Unison Laboratories Co., Ltd., Thailand) and a reference drug (Zyprexa ® ,Eli Lilly, England) in healthy volunteers. Subjects and methods: A single dose, randomized, 2-period, 2-sequence, crossover study was conducted in 24 healthy Thai male and female volunteers. Each volunteer received a 10 mg tablet of the reference or test drug under fasting condition with a washout period of at least 21 days. Blood samples were obtained at pre-dose and at various time points up to 120 hours after dosing. Olanzapine plasma concentrations were quantified by a validated method employing liquid chromatography with tandem mass spectrometry (LC-MS/MS). Results: 24 volunteers completed both treatment periods. The geometric mean ratios (GMR) (test/reference) between the two formulations of olanzapine were 95.76% (90%CI, 88.55-103.55%) for C max' 103.77% (97.49- 110.46%) for AUC 0-120; and 104.39% (98.20-110.98%) for AUC 0-∞(obs) . There was no statistical difference of the Tmax between the two formulations (p > 0.05). One hundred and eight adverse events were reported from both formulations. Most of the adverse events were judged to be mild in intensity and did not require additional medical treatment. Conclusion: No significant difference in the analysed pharmacokinetic parameters was found between the two formulations of 10 mg olanzapine in the healthy Thai volunteers. The 90%CI of GMR of the pharmacokinetic parameters was entirely within the equivalence criteria (80-125%). Therefore, it can be concluded that this two olanzapine tablet formulations were considered bioequivalent. © 2011 Chatsiricharoenkul S, et al.