Comparative, Single-Dose, 2-Way Cross-Over Bioavailability Study of Two Olanzapine 10 Mg Tablet Formulations in Healthy Volunteers Under Fasting Conditions

Objectives: Olanzapine is an atypical antipsychotic that is approved across Europe, the USA, and in many other countries for oral treatment of schizophrenia and acute manic episodes in patients with bipolar disorder as well as for maintenance therapy to prevent recurrence in responders. The objective of the present study was to compare the pharmacokinetics of two 10 mg tablet formulations of Olanzapine following a single oral dose in healthy volunteers under fasting conditions, as per the European Medicine Agency (EMA) guidelines to grant marketing authorization.

Methods: This study was a randomized, open-label, two-treatment, two-period, two-sequences, single-dose, cross-over design with a washout period of 14 days. Both the test and the reference products were administered as 10 mg tablets with 240 mL of water after an overnight fast in each study period. A total of twenty blood samples were collected before dosing and within 144 hours after drug administration. Adverse events were monitored, recorded, and evaluated by investigators throughout the study.

Results: Of the 24 healthy adult male subjects enrolled, all of them completed both study periods. The geometric mean ratio 90% confidence intervals (CI) for fasting Cmax, AUC0-t, and AUC0-infinity were 94.83-113.71%, 95.04-105.69% and 95.94-107.00%, respectively. The 90% CI for the ratios of the three primary pharmacokinetic parameters (using log-transformed data) were within the range of 80-125%, meeting the regulatory criteria for bioequivalence.

Conclusions: The generic Olanzapine was bioequivalent to the reference formulation. It was well tolerated and provides an acceptable alternative to the reference drug.