Evaluation of Bioequivalence of Two Oral Formulations of Olanzapine

Olanzapine is an atypical antipsychotic drug, used for the management of schizophrenia and for the treatment of moderate to severe mania associated with bipolar disorder. The objective of the present randomised, crossover study was to compare the bioavailability of olanzapine 10 mg/5 ml powder for oral suspension with olanzapine 10 mg orally disintegrating tablet. Eighteen healthy male volunteers were randomly assigned to crossover, single-dose treatment regimens. Serial blood samples were collected, and plasma concentrations of olanzapine were analysed using the LC-MS/MS technique. Pharmacokinetic parameters and bioequivalence limits were calculated using non-compartmental methods. Average C_max following administration of the single 10 mg disintegrating tablet formulation and 10 mg/5 ml suspension were 14.47±4.25 ng/ml and 13.56±3.99 ng/ml respectively. Corresponding median T_max were 5.0 h and 6.0 h, respectively. The average AUC_0–t values and AUC_0–inf values were similar following each of the olanzapine preparations. Overall, the 90% Confidence Interval for the intra-individual ratios of the log-transformed C_max and AUC values of the two formulations were within the bioequivalence interval of 80–125%. The study has demonstrated the bioequivalence of the 10 mg tablet and the 10 mg/5 ml oral suspension of olanzapine.