Validated UV Spectrophotometric Methods for the Estimation of Olanzapine in Bulk, Pharmaceutical Formulations and Preformulation Studies

Aims: To develop and validate two accurate and precise UV spectrophotometric methods for the estimation of widely prescribed anti psychotic drug-Olanzapine in bulk, formulations and preformulation studies.
Methodology: Two different solvent systems optimized for the analysis (100 mM hydrochloric acid with pH 1.2 and phosphate buffer saline with pH 7.4), were based on various criteria such as applicability of the method, sensitivity, ease of sample preparation, cost effectiveness, stability of drug in investigating medium, and reproducibility. Olanzapine was estimated at 258 nm in 100 mM hydrochloric acid and 252 nm in phosphate buffer saline.
Results: The linear regression equations obtained by applying least square regression analysis for Olanzapine were found to be: Absorbance = 0.0697 × concentration in µgml–1+ 0.008; r2= 0.9999) in 100 mM hydrochloric acid; absorbance = 0.0571 × concentration in µgml–1- 0.0052; r2 = 0.9998) in the phosphate buffer saline. Sandell’s sensitivity was found to be about 0.0144 µgcm−1 for hydrochloric acid and 0.0175 µgcm−1 for phosphate buffer saline. The apparent molar absorptivity was calculated to be 2.17x104mol−1cm−1 and 1.78x104 mol−1cm−1 in hydrochloric acid and phosphate buffer saline respectively.
Conclusion: Two spectrophometric methods for the analysis of Olanzapine have been developed successfully and validated as per ICH guidelines. Developed methods were successfully applied for the determination of Olanzapine in commercial tablets of varying strengths and various preformulation parameters of the drug such as dissociation constant.