Development and validation of high performance liquid chromatographic method for analysis of clozapine

In this study a rapid, simple and sensitive assay to quantify clozapine in human plasma by using reverse phase high performance liquid chromatographic method has been developed. Clozapine was extracted from human plasma using a mixture of chloroform: n-hexane 50:50 employing liquid-liquid extraction method. The calibration curve was found to be linear in the concentration range of 25-800 ng/ml. The inter day and intra day assay accuracy and precision fulfilled the criteria specified by USFDA, Guidance for industry: bioanalytical method validation. Clozapine was found to be stable in human plasma after 6 h incubation at room temperature, 50 days storage at -27°C and freeze thaw cycles, as well as after reconstitution with mobile phase after 24 h of storage in refrigerator. The validated method offers the advantage of using minimum injection volume (25μl) and plasma sample volume (300μl). The extraction method is simple and single step with no back extraction step, thus, making this method applicable to determination of pharmacokinetic profiles and parameters.