Abstract

An isocratic reverse phase high performance liquid chromatographic method with UV absorbance detection was developed for quantification of clozapine in rat serum. This method involves a single solvent extraction step with ethylacetate. Celecoxib served as the internal standard. The analytes were separated by HPLC using C18 Wakosil II RS (SGE) analytical column (5 μm particle size; 250'4.6 mm ID). Mobile phase comprised of methanol-water-triethylamine (75:25:0.5, v/v/v). The eluent was monitored at 254 nm by UV absorbance detection. Retention times of clozapine and celecoxib were 10.5 and 7.9 min, respectively. The mean absolute recovery value was about 75.8 to 79.9%,while the intra day and inter day coefficient of variation values were in the range of 2.1 to 5.7%.The calibration was linear over a concentration range of 100-4000 ng/ml. Accuracy ranged from 96.8 to 99.7%.The method was used to study the pharmacokinetics of clozapine after an intravenous bolus (10 mg/kg) and oral (20 mg/kg) administration of clozapine solution to rats.