Simultaneous Determination of Clopidogrel and Its Carboxylic Acid Metabolite (SR26334) in Human Plasma by LC-ESI-MS-MS: Application to the Therapeutic Drug Monitoring of Clopidogrel

A sensitive and specific liquid chromatography-tandem-mass spectrometry method was developed and validated for the simultaneous determination of clopidogrel and its carboxylic acid metabolite (SR26334) in human plasma using nateglinide and pioglitazone as internal standards. Analytes were extracted from 0.50 mL of plasma using diethyl ether-n-hexane (4:1, v/v). Chromatographic separation was performed on a Teknokroma C-18 column with a mobile phase of methanol-water (containing 0.1% formic acid) (80:20, v/v) at a flow rate of 0.20 mL min(-1) within 5.6 min. Linearity was established over the concentration range of 0.005-5 ng mL(-1) for clopidogrel and 20-2,500 ng mL(-1) for SR26334. Intra- and inter-batch standard deviations were less than 9.2% and the accuracy of this assay was found to fall within an acceptable range a parts per thousand currency sign10.0%. The method was successfully applied to the therapeutic drug monitoring of clopidogrel.