title: Assay method for the carboxylic acid metabolite of clopidogrel in human plasma by gas chromatography-mass spectrometry.
abstract: This paper describes a GC-MS method for the analysis of the carboxylic acid metabolite (SR26334, II) of methyl (+)-(S)-alpha-(o-chlorophenyl)-6,7-dihydrothieno[3,2-c]pyridine-5( 4H)-acetate hydrogensulfate (clopidogrel, SR 25990, I) in plasma and serum. The analytical procedure involves a robotic liquid-liquid extraction with diethyl ether followed by a solid-liquid extraction on C18 cartridges. The derivatization process was performed using n-ethyl diisopropylethylamine and alpha-bromo-2,3,4,5,6-pentafluoro toluene. A structural analogue (III) of II, was used as internal standard. The 1/X2; weighted calibration curve obtained in the range 5-250 ng/ml was well described by a quadratic equation. The extraction efficiency was better than 48% over the range studied; for the internal standard it averaged 51% at 50 ng/ml. Precision ranged from 3.6 to 15.8%, and accuracy was between 92 and 114%. Dilution has no influence on the performance of the method which could then be used to quantitate plasma samples containing up to 25000 ng/ml. The limit of quantification was 5 ng/ml. The method validation results indicate that the performance characteristics of the method fulfilled the requirements for assay methods for use in pharmacokinetic studies.
authors.affiliation: Sanofi-Recherche, Montpellier, France.
authors.forename: P
authors.initials: P
authors.lastname: Lagorce
authors.forename: Y
authors.initials: Y
authors.lastname: Perez
authors.forename: J
authors.initials: J
authors.lastname: Ortiz
authors.forename: J
authors.initials: J
authors.lastname: Necciari
authors.forename: F
authors.initials: F
authors.lastname: Bressolle
mesh_terms: D002138:Calibration; D002264:Carboxylic Acids / Q000097:blood; D000077144:Clopidogrel; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D010975:Platelet Aggregation Inhibitors / Q000097:blood*; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D002264:Carboxylic Acids; D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine