title: Validated GC/MS method for the simultaneous determination of clozapine and norclozapine in human plasma. Application in psychiatric patients under clozapine treatment.
abstract: A sensitive and specific GC/MS method for the determination of clozapine (CLZ) and its major metabolite norclozapine (NCLZ), in plasma has been developed, optimized and validated. Specimen preparation includes solid-phase extraction of both analytes using Bond-Elut Certify cartridge and further derivatization with TFAA. Clozapine-d8 was used as internal standard for the determination of CLZ and NCLZ. Limits of detection were 0.45 ng/mL for CLZ and 1.59 ng/mL for NCLZ, while limits of quantification were 1.37 ng/mL for CLZ and 4.8 ng/mL for NCLZ, as calculated by the calibration curves. The calibration curves were linear up to 600 ng/mL for CLZ and NCLZ. Absolute recovery ranged from 82.22% to 95.35% for both analytes. Intra- and interday accuracy was less than 7.13% and --12.52%, respectively, while intra- and interday precision was between 9.47% and 12.07%, respectively, for CLZ and NCLZ. The method covers all therapeutic range and proved suitable for the determination of CLZ and NCLZ not only in psychiatric patients but also in forensic cases with clozapine implication.
authors.affiliation: Department of Forensic Medicine and Toxicology, School of Medicine, University of Athens, Athens 11527, Greece.
authors.forename: I
authors.initials: I
authors.lastname: Vardakou
authors.forename: A
authors.initials: A
authors.lastname: Dona
authors.forename: C
authors.initials: C
authors.lastname: Pistos
authors.forename: G
authors.initials: G
authors.lastname: Alevisopoulos
authors.forename: S
authors.initials: S
authors.lastname: Athanaselis
authors.forename: C
authors.initials: C
authors.lastname: Maravelias
authors.forename: C
authors.initials: C
authors.lastname: Spiliopoulou
mesh_terms: D003024:Clozapine / Q000031:analogs & derivatives* / Q000097:blood*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D016014:Linear Models; D001523:Mental Disorders / Q000097:blood / Q000188:drug therapy; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction
chemical_list: C058272:norclozapine; D003024:Clozapine