title: Quantitative determination of capecitabine and its six metabolites in human plasma using liquid chromatography coupled to electrospray tandem mass spectrometry.
abstract: Capecitabine is the oral prodrug of the anticancer drug 5-fluorouracil (5-FU). The purpose of this study was to quantify capecitabine and its metabolites including 5'-deoxy-5-fluorocytidine (5'-dFCR), 5'-deoxy-5-fluorouridine (5'-dFUR), 5-FU, dihydro-5-fluorouracil (FUH(2)), α-fluoro-ureidopropionic acid (FUPA) and fluoro-β-alanine (FBAL) in human plasma using liquid chromatography coupled to electrospray tandem mass spectrometry. To this end two individual assays were developed: one for the simultaneous quantification of capecitabine, 5'-dFCR and 5'-dFUR using reversed phase chromatography and gradient elution, and one assay for 5-FU, FUH(2), FUPA and FBAL using hydrophilic interaction chromatography and isocratic elution. Both assays were fully validated according to current FDA guidelines. Total run time for the capecitabine assay was 9.0min, and of the 5-FU assay 5.0min. Analyte extraction was performed by protein precipitation. Stable labeled isotopes for each of the analytes were used as internal standards. The linear ranges of the analytes were 50-6000ng/mL for the capecitabine assay and 50-5000ng/mL for the 5-FU assay. Validation results demonstrate that capecitabine and its metabolites can be rapidly, accurately, precisely and robustly quantified in human plasma with the presented methods. Both assays are currently in extensive use in support of pharmacokinetic studies in patients treated with capecitabine or 5-FU.
authors.affiliation: Division of Clinical Pharmacology, Department of Medical Oncology, The Netherlands Cancer Institute, PO Box 90203, 1006 BE Amsterdam, The Netherlands.
authors.forename: Maarten J
authors.initials: MJ
authors.lastname: Deenen
authors.forename: Hilde
authors.initials: H
authors.lastname: Rosing
authors.forename: Michel J
authors.initials: MJ
authors.lastname: Hillebrand
authors.forename: Jan H M
authors.initials: JH
authors.lastname: Schellens
authors.forename: Jos H
authors.initials: JH
authors.lastname: Beijnen
mesh_terms: D000069287:Capecitabine; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D004355:Drug Stability; D005472:Fluorouracil / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D006801:Humans; D016014:Linear Models; D013058:Mass Spectrometry / Q000379:methods; D011355:Prodrugs / Q000737:chemistry* / Q000378:metabolism / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D011355:Prodrugs; D003841:Deoxycytidine; D000069287:Capecitabine; D005472:Fluorouracil