title: Simultaneous determination of gemcitabine and its main metabolite, dFdU, in plasma of patients with advanced non-small-cell lung cancer by high-performance liquid chromatography-tandem mass spectrometry.
abstract: Gemcitabine, 2',2'-difluoro-2'-deoxycytidine (dFdC) is a pyrimidine antimetabolite employed against several human malignancies. It undergoes intracellular activation to the pharmacologically active triphosphate form (dFdCTP) and metabolic inactivation to the metabolite 2',2'-difluorodeoxyuridine (dFdU). In order to investigate the human plasma pharmacokinetics of dFdC and dFdU, we developed and validated an HPLC-MS/MS method, adding 2'-deoxycytidine as internal standard and simply precipitating the protein with acetonitrile. The method requires a small sample (125 microl), and it is rapid and selective, allowing good resolution of peaks from the plasma matrix in only 7 min. It is sensitive, precise and accurate, with overall precision, expressed as CV%, always less than 10.0% for both analytes and high recovery: > or = 80%. The limits of detection for dFdC and dFdU were 0.1 and 1.1 ng/ml, but considering the high concentrations in the plasma of patients investigated, we set the limit of quantitation at 20 ng/ml (0.08 microM) for dFdC and 250 ng/ml for dFdU, and validated the assay up to the dFdC concentration of 6.0 microg/ml (22.8 microM). The method was successfully used to study the drug pharmacokinetics in patients with advanced non-small-cell lung cancer in a phase II trial with gemcitabine administered as a fixed dose-rate infusion.
authors.affiliation: Laboratory of Cancer Pharmacology, Department of Oncology, Istituto di Ricerche Farmacologiche 'Mario Negri', via la masa 19, 20156 Milan, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Marangon
authors.forename: Federica
authors.initials: F
authors.lastname: Sala
authors.forename: Orazio
authors.initials: O
authors.lastname: Caffo
authors.forename: Enzo
authors.initials: E
authors.lastname: Galligioni
authors.forename: Maurizio
authors.initials: M
authors.lastname: D'Incalci
authors.forename: Massimo
authors.initials: M
authors.lastname: Zucchetti
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D002945:Cisplatin / Q000008:administration & dosage; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D005467:Floxuridine / Q000031:analogs & derivatives* / Q000097:blood; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; D005467:Floxuridine; D003841:Deoxycytidine; D002945:Cisplatin; C084565:2',2'-difluoro-2'-deoxyuridine; D000093542:Gemcitabine