title: Simultaneous determination of etoposide and its catechol metabolite in the plasma of pediatric patients by liquid chromatography/tandem mass spectrometry.
abstract: The anticancer drug etoposide is associated with leukemias with MLL gene translocations and other translocations as a treatment complication. The genotype of cytochrome P450 3A4 (CYP3A4), which converts etoposide to its catechol metabolite, influences the risk. In order to perform pharmacokinetic studies aimed at further elucidation of the translocation mechanism, we have developed and validated a liquid chromatography/electrospray/tandem mass spectrometry assay for the simultaneous analysis of etoposide and its catechol metabolite in human plasma. The etoposide analog teniposide was used as the internal standard. Liquid chromatography was performed on a YMC ODS-AQ column. Simultaneous determination of etoposide and its catechol metabolite was achieved using a small volume of plasma, so that the method is suitable for pediatric patients. The limits of detection were 200 ng ml(-1) etoposide and 10 ng ml(-1) catechol metabolite in human plasma and 25 ng ml(-1) etoposide and 2.5 ng ml(-1) catechol metabolite in protein-free plasma, respectively. Acceptable precision and accuracy were obtained for concentrations in the calibration curve ranges 0.2--100 microg ml(-1) etoposide and 10--5000 ng ml(-1) catechol metabolite in human plasma. Acceptable precision and accuracy for protein-free human plasma in the range 25--15 000 ng ml(-1) etoposide and 2.5--1500 ng ml(-1) etoposide catechol were also achieved. This method was selective and sensitive enough for the simultaneous quantitation of etoposide and its catechol as a total and protein-free fraction in small plasma volumes from pediatric cancer patients receiving etoposide chemotherapy. A pharmacokinetic model has been developed for future studies in large populations.
authors.affiliation: Center for Cancer Pharmacology, Department of Pharmacology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6160, USA.
authors.forename: S
authors.initials: S
authors.lastname: Pang
authors.forename: N
authors.initials: N
authors.lastname: Zheng
authors.forename: C A
authors.initials: CA
authors.lastname: Felix
authors.forename: J
authors.initials: J
authors.lastname: Scavuzzo
authors.forename: R
authors.initials: R
authors.lastname: Boston
authors.forename: I A
authors.initials: IA
authors.lastname: Blair
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000097:blood* / Q000493:pharmacokinetics; D001205:Ascorbic Acid / Q000737:chemistry; D002138:Calibration; D002396:Catechols / Q000097:blood* / Q000737:chemistry; D002648:Child; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics; D004355:Drug Stability; D005047:Etoposide / Q000097:blood* / Q000493:pharmacokinetics; D005838:Genotype; D006801:Humans; D016014:Linear Models; D013058:Mass Spectrometry / Q000379:methods*; D006899:Mixed Function Oxygenases / Q000235:genetics; D010084:Oxidation-Reduction; D011803:Quinine / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D002396:Catechols; D005047:Etoposide; D003577:Cytochrome P-450 Enzyme System; D011803:Quinine; D006899:Mixed Function Oxygenases; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D001205:Ascorbic Acid