title: High-performance liquid chromatographic assay with fluorescence detection for the simultaneous measurement of carboxylate and lactone forms of irinotecan and three metabolites in human plasma.
abstract: Irinotecan (CPT-11), a camptothecin analog, is metabolized to SN-38, an active topoisomerase I inhibitor, and inactive metabolites, including APC and SN-38 glucuronide (SN-38G). A high-performance liquid chromatographic assay method to simultaneously measure the lactone and carboxylate forms of CPT-11, SN-38, SN-38G, and APC in human plasma was developed. Chromatography was accomplished with a reversed-phase C(8) column and fluorescence detection. A gradient mobile phase system was used. The buffer for mobile phase A consisted of 0.75 M ammonium acetate, 5 mM tetrabutylammonium phosphate (pH 6.0), and acetonitrile (86:14, v/v). The buffer for mobile phase B was identical to mobile phase A with the exception of the concentration (50:50, v/v). Precipitation of plasma proteins was performed with cold methanol. The linear range of detection of the lactone and carboxylate forms of SN-38, SN-38G, and APC was 2-25 ng/ml, and 5-300 ng/ml for CPT-11. The limit of quantitation for the analytes ranged from 0.5 to 5 ng/ml. Analysis of patients' plasma samples obtained before and after CPT-11 administration showed that the assay is suitable for measuring lactone and carboxylate forms of CPT-11, SN-38, SN-38G, and APC in clinical studies.
authors.affiliation: Department of Pharmaceutical Sciences, Mail Stop 313, St. Jude Children's Research Hospital, 332 North Lauderdale, Memphis, TN 38105-2794, USA.
authors.forename: Thandranese S
authors.initials: TS
authors.lastname: Owens
authors.forename: Helen
authors.initials: H
authors.lastname: Dodds
authors.forename: Katrin
authors.initials: K
authors.lastname: Fricke
authors.forename: Suzan K
authors.initials: SK
authors.lastname: Hanna
authors.forename: Kristine R
authors.initials: KR
authors.lastname: Crews
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000097:blood* / Q000737:chemistry; D002138:Calibration; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000097:blood* / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D000077146:Irinotecan; D007783:Lactones / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D002264:Carboxylic Acids; D007783:Lactones; D000077146:Irinotecan; D002166:Camptothecin