Liquid chromatographic–tandem mass spectrometric assay for the simultaneous quantification of Camptosar ® and its metabolite SN-38 in mouse plasma and tissues

• Published in: Journal of Chromatography A 2005-05, Vol.1073 (1), p.249-255
• Main Authors: Bardin, Sofia, Guo, Wei, Johnson, Jenifer L., Khan, Sumsullah, Ahmad, Ateeq, Duggan, Jeffrey X., Ayoub, Jennifer, Ahmad, Imran
• Format: Article
• Language: English
• Subjects: Analysis; Animals; Antineoplastic Agents, Phytogenic - blood; Antineoplastic Agents, Phytogenic - pharmacokinetics; Biological and medical sciences; Camptothecin; Camptothecin - analogs & derivatives; Camptothecin - blood; Camptothecin - pharmacokinetics; Chromatography, High Pressure Liquid - methods; CPT-11; General pharmacology; Irinotecan; Liquid chromatography; Mass Spectrometry - methods; Medical sciences; Mice; Pharmacokinetics; Pharmacology. Drug treatments; Reference Standards; Reproducibility of Results; Sensitivity and Specificity; SN-38; Tandem mass spectrometry; Tissue Distribution
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2004.08.060

A simple, rapid and sensitive LC–MS/MS bioanalytical method has been developed to simultaneously quantify Camptosar (CPT-11) and its active metabolite, SN-38, in mouse plasma and tissues. A single step protein precipitation with acetonitrile in 96-well plates was used for sample preparation. Camptothecin (CPT) was used as the internal standard. Fast separation of SN-38, CPT-11 and CPT was carried out isocratically on a C 18, 2 mm × 50 mm, 5 μm HPLC column with a mobile phase containing acetonitrile and 20 mM ammonium acetate (pH 3.5) and a 2.5 min chromatographic run time. The API 4000 MS/MS system was operated in positive ionization multiple reaction monitoring mode, and the transitions for SN-38, CPT-11 and CPT were 393.4 → 349.3, 587.6 → 167.2 and 349.3 → 305.3, respectively. The SN-38 and CPT-11 concentrations in samples were calculated from a standard curve of peak area ratios of the analyte to that of the internal standard using a 1/ x 2 weighted linear regression. The quantitation limit of 0.5 ng/mL was achieved by using a low sample volume (100 μL) of plasma or tissue homogenates. The assay was linear over the concentration range of 0.5–500 ng/mL with acceptable precision and accuracy. The method was used for the quantification of CPT-11 and SN-38 in plasma and tissues to support a preclinical pharmacokinetics and tissue distribution study of CPT-11 in mice.