title: Determination of topotecan in human and mouse plasma and in mouse tissue homogenates by reversed-phase high-performance liquid chromatography.
abstract: A sensitive and selective reversed-phase high-performance liquid chromatographic (HPLC) assay has been developed and validated for quantification of total topotecan in human and mouse plasma and in mouse tissue samples. Isocratic separation was achieved on a Zorbax SB-C(18) column and topotecan was monitored fluorimetrically. Two ranges of calibrations curves were used to determine lower levels of topotecan more accurately. Acceptable accuracy and precision was achieved for all matrices. Topotecan was stable upon repeated freeze-thawing for three cycles or storage for 24 h at ambient temperatures in spiked plasma samples and tissue homogenates, except in heart homogenates. In an additional validation experiment in which (14)C-labeled topotecan was administered to mice, the levels of unchanged topotecan were about 80-90% of the total radioactivity in tissue homogenates collected 10 min after drug administration and virtually similar as in plasma samples. However, results in tissue homogenates obtained 4 h post-drug administration indicated substantial metabolism of topotecan. This assay is suitable for studying the pharmacokinetics and tissue distribution of topotecan in mice. Our results demonstrate the importance of including all tissues of interest for pharmacokinetic studies in the validation procedure.
authors.affiliation: Department of Clinical Chemistry, The Netherlands Cancer Institute (Antoni van Leeuwenhoek Hospital), Plesmanlaan 121, Amsterdam, The Netherlands.
authors.forename: Nienke A
authors.initials: NA
authors.lastname: de Vries
authors.forename: Mariët
authors.initials: M
authors.lastname: Ouwehand
authors.forename: Tessa
authors.initials: T
authors.lastname: Buckle
authors.forename: Jos H
authors.initials: JH
authors.lastname: Beijnen
authors.forename: Olaf
authors.initials: O
authors.lastname: van Tellingen
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000097:blood / Q000302:isolation & purification* / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D004355:Drug Stability; D005240:Feasibility Studies; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D051379:Mice; D015394:Molecular Structure; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods; D013050:Spectrometry, Fluorescence / Q000295:instrumentation / Q000379:methods*; D014018:Tissue Distribution; D019772:Topotecan / Q000097:blood / Q000302:isolation & purification* / Q000493:pharmacokinetics*
chemical_list: D000970:Antineoplastic Agents; D019772:Topotecan