title: Quantification of [3H]docetaxel in feces and urine: development and validation of a combustion method.
abstract: Most radiolabeled biological samples require extensive sample preparation to reduce quenching interference before quantification of radioactivity is possible. Clearly, a more rapid and simple method ensuring a constant count rate and optimal counting efficiency has important advantages. We report on the development and analytical method validation of a rapid and simple combustion method to quantify [3H]docetaxel excreted in human feces and urine. A 3-day validation procedure was performed; quality control (QC) samples, prepared in blank feces and urine, were combusted 5 times and aliquots of the produced tritiated combustion water were counted in a liquid scintillation counter. The validation runs demonstrated adequate precision (below 7.6%) across all QC levels. Sensitivity at the lowest QC level was excellent and recovery of radioactivity constant (ranging from 85 to 91.8%). Clinical applicability of the method was tested in a cancer patient receiving docetaxel and a tracer amount of [3H]docetaxel; during the first 72 h after [3H]docetaxel infusion, 60% of total radioactivity was excreted in the collected feces and urine, which is within the expected range. Combustion of tritiated feces and urine samples is a simple, rapid, sensitive, precise and reproducible method with high recovery. It can be applied to quantify [3H]docetaxel excretion after i.v. administration.
authors.affiliation: Department of Medical Oncology, Erasmus MC, Daniel den Hoed Cancer Center, Rotterdam, The Netherlands. f.engels@erasmusmc.nl
authors.forename: Frederike K
authors.initials: FK
authors.lastname: Engels
authors.forename: Dirk
authors.initials: D
authors.lastname: Buijs
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Loos
authors.forename: Jaap
authors.initials: J
authors.lastname: Verweij
authors.forename: Willem H
authors.initials: WH
authors.lastname: Bakker
authors.forename: Eric P
authors.initials: EP
authors.lastname: Krenning
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage / Q000378:metabolism* / Q000493:pharmacokinetics / Q000652:urine; D000077143:Docetaxel; D005243:Feces / Q000737:chemistry*; D006801:Humans; D007262:Infusions, Intravenous; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism; D015203:Reproducibility of Results; D012588:Scintillation Counting / Q000379:methods*; D043823:Taxoids / Q000008:administration & dosage / Q000378:metabolism* / Q000493:pharmacokinetics / Q000652:urine; D014316:Tritium
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D043823:Taxoids; D014316:Tritium; D000077143:Docetaxel