title: Analysis of phase I and phase II metabolites of tamoxifen in breast cancer patients.
abstract: This study describes the application of LC/MS/MS to the determination of phase I and phase II metabolites of tamoxifen in urine and plasma samples of breast cancer patients. In the plasma extracts, in addition to the parent drug and N-desmethyltamoxifen, a minor metabolite tamoxifen N-oxide was identified for the first time in human. Four intact glucuronides of tamoxifen metabolites were isolated in the 24-hr posttreatment urine sample. They were the glucuronides of 4-hydroxytamoxifen, 4-hydroxy-N-desmethyltamoxifen, dihydroxytamoxifen, and a monohydroxy-N-desmethyltamoxifen. Hydroxylation followed by glucuronidation is a well-established metabolic route of tamoxifen, and this study describes for the first time direct analyses of these metabolites in human urine samples using on-line LC tandem MS.
authors.affiliation: Drug Development Section, Institute of Cancer Research, Sutton, Surrey, UK.
authors.forename: G K
authors.initials: GK
authors.lastname: Poon
authors.forename: Y C
authors.initials: YC
authors.lastname: Chui
authors.forename: R
authors.initials: R
authors.lastname: McCague
authors.forename: P E
authors.initials: PE
authors.lastname: Lłnning
authors.forename: R
authors.initials: R
authors.lastname: Feng
authors.forename: M G
authors.initials: MG
authors.lastname: Rowlands
authors.forename: M
authors.initials: M
authors.lastname: Jarman
mesh_terms: D001943:Breast Neoplasms / Q000097:blood / Q000378:metabolism* / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D013058:Mass Spectrometry; D013629:Tamoxifen / Q000097:blood / Q000378:metabolism* / Q000652:urine
chemical_list: D013629:Tamoxifen