title: Evaluation of tamoxifen and metabolites by LC-MS/MS and HPLC methods.
abstract: Epidemiological and laboratory evidence suggests that quantification of serum or plasma levels of tamoxifen and its metabolites, 4-hydroxy-N-desmethyl-tamoxifen (endoxifen), Z-4-hydroxytamoxifen (4HT), N-desmethyl-tamoxifen (ND-tam), is a clinically useful tool in the assessment and monitoring of breast cancer status in patients taking adjuvant tamoxifen. A liquid chromatographic mass spectrometric method (LC-MS/MS) was used to measure the blood levels of tamoxifen and its metabolites. This fully automated analytical method is specific, accurate and sensitive. The LC-MS/MS automated technique has now become a widely accepted reference method. This study analysed a randomly selected batch of blood samples from participants enrolled in a breast cancer study to compare results from this reference method in 40 samples with those obtained from a recently developed high-performance liquid chromatography (HPLC) method with fluorescence detection. The mean (SD) concentrations for the LC-MS/MS method (endoxifen 12.6 [7.5] ng/mL, tamoxifen 105 [44] ng/mL, 4-HT 1.9 [1.0] ng/mL, ND-tam 181 [69] ng/mL) and the HPLC method (endoxifen 13.1 [7.8] ng/mL, tamoxifen 108 [55] ng/mL, 4-HT 1.8 [0.8] ng/mL, ND-tam 184 [81] ng/mL) did not show any significant differences. The results confirm that the HPLC method offers an accurate and comparable alternative for the quantification of tamoxifen and tamoxifen metabolites.
authors.forename: D D
authors.initials: DD
authors.lastname: Heath
authors.forename: S W
authors.initials: SW
authors.lastname: Flat
authors.forename: A H B
authors.initials: AH
authors.lastname: Wu
authors.forename: M A
authors.initials: MA
authors.lastname: Pruitt
authors.forename: C L
authors.initials: CL
authors.lastname: Rock
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000097:blood*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002853:Chromatography, Liquid; D005453:Fluorescence; D006801:Humans; D013058:Mass Spectrometry; D013629:Tamoxifen / Q000097:blood*
chemical_list: D018931:Antineoplastic Agents, Hormonal; D013629:Tamoxifen