title: Fast method for simultaneous quantification of tamoxifen and metabolites in dried blood spots using an entry level LC-MS/MS system.
abstract: The purpose of this study was to develop and validate a new liquid chromatography-tandem mass spectrometric (LC-MSMS) assay for the simultaneous quantification of tamoxifen (TAM) and its main therapeutically active metabolites, N-desmethyltamoxifen (NDT), 4-hydroxytamoxifen (4HT) and endoxifen (END) in dried blood spots. Ultrasound assisted methanolic extraction was used for TAM and metabolites extraction from dried blood spot. After evaporation and methanol reconstitution, the extract was injected into a LC-MSMS system. Reversed phase chromatography was performed on a C18 grafted column in gradient mode. TAM, metabolites, and internal standard (diazepam-d5; IS) were identified in positive electrospray ionization mode using m/z transition of 372.5>72.1 (TAM); 374.23>58.10 (END); 358.27>58.10 (NDT); 388.23>44.80 (4HT) and 290.00>198.00 (IS). Total analytical run time was 6.5min. Assay was linear from 1 to 500ng/mL for all substances and presented intra and inter-assay precision and accuracy <15%. TAM, NDT, 4HT and END limits of quantification and detection were of 1 and 0.5ng/mL; 1 and 3ng/mL; 1.7 and 3ng/mL; 0.6 and 2ng/mL, respectively. Recovery ranged from 83.8 to 96.3% with matrix effect ranged from 4.3 to 29.8% for TAM and its metabolites. Hematocrit value ≤40% appeared to negatively influence accuracy of the method. In conclusion, the method described here is somewhat accessible, relatively fast, sensitive and selective with no interference. This assay might be used to investigate the level of TAM and its metabolites in DBS for therapeutic drug monitoring purposes.
authors: Clinical Chemistry Department, Cliniques universitaires St Luc, Brussels, Belgium.
authors: Marie
authors: M
authors: Tré-Hardy
authors: Clinical Chemistry Department, Cliniques universitaires St Luc, Brussels, Belgium; Louvain Center for Toxicology and Applied Pharmacology, Université catholique de Louvain, UCL, Brussels, Belgium.
authors: Arnaud
authors: A
authors: Capron
authors: Instituto de Ciências da Saúde, Universidade Feevale, Novo Hamburgo, RS, Brazil.
authors: Marina Venzon
authors: MV
authors: Antunes
authors: Instituto de Ciências da Saúde, Universidade Feevale, Novo Hamburgo, RS, Brazil.
authors: Rafael
authors: R
authors: Linden
authors: Clinical Chemistry Department, Cliniques universitaires St Luc, Brussels, Belgium.
authors: Pierre
authors: P
authors: Wallemacq
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000097:blood*; D002853:Chromatography, Liquid / Q000295:instrumentation*; D059788:Dried Blood Spot Testing / Q000379:methods*; D016903:Drug Monitoring; D006801:Humans; D013629:Tamoxifen / Q000097:blood*; D053719:Tandem Mass Spectrometry / Q000295:instrumentation*
chemical_list: D018931:Antineoplastic Agents, Hormonal; D013629:Tamoxifen
keywords: Dried blood spot; Endoxifen; LC–MS/MS; Tamoxifen