title: Ultra-high performance liquid chromatography tandem mass spectrometric method for the determination of tamoxifen, N-desmethyltamoxifen, 4-hydroxytamoxifen and endoxifen in dried blood spots--development, validation and clinical application during breast cancer adjuvant therapy.
abstract: A LC-MSMS method for the simultaneous determination of tamoxifen, N-desmethyltamoxifen, 4-hydroxytamoxifen and endoxifen in dried blood spots samples was developed and validated. The method employs an ultrasound-assisted liquid extraction and a reversed phase separation in an Acquity(®) C18 column (150×2.1 mm, 1.7 µm). Mobile phase was a mixture of formic acid 0.1% (v/v) pH 2.7 and acetonitrile (gradient from 60:40 to 50:50, v/v). Total analytical run time was 8 min. Precision assays showed CV % lower than 10.75% and accuracy in the range 94.5 to 110.3%. Mean analytes recoveries from DBS ranged from 40% to 92%. The method was successfully applied to 91 paired clinical DBS and plasma samples. Dried blood spots concentrations were highly correlated to plasma, with rs>0.83 (P<0.01). Median estimated plasma concentrations after hematocrit and partition factor adjustment were: TAM 123.3 ng mL(-1); NDT 267.9 ng mL(-1), EDF 10.0 ng mL(-1) and HTF 1.3 ng mL(-1,) representing in average 98 to 104% of the actually measured concentrations. The DBS method was able to identify 96% of patients with plasma EDF concentrations below the clinical threshold related to better prognosis (5.9 ng mL(-1)). The procedure has adequate analytical performance and can be an efficient tool to optimize adjuvant breast cancer treatment, especially in resource limited settings.
authors.affiliation: Pós-graduação em Ciências Médicas, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil; Instituto de Ciências da Saúde, Universidade Feevale, Novo Hamburgo, RS, Brazil. Electronic address: marinaantunes@feevale.br.
authors.forename: Marina Venzon
authors.initials: MV
authors.lastname: Antunes
authors.affiliation: Instituto de Ciências da Saúde, Universidade Feevale, Novo Hamburgo, RS, Brazil.
authors.forename: Suziane
authors.initials: S
authors.lastname: Raymundo
authors.affiliation: Instituto de Ciências da Saúde, Universidade Feevale, Novo Hamburgo, RS, Brazil.
authors.forename: Vanessa
authors.initials: V
authors.lastname: de Oliveira
authors.affiliation: Instituto de Ciências da Saúde, Universidade Feevale, Novo Hamburgo, RS, Brazil.
authors.forename: Dilana Elisabeth
authors.initials: DE
authors.lastname: Staudt
authors.affiliation: Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Gössling
authors.affiliation: Instituto de Ciências da Saúde, Universidade Feevale, Novo Hamburgo, RS, Brazil.
authors.forename: Giovana Piva
authors.initials: GP
authors.lastname: Peteffi
authors.affiliation: Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil.
authors.forename: Jorge Villanova
authors.initials: JV
authors.lastname: Biazús
authors.affiliation: Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil.
authors.forename: José Antônio
authors.initials: JA
authors.lastname: Cavalheiro
authors.affiliation: Louvain Center for Toxicology and Applied Pharmacology, Université Catholique de Louvain, Brussels, Belgium.
authors.forename: Marie
authors.initials: M
authors.lastname: Tre-Hardy
authors.affiliation: Louvain Center for Toxicology and Applied Pharmacology, Université Catholique de Louvain, Brussels, Belgium.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Capron
authors.affiliation: Louvain Center for Toxicology and Applied Pharmacology, Université Catholique de Louvain, Brussels, Belgium.
authors.forename: Vincent
authors.initials: V
authors.lastname: Haufroid
authors.affiliation: Louvain Center for Toxicology and Applied Pharmacology, Université Catholique de Louvain, Brussels, Belgium.
authors.forename: Pierre
authors.initials: P
authors.lastname: Wallemacq
authors.affiliation: Pós-graduação em Ciências Médicas, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil; Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil.
authors.forename: Gilberto
authors.initials: G
authors.lastname: Schwartsmann
authors.affiliation: Instituto de Ciências da Saúde, Universidade Feevale, Novo Hamburgo, RS, Brazil.
authors.forename: Rafael
authors.initials: R
authors.lastname: Linden
mesh_terms: D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage / Q000097:blood*; D001711:Biotransformation; D001943:Breast Neoplasms / Q000097:blood* / Q000188:drug therapy / Q000473:pathology; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D059788:Dried Blood Spot Testing / Q000592:standards*; D016903:Drug Monitoring; D005260:Female; D006801:Humans; D057230:Limit of Detection; D059625:Liquid-Liquid Extraction; D008875:Middle Aged; D013010:Sonication; D013629:Tamoxifen / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood*; D053719:Tandem Mass Spectrometry
chemical_list: D018931:Antineoplastic Agents, Hormonal; D013629:Tamoxifen; C016601:afimoxifene; C055492:4-hydroxy-N-desmethyltamoxifen; C028787:N-desmethyltamoxifen
keywords: 4-Hydroxytamoxifen; Dried blood spot; Endoxifen; LC–MS/MS; N-desmethyltamoxifen; Tamoxifen