title: Sensitive HPLC-PDA determination of tamoxifen and its metabolites N-desmethyltamoxifen, 4-hydroxytamoxifen and endoxifen in human plasma.
abstract: A highly sensitive HPLC-UV method for the simultaneous determination of tamoxifen, N-desmethyltamoxifen, 4-hydroxytamoxifen and endoxifen in human plasma samples was developed and validated. The method employs a two step liquid-liquid extraction and a reversed phase separation on a Hypersil Gold(®) C18 column (150mm×4.6mm, 5μm) with isocratic elution. Mobile phase was a mixture of triethylammonium phosphate buffer 5mM pH 3.3 and acetonitrile (57:43, v/v). Total analytical run time was 16min. Precision assays showed CV % lower than 10.53% and accuracy in the range of 93.0-104.2%. The lower limits of quantification (0.75-8.5ngml(-1)) are adequate to measure clinically relevant concentrations in plasma samples. The method was successfully applied to 110 clinical plasma samples. Median plasma levels and interquartile range were: tamoxifen 55.77ngml(-1) (38.42-83.69ngml(-1)), N-desmethyltamoxifen 124.83ngml(-1) (86.81-204.80ngml(-1)), 4-hydroxytamoxifen 1.09ngml(-1) (0.76-1.53ngml(-1)) and endoxifen 6.18ngml(-1) (4.17-8.22ngml(-1)). The procedure has adequate analytical performance and can be employed in therapeutic drug monitoring of tamoxifen or pharmacokinetics studies.
authors.affiliation: Instituto de Ciências da Saúde, Universidade Feevale, Novo Hamburgo, Brazil; Programa de Pós-graduação em Ciências Médicas, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil. marinaantunes@feevale.br
authors.forename: Marina Venzon
authors.initials: MV
authors.lastname: Antunes
authors.forename: Daniela Dornelles
authors.initials: DD
authors.lastname: Rosa
authors.forename: Tamyris Dos Santos
authors.initials: Tdos S
authors.lastname: Viana
authors.forename: Huander
authors.initials: H
authors.lastname: Andreolla
authors.forename: Tiago Ozelame
authors.initials: TO
authors.lastname: Fontanive
authors.forename: Rafael
authors.initials: R
authors.lastname: Linden
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000097:blood* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D016903:Drug Monitoring / Q000379:methods; D005260:Female; D006801:Humans; D057230:Limit of Detection; D012680:Sensitivity and Specificity; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000097:blood* / Q000378:metabolism
chemical_list: D018931:Antineoplastic Agents, Hormonal; D013629:Tamoxifen; C016601:afimoxifene; C055492:4-hydroxy-N-desmethyltamoxifen; C028787:N-desmethyltamoxifen