<?xml version='1.0' encoding='UTF-8'?><xml><records><record><source-app name="HighWire" version="7.x">Drupal-HighWire</source-app><ref-type name="Journal Article">17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">KISANGA, ELTON RICHARD</style></author><author><style face="normal" font="default" size="100%">MELLGREN, GUNNAR</style></author><author><style face="normal" font="default" size="100%">LIEN, ERNST A.</style></author></authors><secondary-authors></secondary-authors></contributors><titles><title><style face="normal" font="default" size="100%">Excretion of Hydroxylated Metabolites of Tamoxifen in Human Bile and Urine</style></title><secondary-title><style face="normal" font="default" size="100%">Anticancer Research</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2005</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2005-11-01 00:00:00</style></date></pub-dates></dates><pages><style  face="normal" font="default" size="100%">4487-4492</style></pages><volume><style face="normal" font="default" size="100%">25</style></volume><issue><style face="normal" font="default" size="100%">6C</style></issue><abstract><style  face="normal" font="default" size="100%">The selective oestrogen-receptor modulator tamoxifen is the most commonly used drug against breast cancer. It has potent metabolites, such as 4-hydroxytamoxifen. Recently, the metabolite 4-hydroxy-N-desmethyltamoxifen has received increased attention as it may be a major contributor to the overall effects of tamoxifen. The excretion of tamoxifen and its metabolites was examined in a patient with biliary drainage after an oral dose of [14C]tamoxifen. During the first 10 days after oral dosing, 11.5, 26.7 and 24.7% of the radioactivity was excreted in the bile, urine and faeces, respectively. After deconjugation with beta-glucuronidase, the concentrations of tamoxifen and 4 of its metabolites were measured, and it was observed that the hydroxylated metabolites were excreted in the bile and urine. 4-Hydroxytamoxifen was the dominant compound, being detected during the first day of observation, whereas 4-hydroxy-N-desmethyltamoxifen was first observed in the urine and bile after 4 days. This is the first report on tamoxifen excretion in human bile and urine demonstrating that 4-hydroxytamoxifen may be a first-pass metabolite. In contrast, the potent metabolite 4-hydroxy-N-desmethyltamoxifen was first detected 4 days after administration of a single oral dose. Copyright© 2005 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved</style></abstract></record></records></xml>