{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,7]],"date-time":"2026-10-07T23:11:05Z","timestamp":1791414665903,"version":"4.3.3"},"reference-count":59,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2012,3,27]],"date-time":"2012-03-27T00:00:00Z","timestamp":1332806400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biomedical Chromatography"],"published-print":{"date-parts":[[2013,1]]},"abstract":"<jats:title>ABSTRACT<\/jats:title><jats:p>The chemotherapeutic drug 5\u2010fluorouracil (5\u2010FU) is widely used for treating solid tumors. Response to 5\u2010FU treatment is variable with 10\u201330% of patients experiencing serious toxicity partly explained by reduced activity of dihydropyrimidine dehydrogenase (DPD). DPD converts endogenous uracil (U) into 5,6\u2010dihydrouracil (UH<jats:sub>2<\/jats:sub>), and analogously, 5\u2010FU into 5\u2010fluoro\u20105,6\u2010dihydrouracil (5\u2010FUH<jats:sub>2<\/jats:sub>). Combined quantification of U and UH<jats:sub>2<\/jats:sub> with 5\u2010FU and 5\u2010FUH<jats:sub>2<\/jats:sub> may provide a pre\u2010therapeutic assessment of DPD activity and further guide drug dosing during therapy. Here, we report the development of a liquid chromatography\u2013tandem mass spectrometry assay for simultaneous quantification of U, UH<jats:sub>2<\/jats:sub>, 5\u2010FU and 5\u2010FUH<jats:sub>2<\/jats:sub> in human plasma. Samples were prepared by liquid\u2013liquid extraction with 10:1 ethyl acetate\u20102\u2010propanol (v\/v). The evaporated samples were reconstituted in 0.1% formic acid and 10 \u03bcL aliquots were injected into the HPLC system. Analyte separation was achieved on an Atlantis dC<jats:sub>18<\/jats:sub> column with a mobile phase consisting of 1.0 m<jats:sc>m<\/jats:sc> ammonium acetate, 0.5 m<jats:sc>m<\/jats:sc> formic acid and 3.3% methanol. Positively ionized analytes were detected by multiple reaction monitoring. The analytical response was linear in the range 0.01\u201310 \u03bc<jats:sc>m<\/jats:sc> for U, 0.1\u201310 \u03bc<jats:sc>m<\/jats:sc> for UH<jats:sub>2<\/jats:sub>, 0.1\u201375 \u03bc<jats:sc>m<\/jats:sc> for 5\u2010FU and 0.75\u201375 \u03bc<jats:sc>m<\/jats:sc> for 5\u2010FUH<jats:sub>2<\/jats:sub>, covering the expected concentration ranges in plasma. The method was validated following the FDA guidelines and applied to clinical samples obtained from ten 5\u2010FU\u2010treated colorectal cancer patients. The present method merges the analysis of 5\u2010FU pharmacokinetics and DPD activity into a single assay representing a valuable tool to improve the efficacy and safety of 5\u2010FU\u2010based chemotherapy. Copyright \u00a9 2012 John Wiley &amp; Sons, Ltd.<\/jats:p>","DOI":"10.1002\/bmc.2741","type":"journal-article","created":{"date-parts":[[2012,3,27]],"date-time":"2012-03-27T20:09:59Z","timestamp":1332878999000},"page":"7-16","source":"Crossref","is-referenced-by-count":87,"title":["LC\u2010MS\/MS method for simultaneous analysis of uracil, 5,6\u2010dihydrouracil, 5\u2010fluorouracil and 5\u2010fluoro\u20105,6\u2010dihydrouracil in human plasma for therapeutic drug monitoring and toxicity prediction in cancer patients"],"prefix":"10.1002","volume":"27","author":[{"given":"Barbara","family":"B\u00fcchel","sequence":"first","affiliation":[{"name":"Institute of Clinical Chemistry, Inselspital Bern University Hospital, and University of Bern  INO\u2010F CH\u20103010 Bern Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peter","family":"Rhyn","sequence":"additional","affiliation":[{"name":"Institute of Clinical Chemistry, Inselspital Bern University Hospital, and University of Bern  INO\u2010F CH\u20103010 Bern Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stefan","family":"Sch\u00fcrch","sequence":"additional","affiliation":[{"name":"Department of Chemistry and Biochemistry University of Bern  Freiestrasse 3 CH\u20103012 Bern Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Claudia","family":"B\u00fchr","sequence":"additional","affiliation":[{"name":"Department of Chemistry and Biochemistry University of Bern  Freiestrasse 3 CH\u20103012 Bern Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ursula","family":"Amstutz","sequence":"additional","affiliation":[{"name":"Present address: Pharmaceutical Outcomes Programme, Division of Translational Therapeutics, Department of Pediatrics University of British Columbia, and Child and Family Research Institute  Vancouver Canada"},{"name":"Institute of Clinical Chemistry, Inselspital Bern University Hospital, and University of Bern  INO\u2010F CH\u20103010 Bern Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Carlo","family":"R. Largiad\u00e8r","sequence":"additional","affiliation":[{"name":"Institute of Clinical Chemistry, Inselspital Bern University Hospital, and University of Bern  INO\u2010F CH\u20103010 Bern Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2012,3,27]]},"reference":[{"key":"e_1_2_7_2_1","doi-asserted-by":"publisher","DOI":"10.1006\/abio.1996.9943"},{"key":"e_1_2_7_3_1","doi-asserted-by":"publisher","DOI":"10.2515\/therapie\/2010023"},{"key":"e_1_2_7_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.canlet.2006.09.006"},{"key":"e_1_2_7_5_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.jchromb.2009.07.004"},{"key":"e_1_2_7_6_1","doi-asserted-by":"publisher","DOI":"10.1002\/bmc.181"},{"key":"e_1_2_7_7_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.phrs.2004.01.006"},{"key":"e_1_2_7_8_1","first-page":"507","article-title":"Link between dihydropyrimidine dehydrogenase activity in peripheral blood mononuclear cells 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