title: Measurement of endogenous uracil and dihydrouracil in plasma and urine of normal subjects by liquid chromatography-tandem mass spectrometry.
abstract: A sensitive and specific HPLC-MS-MS method was developed for the determination of endogenous uracil (Ura) and its metabolite dihydrouracil (UH2) in human plasma and urine samples. Plasma samples were extracted with ethyl acetate-isopropanol (85:15, v/v) following added ammonium sulfate, and then separated on a Discovery Amide C16 column with 3% methanol solution as the mobile phase; urine samples were just centrifuged at 2500 g for detection. Quantitation was carried out by LC-MS-MS in the multiple reaction monitoring (MRM) mode. The limits of quantitation of the method for Ura and UH2 were 0.5 and 5 ng ml(-1) (for plasma), and 50 and 100 ng ml(-1) (for urine), respectively. This method can be useful to evaluate the activity of dihydropyrimidine dehydrogenase (DPD), a rate-limiting enzyme of the chemotherapy drug fluoropyrimidine, which will be helpful in investigating subject variation of DPD and adjusting clinical dosage in pyrimidine chemotherapy.
authors.affiliation: Clinical Pharmacology Research Center, Peking Union Medical College Hospital and Chinese Academy of Medical Sciences, Beijing, PR China. hjiang74@163.net
authors.forename: Hao
authors.initials: H
authors.lastname: Jiang
authors.forename: Ji
authors.initials: J
authors.lastname: Jiang
authors.forename: Pei
authors.initials: P
authors.lastname: Hu
authors.forename: Yufang
authors.initials: Y
authors.lastname: Hu
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D012016:Reference Values; D012680:Sensitivity and Specificity; D014498:Uracil / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine
chemical_list: C007419:dihydrouracil; D014498:Uracil