title: [Assay method for uracil, dihydrouracil, 5-fluorouracil and 5-fluoro-5, 6-dihydrouracil by high-performance liquid chromatography].
abstract: In humans, 80-90% of the administered dose of 5-fluorouracil (5-FU) is degraded by dihydropyrimidine dehydrogenase (DPD), the initial rate-limiting enzyme in pyrimidine catabolism. In a previous report, the concentration ratio of uracil (U) and its dihydrogenated metabolite dihydrouracil (DHU) in human plasma before 5-FU treatment was found to be useful as an index of optimal 5-FU dosage, and was reported to be helpful in identifying patients with metabolic deficiency and anticipated risk of toxicity. We established an assay method for U, DHU, 5-FU and 5-fluoro-5,6-dihydrouracil (5-FDHU) in human serum and rat plasma using reverse-phase HPLC. After deproteinization of serum or plasma with perchloric acid, the supernatant was injected into HPLC with a column switching device and quantitated by UV detection. Separation was achieved by 3 columns whose characters were different and a mobile phase of 5 mmol/l sulfuric acid. In normal human serum, concentrations of U and DHU were 7.67-12.1 ng/ml and 70.4-103 ng/ml respectively, giving a DHU/U concentration ratio of 7.59-11.8. We determined U and DHU concentrations in rat plasma administered with 5-FU, and examined the correlation between DHU/U concentration ratio and DPD activity in the liver. Consequently, it was confirmed that U and DHU concentrations in rat plasma and DHU/U ratio were affected by 5-FU treatment. Also, there was a weakly significant, positive correlation between plasma DHU/U ratio and liver DPD activity (r = 0.44, p = 0.035). We expect that the serum DHU/U ratio obtained easily with this method can be utilized as a new index for safety with 5-FU treatment.
authors.affiliation: Pharmaceutical Research Institute, Kyowa Hakko Kogyo Co. Ltd.
authors.forename: Aki
authors.initials: A
authors.lastname: Nakamura
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kikuchi
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Ohishi
authors.forename: Taketoshi
authors.initials: T
authors.lastname: Masuike
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D042943:Dihydrouracil Dehydrogenase (NADP) / Q000378:metabolism; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood*; D006801:Humans; D008099:Liver / Q000201:enzymology; D008297:Male; D051381:Rats; D014498:Uracil / Q000031:analogs & derivatives* / Q000097:blood*
chemical_list: C007419:dihydrouracil; D014498:Uracil; C019389:5-fluorodihydrouracil; D042943:Dihydrouracil Dehydrogenase (NADP); D005472:Fluorouracil