Excretion of 1-hexylcarbamoyl-5-fluorouracil in urine of mice.

Excretion and metabolites in urine and feces of mice after oral administration of l-hexylcarbamoyl-5-fluorouracil-6-14C (14C-HCFU) or 5-fluorouracil-6-14C (14C-FU) were examined. After oral administration, about 90% of 14C-HCFU was excreted in urine within 48 h but not in feces. Major radioactive compounds in urine were 1-(3-carboxypropylcarbamoyl)-5-fluorouracil (CPRFU), FU, 5, 6-dihydro-5-fluorouracil (DHFU) and alpha-fluoro-beta-alanine (FBAL). Excretion ratio of these metabolites within 48 h was 13.5, 32.5, 20.2 and 23.9%, respectively, CPRFU and FU were rapidly excreted in urine after 14C-HCFU administration followed by DHFU and FBAL. Excretion of the latter two degradation products of FU was slower. On the other hand, major metabolites in urine after 14C-FU administration were DHFU and FBAL, but intact FU was slightly excreted. Excretion ratio of FU, DHFU and FBAL within 48 h was 4.8, 58.1 and 28.2%, respectively.