In order to investigate the fate of 1-(2-tetrahydrofuryl)-5-fluorouracil (FT-207) in comparison with that of 5-fluorouracil tritiated FT-207 (3H-FT-207) and 5-fluovouracil (3H-5-fluorouracil)were administered from the rectum in normal and AH-130 tumor-bearing rats, and rapid absorption of 3H-FT-207 or 3H-5-fluorouracil, was observed. Blood level of radioactivity after rectal administration of 3H-FT-207 was higher and more continuous than that of 3H-5-fluorouracil. Although the radioactivity after rectal administration of 3H-FT-207 and 3H-5-fluovouracil was widely distributed in the various tissues of the animal with or without tumor, the highest concentration of the radioactivity was observed in the kidneys, and higher in tumor. The radioactivity in lymphatic gland reached a maximum level within 2-4 hr after the rectal administration of 3H-FT-207 and declined very slowly. The urinary excretion of radioactivity within 24 hr was about 30% of the administered dose of 3H-FT-207. More than 85% of the excreted radioactivity accounted for FT-207 and its metabolite, α-fluoro-β-alanine. Other metabolites such as 5-fluorouracil, α-fluoro-β-ureidopropionic acid and tritiated water were detected in small amounts in rat urine. The radioactivity in blood and tumor, 4 hr after rectal administration of 3H-FT-207, was found to represent FT-207. However, the radioactivity in liver was due to the presence of α-fluoro-β-alanine. About 90% radioactivity in lymphatic gland within 2-6 hr after rectal administration of 3H-FT-207 was detected as FT-207.
