5,6-Dihydro-5-Fluorouracil

5,6-Dihydro-5-Fluorouracil (5-DHFU; 5-Fluorodihydropyrimidine-2,4-dione) is the active metabolite of the thymidylate synthase inhibitor prodr_ug 5-fluorouracil (HY-90006), which is formed from 5-fluorouracil by dihydropyrimidine dehydrogenase (DPD). 5,6-Dihydro-5-Fluorouracil is cytotoxic to HaCaT keratinocytes (IC50=13.5 μM). Intravenous administration of 5,6-Dihydro-5-Fluorouracil (90 mg/kg/wk) in combination with 5-fluorouracil and the DPD inhibitor eniluracil (HY-10533) slows tumor growth in a rat colon cancer model.