[13C,15N2]-5-Fluorodihydrouracil

5-Fluorodihydrouracil is an active metabolite of the thymidylate synthase inhibitor prodrug 5-Fluorouracil. It is formed from 5-fluorouracil by dihydropyrimidine dehydrogenase (DPD). Intravenous administration of 5-fluorodihydrouracil (90 mg/kg per week), combined with 5-fluorouracil and the DPD inhibitor eniluracil, reduces tumor growth in a rat colon carcinoma model.

Stable isotope labeled [¹³C,¹⁵N₂]-5-Fluorodihydrouracil is intended for use as an internal standard for the quantification of 5-Fluorodihydrouracil by LC or GC-mass spectrometry.