In vivo 19F NMR comparative study of 5-fluorouracil, 1-(2-tetrahydrofuryl)-5-fluorouracil (FT) and an FT-uracil coadministration system in mouse tumors.

The suppression of alpha-fluoro-beta-alanine (FBAL) formation from 5-fluorouracil (FU) is an important subject in relation to tumor chemotherapy. This is the first comparative study of FU, 1-(2-tetrahydrofuryl)-5-fluorouracil (FT, a prodrug of FU) and of FT+uracil as a coadministration system (UFT) under an oral dose using the in vivo 19F NMR method. The slow release of FU from FT and the suppression of the catabolism of FU to FBAL in mouse livers and tumors by the coadministration of uracil with FT were demonstrated using consecutive NMR measurements. The applicability of the in vivo 19F NMR method to the drug evaluation in tumors and livers of small animals was successfully tested.