[Pharmacokinetics of ftorafur-2-14C in rats with Walker carcinosarcoma]. / Farmakokinetika ftorafura-2-14C u krys s kartsinosarkomoi Uokera.

The pharmacokinetics of phthorafur-2-14C (Ph) was investigated after its intravenous injection to rats with Walker carcinosarcoma. The blood plasma level of Ph-2-14C and its metabolites proved to decrease in to a three-phase process. The content of the agent in the tissues decreased in the following sequence: the kidney, small intestine, tumour, stomach, muscle, heart, liver, lungs, spleen, brain and fat. The tumour was observed to contain Ph-2-14C and endogenous metabolite 5-phthoruracil-2-14C. Excretion of the agent continued for 48 hrs, 52.2% of the administered dose being eliminated via the urinary tract, 30% as 14CO2, and 0.8% in feces.

[Participation of non-specific rat liver microsome oxidases in destruction of Nl-furanidylpyrimidines]. / Uchastie nespetsificheskikh oksidaz mikrosom pecheni krys v razrushenii Nl-furanidilpirimidinov

N1-(3'-Butyrolactono)-5-fluorouracil, N1-(2'-furanidyl) 5-trifluoromethyluracil, N1-(2'-furanidyl)-5-fluoracil are split in the rat organism with the formation of free 5-fluorouracil. The destruction of the C--N bonds in the molecule of the N1-(2'-furanidyl)-5-fluoracil takes place in the liver microsomes. This process is strengthened by NADPH and weakened by SKF-525A. All the three furanidylpyrimidines studied induced differential spectra of type I in the suspension of the liver microsomes. This fact testifies to the interaction of these substances with the cytochrome P-450.

[Comparative study of the fate of fluorofur and 5-fluorouracil in the organism]. / Sravnitel'noe izuchenie sud'by ftorafura i 5-ftoruratsila v organizme

Fluorofur (FT) is slowly splitted in tissues releasing free 5-FU. The duration of stay in the organism of 5-FU formed from FT is longer than that of 5-FU administered solely. Moreover, FT does not result in the formation of such high 5-FU concentrations, as observed while using 5-FU itself. It seems to account for an insignificant toxicity of FT and its greater efficacy in treatment of malignant tumors.