Comparative study of 5-fluorouracil and its derivative, N1-(2'-tetrahydrofuryl)-5-fluorouracil on endogenous colony forming units in spleens of mice

The effect of intraperitoneal injection of N1-(2'-tetrahydrofuryl)-5-fluorouracil (FT-207) which is metabolized to 5-fluorouracil (5-FU) in vivo, on endogeneous colony forming units in the spleen (endogeneous CFU-s) was observed and compared with that of 5-FU. The 8 x 10-4m eqv of FT-207 injected in mice 20 minutes before x-rays irradiation of 450 rads suppressed the endogeneous CFU-s count to about 60% and about 5.5 x 10-5m eqv of 5-FU had the same effect. The suppression of FT-207 continued over 120 minutes and increased gradually. The effect of 5-FU was strong shortly after the injection but faded out for 120 minutes. FT-207 had almost no effect on the recovery constant (Blair) of endogeneous CFU-s for 3 days, whereas 5-FU reduced seriously, especially for the first 2 days. The differences in the effects of both compounds could not be explained on the base of the only differences in the metabolism of both compounds. (auth.)