[Pharmacokinetic studies of a new fluorinated pyrimidine, 590-S (PH-FU), in human patients].

590-S (PH-FU) has a chemical structure of 1-(3-oxo-1, 3-dihydro-1-isobenzofranyl)-5-fluorouracil, which belongs to the fluorinated pyrimidine group. Preclinical studies of the drug revealed better a therapeutic index compared with that of Tegafur. The preclinical pharmacokinetic studies revealed a steep increase and rapid decrease of 590-S and activated 5-FU in the blood compared with those of other fluorinated pyrimidines. We performed pharmacokinetic studies on patients using oral administration of 590-S. The results indicated a steep increase and rapid decrease of 590-S and 5-FU in blood concentrations. Both substances were excreted in extremely small amounts into the urine and bile. In contrast to the blood concentrations, 590-S and 5-FU remained in the tissues for an extended period. The above results indicated that orally administered 590-S showed interesting pharmacokinetic characteristics which warrant further clinical studies.