[Blood and tumor levels of tegafur, 5-fluorouracil, and uracil].

The blood and tissue concentrations of tegafur (TGF), 5-fluorouracil (5-FU) and uracil were tested by administering 6 capsules of UFT (600 mg as tegafur (TGF)) per day to 21 patients awaiting operation for stomach cancer. At the same time, comparative tests were performed by dividing the patients into two groups, giving UFT before meals in one group and in another after meals. Both 5-FU and uracil levels tend to reach to the maximum blood concentration after one hour, while showing similar variations with time lapse. Furthermore, a significantly positive relationship was observed between 5-FU and uracil in the rate of changes of blood concentration during six hours after administration of UFT. The 5-FU concentration within tumor tissue was 10 times higher than that within the blood and 2 times higher than that within normal tissue. A similar tendency was observed with uracil, which was of value in the clinical determination of the effect of uracil in inhibiting decomposition of 5-FU. With regard to the comparative test between the groups of pre- and post-meal UFT administration, the concentration of tegafur (TGF) and 5-FU in tumor tissue tended to be higher in the pre-meal group which indicates a need for further study of the phenomenon.