[Level of 5-FU in cancerous and normal tissues of nude mice after oral administration of tegafur coadministered with uracil (UFT)].

In order to investigate the effect of UFT, a new antitumor agent, 5-fluorouracil (5-FU) levels in serum and various tissues were measured by the gas chromatographic-mass fragmentographic method. The subjects used for the study were nude mice which had received implants of human endometrial carcinoma. The results were as follows: As compared with tegafur, the concentration of 5-FU in serum rose quickly when UFT was administered, and the values were clearly high. The concentration of 5-FU obtained in tumor tissues with the use of UFT were 2.5 times higher than those obtained by the use of tegafur. Even with one third of the dose of UFT, values were still 1.5 times higher. In normal tissues, the administration of UFT against that of tegafur resulted in higher concentrations of 5-FU. On the other hand, when one third of the dose of UFT was used, 5-FU concentrations in major organs, such as the liver or kidney, showed clearly low values. Based on these findings, it became clear that the 5-FU concentration in tumor tissue is specifically raised by tegafur coadministered with Uracil (UFT), while such an effect is prevented from proceeding in normal tissue.