[Study of tissue drug concentration of fluorinated pyrimidine anticancer drugs--comparison of 5'DFUR and UFT]

In order to verify the tumor-selective toxicity of fluorinated pyrimidine anticancer drugs, we conducted an investigation of the clinical pharmacology of two of these drugs, 5'DFUR and UFT. 5'DFUR was administered to 8 patients and UFT to 8 other patients in respective dosages of 800-1,000 mg/day and 400-600 mg/day an average of 6 days before the patients underwent surgery for cancer of the large bowel, and the concentrations of these drugs in tissue were then measured. No 5'DFUR whatsoever was detected in serum, the lymphnodes, normal large bowel tissue, or cancerous large bowel tissue after administration of this drug. Moreover, levels of the active substance, 5-FU, after administration of 5'-DFUR were low in serum, the lymphnodes, normal large bowel tissue (0.033 +/- 0.024 microgram/g), and cancerous large bowel tissue (0.034 +/- 0.020 microgram/g), and no difference was observed between normal and cancerous large intestine tissue. On the other hand, tegafur was detected in all of the tissues following the administration UFT, and the concentration of 5-FU was significantly high, particularly in cancerous large bowel tissue (0.108 +/- 0.057 microgram/g) compared to normal sites (0.044 +/- 0.048 microgram/g) (p less than 0.05). The above results indicate that UFT is a promising drug for use in chemotherapy for cancer of the large bowel.