Phenobarbital stimulates the induction of liver microsomal drug-metabolizing enzyme, namely, cytochrome P-450, which enhances the rate of conversion of FT-207 to 5-FU, the active substance. When FT-207 is administered in combination with phenobarbital to cancer patients, the fluctuation in level of the drug-metabolizing enzyme, cytochrome P-450, should be taken into consideration. Therefore, it was investigated whether the urinary level of D-glucaric acid could be of value as an indicator for

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... e evaluation of the activation of masked compounds, such as FT-207. The level of D-glucaric acid in urine was lower in cancer patients than in normal controls. The correlation between the level of urinary D-glucaric acid and that of 5-FU, which is an active metabolite of FT-207, in blood was statistically significant. The level of D-glucaric acid in urine was of use as an indicator for the evaluation of the activation of masked compounds, such as FT-207, in cancer chemotherapy. -urinary D-glucaric acid excretion; 1-(2