Composition for determining pyrimidine metabolizing activity

Abstract

The present invention provide a method for assessing the sensitivity to a pyrimidine drug such as 5-FU which is degraded in the pyrimidine metabolic pathway, specifically in vivo pyrimidine metabolizing activity, of an individual subject; and a preparation useful for the assessment. The present invention can be carried out by: administering a preparation comprising as an active ingredient a pyrimidine compound or its metabolite which acts as a substrate for a pyrimidine metabolizing enzyme, in which compound or metabolite at least one of C, O and N is labeled with an isotope; and assessing in vivo pyrimidine metabolizing activity based on the amount of excreted metabolite.

1 - 15 . (cancelled).  
     
     
         16 . A preparation for determining pyrimidine metabolizing activity, comprising at least one active ingredient selected from 5-fluorodihydrouracil, dihydrouracil, dihydrothymine, fluoro-β-ureidopropionic acid, β-ureidopropionic acid, β-ureidoisobutyric acid, in which at least one of C, O and N is labeled with a non-radioactive isotope selected from  13 C,  18 O and  15 N, respectively.  
     
     
         17 . The preparation according to  claim 16 , wherein the preparation has an oral dosage form.  
     
     
         18 . The preparation according to  claim 16 , wherein at least one of C and O is labeled with  13 C and  18 O, respectively.  
     
     
         19 . The preparation according to  claim 18 , wherein the preparation is designed for excreting a non-radioactive isotope-labeled CO 2  as expired air after administration.