abstract |
The present invention relates to substituted xanthines of general formula n n n n n n n n n n wherein R 1 to R 4 are defined as in claim 1 , the tautomers and the stereoisomers thereof, mixtures thereof, the prodrugs and the salts thereof which have valuable pharmacological properties, particularly an inhibiting effect on the activity of the enzyme dipeptidylpeptidase-IV (DPP-IV). |