Xanthine derivatives, the preparation thereof and their use as pharmaceutical compositions

摘要

The present invention relates to substituted xanthines of general formula 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).