| abstract |
xanthine derivatives, their preparation and their use as pharmaceutical compositions. the present invention relates to the substituted xanthines of the general formula (i), wherein r1 to r4 are defined as in claim 1, their tautomers and stereoisomers, their mixtures, their prodrugs and salts which have valuable pharmacological properties, particularly an inhibitory effect on the activity of the enzyme dipeptidyl peptidase-iv (dpp-iv). |