The present invention relates to 2-amino-imidazo[4,5-d]pyridazin-4-ones
and 2-amino-imidazo[4,5-c]pyridin-4-ones of general formula 1
wherein R.sup.1 to R.sup.4 and X are defined as in claims 1 to 6, the
tautomers, the enantiomers, the diastereomers, the mixtures thereof and
the salts thereof, which have valuable pharmacological properties,
particularly an inhibiting effect on the activity of the enzyme
dipeptidylpeptidase-IV (DPP-IV).