The present invention relates to the CGRP antagonists of general formula I wherein R1, R2, R3 and R4 are as defined in claim 1, the tautomers, the isomers, the diastereomers, the enantiomers, the hydrates thereof, the mixtures thereof and the salts thereof and the hydrates of the salts thereof, particularly the physiologically acceptable salts thereof with inorganic or organic acids or bases, as well as those compounds of general formula I wherein one or more hydrogen atoms are replaced by deuterium, pharmaceutical compositions containing these compounds, their use and processes for preparing them.