The present invention relates to new CGRP-antagonists of general formulae Ia and Ib wherein R1, R2, R3, R4 and R5 are defined as mentioned below, the tautomers, the isomers, the diastereomers, the enantiomers, the hydrates, the mixtures and the salts thereof as well as the hydrates of the salts, particularly the physiologically acceptable salts thereof with inorganic or organic acids or bases, pharmaceutical compositions containing these compounds, the use thereof and processes for the preparation thereof.