CGRP receptor antagonists in the treatment of migraine

Calcitonin gene-related peptide (CGRP) is a potent neuropeptide that is expressed in the trigeminovascular system (TGVS) and plays a pivotal role in migraine pathophysiology. Inhibition of CGRP effects via CGRP receptor blockade is one of the mechanisms that can be used in anti-migraine therapy. Two types of CGRP receptor antagonists have been studied: both telcagepant and olcegepant are modified dipeptides that have high binding affinity for the CGRP receptor. In phase II and III clinical trials CGRP receptor blockade has been shown to be an effective acute migraine therapy without direct vasoconstrictive effects. Due to olcegepant's very low biological availability after oral intake, the clinical use of this compound is limited. Therefore, telcagepant will probably be the first CGRP receptor antagonist available for migraine treatment. The prospect of a non-vasoconstrictive treatment offers new therapeutic alternatives. CGRP receptor antagonist might be a therapeutic option in patients that can not use triptans due to increased cardiovascular risk profiles, in patients who suffer from triptan side-effects, or in patients who do not respond well (enough) to triptans.