Telcagepant is an oral calcitonin-gene related peptide (CGRP) receptor 
antagonist that is being developed by Merck & Co Inc for the treatment of 
migraine. This compound blocks CGRP receptors and may block the dilation of 
dural vessels and reduce neurotransmission in the CNS, resulting in pain relief. 
Telcagepant does not cause vasoconstriction, one of the major limitations in the 
use of triptans, which are considered to be the standard of care for migraine. 
Data from phase II and III clinical trials suggest that the use of telcagepant 
for the acute treatment of migraine was comparable with the use of triptan 
compounds and was superior to placebo in all primary endpoints, including pain 
relief and freedom from pain at 2 h. However, recent data reported elevated 
transaminase levels when telcagepant was dosed daily rather than acutely. It was 
concluded that, if these hepatic toxicities are not observed in ongoing/future 
trials of the acute use of telcagepant, then this agent may offer an alternative 
to triptan therapy for the treatment of migraine.