Clinical results from a phase II study presented for the first time at the American Headache Society (AHS) annual meeting showed that MK-0974, an investigational oral calcitonin gene-related peptide (CGRP) receptor antagonist, significantly improved migraine pain relief two hours after dosing compared to placebo, and the relief was sustained through 24 hours.

MK-0974 was generally well tolerated in the study. Responses specific to other measures, such as migraine-associated symptoms, functional disability and use of additional rescue medications also were reported. MK-0974 is Merck's investigational medicine in phase III clinical development for the acute treatment of migraine in adults and, if approved, may be the first in a new class of migraine treatments since the approval of the first triptan drug in 1991.

"The findings of this early-stage trial demonstrate the therapeutic potential of MK-0974 for the acute treatment of migraines," said Tony Ho, M.D., senior director of clinical Neuroscience, Merck Research Laboratories. "Larger clinical trials, such as those now underway, will provide more insight into the efficacy and safety profile of MK-0974."

MK-0974 is an antagonist of the receptor for CGRP, a primary neuropeptide involved in the pathophysiology of migraine. CGRP and its receptors are found in areas of the central and peripheral nervous system that are important for the transmission of migraine pain. During migraine attacks, CGRP activates these receptors and facilitates the transmission of pain impulses. MK-0974 blocks the binding of CGRP to receptors within these areas and thereby is believed to inhibit the transmission of pain signals that lead to migraine headaches.