UPDATE 1-Merck migraine drug matches Zomig in study

(Adds details, Merck comment, shares, byline)

By Ransdell Pierson

NEW YORK, June 27 (Reuters) - Merck & Co's (MRK.N) experimental treatment for migraine headaches provided similar pain relief to AstraZeneca PLC's (AZN.L) Zomig treatment in a late-stage study, but was better tolerated, Merck said on Friday.

Favorable phase 3 data for Merck's oral medicine telcagepant (formerly known as MK-974) were similar to those seen in earlier mid-stage studies. Merck plans to seek U.S. approval next year for the drug, which Cowen and Co believes could garner annual sales of $300 million by 2012, if it passes muster with regulators.

Telcagepant works through a new mechanism of action meant to avoid cardiovascular side effects -- including racing heartbeat and chest pains -- often seen with standard "triptan" treatments such as Zomig, GlaxoSmithKline Plc's (GSK.L) market-leading Imitrex and Merck's own Maxalt.

Merck said the trial pitted telcagepant against Zomig, rather than far-better-selling Imitrex, because the AstraZeneca drug is also considered a highly effective treatment.

Results of the new study were presented in Boston at the annual meeting of the American Headache Society.

Dr. Tony Ho, senior director of clinical neuroscience at Merck, said the trial was not designed to compare serious cardiovascular incidents, such as heart attacks.

But he said fewer less-serious cardiovascular problems often seen with triptans -- including chest pains and fatigue -- were seen with those taking telcagepant than those taking Zomig.