April 21, 2010 -- An experimental migraine drug could help many patients who can't take or don't respond to current treatments, but questions remain about its safety.
Studies suggest that the drug telcagepant works in many people whose headache pain is not relieved with triptans, which are considered the most effective currently available drugs for treating migraines.
As many as a third of migraine sufferers fall into this category, according to one research analysis.
Since triptans cause the blood vessels to constrict, they may not be considered appropriate for use in people with heart disease or angina, history of stroke, uncontrolled high blood pressure, or pregnant women.
Telcagepant is a new type of migraine drug that blocks the calcitonin-gene-related peptide (CGRP) receptor.
In a review of investigational migraine treatments published today in The Lancet, migraine researchers Lars Edvinsson, MD, and Mattias Linde, MD, write that CGRP-targeting drugs may prove to be an important advance in migraine treatment.
But it is not clear if drugmaker Merck & Co., which developed telcagepant, will pursue regulatory approval for the drug due to concerns about its potential toxic effect on the liver.
Last spring, a phase II trial of telcagepant for the prevention of migraines was stopped early after several patients developed elevated liver enzymes indicative of possible liver damage.
When the treatment was stopped, liver enzyme levels returned to normal.
After meeting with regulatory authorities, Merck agreed to conduct an additional safety study of the drug.
Until that trial is completed, the company will not decide whether to seek approval for telcagepant as a migraine treatment, Merck spokeswoman Pam Eisele tells WebMD.
Edvinsson tells WebMD that with the exception of the unresolved questions about liver safety, the CGRP receptor blockers seem to have fewer troublesome side effects than triptans.
Some 28 million Americans have some experience with migraines, including 25% of women and 8% of men, according to the National Headache Foundation.
In some people, symptoms are limited to severe headache. In others, headaches are accompanied by nausea and vomiting, sensitivity to light and noise or visual displays preceding or during attacks known as aura.
Migraine specialist Stephen Silberstein, MD, tells WebMD that new drug treatments for migraine are definitely needed. But he adds that it is unlikely that a single drug or drug combination will be appropriate for all migraine sufferers.
Silberstein is a professor of neurology and directs the Jefferson Headache Center at Philadelphia's Thomas Jefferson University. He is also a past president of the National Headache Society.
"There are three important things to understand about migraine treatment," he says. "Drugs don't always work, when they work they don't work for everybody, and they usually have side effects."
He says promising nondrug treatments, such as a handheld device that zaps migraine pain, may be as important as new drugs.
Silberstein took part in a recent study of the portable device, known as single-pulse transcranial magnetic stimulation (sTMS).
Edvinsson has served as a paid consultant for Merck and several other drug companies.