November 24 (HealthDay News) -- A drug called telcagepant proved safe and effective in treating migraines and caused fewer side effects than the widely-used migraine drug zolmitriptan (Zomig), according to a study conducted by drug maker Merck & Co.

Zolmitriptan and other triptans are effective but can cause a number of side effects, including dizziness, tingling and numbness of the skin, chest discomfort, and throat tightness. In addition, triptans cause blood vessel narrowing and aren't recommended for patients with cardiovascular disease, high blood pressure and certain migraine subtypes, according to a news release about the study.

Telcagepant is from a different class, called calcitonin gene-related peptide (CGRP) antagonists. It's believed that brain concentrations of CGRP are elevated during a migraine. CGRP antagonists don't seem to have blood vessel narrowing properties and, therefore, may not carry the same cardiovascular-related risks as triptans.

This phase III study included 1,380 patients at 81 sites in Europe and the United States. The patients, who suffered from moderate or severe migraines, received either 150 milligrams or 300 milligrams of telcagepant, 5 milligrams zolmitriptan, or a placebo.

The 300-milligram dose of telcagepant was more effective than placebo for freedom from pain (27 percent of patients vs. 10 percent), pain relief (55 percent vs. 28 percent), absences of noise sensitivity (58 percent vs. 37 percent) and light sensitivity (51 percent vs. 29 percent), and nausea (65 percent vs. 55 percent), according to the study.

Telcagepant 300 milligram and zolmitriptan 5 milligram were similarly effective in treating migraines, and both were more effective than telcagepant 150 milligram. Negative side effects were reported by 31 percent of patients taking telcagepant 150 milligram, 32 percent taking placebo, 37 percent taking telcagepant 300 milligram, and 51 percent taking 5 milligram zolmitriptan.

"One potential benefit of the new CGRP receptor antagonist class of acute migraine treatments is the absence of vasoconstriction, a liability of the triptans, which may allow for the safe administration of telcagepant in patients with migraine with cardiovascular disease," the study authors wrote. "However, such patients were excluded from the present study because of the contraindication for zolmitriptan, and further studies are necessary to determine the safety of telcagepant in patients with cardiovascular disease. Additional studies are also necessary to assess the long-term efficacy and safety profile of telcagepant in patients treating more than one migraine attack."

The study was published online Nov. 25 and in an upcoming print issue of The Lancet. Preliminary results from the trial were presented in June at the American Headache Society's annual meeting, in Boston.

"This result marks a new era in migraine therapy. However, the remaining issue is to understand the site of action of the CGRP-receptor antagonists," Dr. Lars Edvinsson, of Lund University in Sweden, wrote in an editorial comment accompanying The Lancet study.

SOURCE: The Lancet, news release, Nov. 25, 2008