Many migraine patients at risk for serotonin syndrome.

VIENNA -- An estimated 700,000 Americans were at risk for serotonin syndrome in 2004 because they were simultaneously on a triptan and a selective serotonin reuptake inhibitor or serotonin-norepinephrine reuptake inhibitor, according to data reported at the annual congress of the European College of Neuropsychopharmacology.

The figure of 700,000 at-risk individuals in 2004 is based on the most recently available data from the annual U.S. National Ambulatory Medical Care Survey. It predates the July 2006 Food and Drug Administration warning about the risk of potentially fatal serotonin syndrome resulting from coadministration of a triptan and an SSRI or SNRI, but the number of at-risk patients today is likely to be even larger--not smaller--than before the FDA warning, she added in an interview.

"The potential for coadministration could be even greater now, given how much the use of the SSRI and SNRI antidepressants has increased since 2004, along with the increase that's occurred in the use of triptans for treatment of migraine headaches," said Linda M. Robison of the pharmacoeconomics and pharmacoepidemiology research unit at Washington State University, Pullman.

Based on the weighted National Ambulatory Medical Care Survey data, an estimated 50.4 million Americans were prescribed an SSRI or SNRI in 2004, nearly 3.9 million patients were placed on a triptan, and 694,276 individuals were on both at the same time. In all, 84% were female, she reported.

Family physicians accounted for two-thirds of the physicians who prescribed a triptan and SSRI or SNRI; 19% were internists, 7.9% were neurologists, and 3.3% were psychiatrists.

Serotonin syndrome is caused by excessive stimulation of central and peripheral serotonin receptors. It results in motor, mental status, and autonomic changes that can range in severity from mild to fatal. Symptoms can include restlessness, loss of coordination, hypertension, hallucinations, tachycardia, fever, sweating, nausea and vomiting, overactive reflexes, and coma.

BY BRUCE JANCIN

Denver Bureau