Some Restless Legs Medications can cause Valvular Dysfunction

Two case-control studies published simultaneously in the January 4 issue of The New England Journal of Medicine provide some of the strongest evidence that treatment with the ergot-derived dopamine antagonists pergolide and cabergoline, commonly used in Parkinson's disease, can cause cardiac-valve dysfunction. They also suggest that the adverse effect is not caused by some other prescribed dopamine antagonists, especially those not derived from ergot.
According to a perspective by Bryan L. Roth, MD, PhD, of the University of North Carolina in Chapel Hill, that accompanies the 2 studies, the findings support prior clinical and mechanistic evidence for a link between a histologically distinct fibrotic valvulopathy and treatment with drugs that block the serotonin receptor 5-hydroxytryptamine 2B (5-HT2B). Pergolide and cabergoline have that biochemical action in common, whereas the other studied dopamine antagonists do not have significant effects on 5-HT2B, writes Dr. Roth.
Dopamine agonists are used to treat both Parkinson's disease and restless legs syndrome. The association between ergot-derived dopamine agonists and valvular dysfunction was first recognized about 5 years ago. Requip and Mirapex are the only dopamine agonists that should be used to treat restless legs syndrome.