WEDNESDAY, Jan. 3, 2007 (HealthDay News) -- Two drugs commonly used to treat Parkinson's disease can cause harm to heart valves, according to two studies in the Jan. 4 New England Journal of Medicine.
The drugs, pergolide and cabergoline, are both from a class of medications called "ergot-derived dopamine receptor agonists." Ergot is a fungus, and ergot-derived drugs are used not only in the treatment of Parkinson's but also for restless leg syndrome and migraine headaches.
Ergot-derived dopamine receptor agonists were also in the now banned diet drug Fen-phen -- also associated with heart valve disease.
"We uncovered the biomedical reason why Fen-phen had particular side effects on the heart," said Dr. Bryan L. Roth, of the Department of Pharmacology at the University of North Carolina and author of an accompanying journal editorial.
"We evaluated other medications and predicted that they would have the same side effect on the heart," he said. "Our predictions were verified in these two studies."
Based on the new findings, Roth wants the U.S. Food and Drug Administration to look at all drugs that have this side effect with an eye to banning pergolide (brand named Permax) and cabergoline (Dostinex). "This side effect is very dangerous," he said. "It could result in an individual's death or undergoing valve replacement surgery," he added.
These types of drugs interact with a receptor in the heart valve, causing the valve to overgrow and become floppy and leaky, Roth explained.
In the first report, Dr. Edeltraut Garbe, from the Institute of Clinical Pharmacology, Charite, University Medicine, Berlin, and colleagues collected data on more than 11,000 people 40 to 80 years of age who were taking anti-Parkinson's drugs between 1988 and 2005.
The researchers found that, among 31 patients with newly diagnosed cardiac valve problems, six were taking pergolide, six were taking cabergoline, and 19 had not taken any dopamine agonist in the past year.
Almost 30 percent of the patients taking pergolide or cabergoline were at increased risk for heart valve problems.
"In this study, use of the dopamine agonists pergolide and cabergoline was associated with an increased risk of newly diagnosed cardiac-valve regurgitation," the authors concluded.
In the second study, a team of Italian researchers led by Dr. Renzo Zanettini, from the Istituti Clinici di Perfezionamento, Milan, studied 155 patients taking dopamine agonists for Parkinson's disease. Among these patients, 64 were taking pergolide, 49 were taking cabergoline, and 42 were taking non-ergot-derived dopamine agonists. In addition, there were 90 controls.
Zanettini's group found that about 23 percent of the patients taking pergolide had heart valve problems, as did about 29 percent of the patients taking cabergoline.
In contrast, none of the patients taking non-ergot-derived dopamine agonists had a heart problem, while 5.6 percent of the control patients did.
In addition, patients who took higher doses of pergolide or cabergoline had more advanced heart valve disease, the researchers reported.
"The frequency of clinically important valve regurgitation was significantly increased in patients taking pergolide or cabergoline, but not in patients taking non-ergot-derived dopamine agonists, as compared with control subjects," the researchers wrote. "These findings should be considered in evaluating the risk-benefit ratio of treatment with ergot derivatives," they concluded.
"If you have Parkinson's, you need to find out from your doctor if you're taking a medication that could cause this risk of serious heart damage," Roth said. "I would recommend not prescribing these medications at all. Our hope is that these two studies will encourage the FDA to remove these drugs from use."
Roth also noted that the drug Ecstasy also has the potential to damage the heart in the same way. "People who take Ecstasy on a regular basis may be at risk for this particular side effect," he said.
In a related story, a new drug to treat early Parkinson's, called transdermal rotigotine, has shown in a phase 3 clinical trial that it is safe and effective, according to a report in Neurology.
Rotigotine is a non-ergot-derived dopamine receptor agonist delivered via a patch designed for once-a-day application. The drug is currently being reviewed by the FDA. It is currently marketed in Europe as therapy for early-stage Parkinson's and has received a favorable review for advanced-stage Parkinson's, according to the German drug company Schwarz Pharma, the maker of rotigotine.
There's more on Parkinson's disease at the U.S. National Institute of Neurological Disorders and Stroke.