Drugs for ParkinsonÂ’s treatment may lead to heart damage

Two studies published in the New England Journal of Medicine have called into question the safety of two specific medications prescribed for Parkinson’s disease. The two drugs cited for safety concerns are Valeant Pharmaceuticals’ Permax (pergolide) and Pfizer’s Dostinex (cabergoline).  These drugs have been shown to lead to an increased risk of heart valve damage in Parkinson’s patients, but the new studies indicate that the risk of valve damage may actually be higher than what was previously thought.

In the first study, Italian researchers from the Istituti Clinici di Perfezionamento in Milan conducted an echocardiographic study of the prevalence of valvular abnormalities among 155 patients taking anti-Parkinson’s drugs and compared them to 90 control subjects. They conclude that the rate of serious valve regurgitation (irregular leaking of blood through faulty heart valves) was much higher in pergolide users (23 percent) and cabergoline users (29 percent) than in users of other Parkinson’s drugs (0 percent) or those not using any medication (6 percent).

The second study consisted of data from the United Kingdom General Practice Research Database, which was used by German scientists to identify 11,417 subjects, ages 40 to 80, who were prescribed anti-Parkinson’s drugs between 1988 and 2005. They found that cardiac-valve regurgitation was five times as likely in cabergoline patients and seven times as likely in patients taking pergolide.

Pergolide and cabergoline are included in a class of drugs known as ergot-derived dopamine agonists. The Italian study said that non–ergot-derived dopamine agonists did not appear to have the same damaging effects as pergolide and cabergoline. Currently, cabergoline is not approved for Parkinson’s treatment in the U.S., but it is prescribed for Parkinson’s treatment in other countries. Pergolide is also prescribed in the treatment of restless leg syndrome.

Permax is already sold with an FDA black-box warning on the label, noting the increased risk of heart valve damage. The Dostinex warning, instituted in December 2006, is not as strongly noted on its label. Once heart valves are damaged, the only recourse is valve replacement surgery, making the risks associated with the two drugs very significant.