Two new studies published in today’s New England Journal of Medicine have called into question the safety of two specific medications prescribed for Parkinson’s disease. The two drugs cited–Valeant Pharmaceuticals’ Permax (pergolide) and Pfizer’s Dostinex (cabergoline)–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 be higher than 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 report 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).
In the second study, German scientists used data from the United Kingdom General Practice Research Database 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, citing the increased risk of heart valve damage. The Dostinex warning, instituted only last month, is not as strongly worded. Once heart valves are damaged, the only recourse is valve replacement surgery, making the risks associated with the two drugs quite significant.
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