PARKINSON'S DRUGS ASSOCIATED WITH HEART VALVE DAMAGE, STUDIES SHOW

Two drugs used to treat Parkinson's disease may increase the risk for heart valve damage, according to two studies published in the New England Journal of Medicine (NEJM).

Patients taking pergolide and cabergoline had a significantly higher risk of valvular heart disease than patients using other drugs, according to the two European studies. Pergolide, marketed as Eli Lilly's Permax, is also used to treat restless legs syndrome. Cabergoline, sold by Pfizer as Dostinex, is not approved to treat Parkinson's disease in the U.S., but is used for other conditions.

Both drugs are ergot-deprived dopamine agonists that activate a cellular receptor known as 5-HT2b. The two studies, published in the Jan. 4 NEJM, showed the drugs were associated with an increased risk in heart valve damage not seen in patients taking non-ergot-deprived dopamine agonists.

In the UK, researchers studied 11,417 patients taking at least two drugs to treat Parkinson's disease. According to the study, incidence rates of cardiac-valve regurgitation were significantly higher in patients taking pergolide and cabergoline than in patients taking other dopamine agonists or not taking one.

Patients taking pergolide had an incident rate of 30 cases per 10,000 patients, and cabergoline's rate was 33 cases per 10,000 patients, the study said. Among patients who did not receive a dopamine agonist, there was an incident rate of 5.5 cases per 10,000 patients.

In Italy, researchers studied 155 patients taking dopamine agonists for Parkinson's disease and 90 control subjects. Patients taking pergolide had a 23 percent rate of heart valve regurgitation, and those taking cabergoline had a 29 percent rate. The control subjects, who did not take any dopamine agonist, had a 6 percent rate.