NEW YORK: Two drugs used in the treatment of Parkinson's disease have been found to cause damage to heart valves.
According to two different studies, patients put on Eli Lily drug Permax and Pfizer drug Dostinex had shown higher risk of damage to the heart valve than those administered with other drugs.
One of the studies covered 11,417 patients in Britain and the other 245 patients in Italy. The results substantiate earlier findings that drugs that activate a cellular receptor called 5-HT2b could lead to damage of the heart valve.
Details of the studies have been published in the New England Journal of Medicine.
According to the British study, patients taking pergolide, which is the constituent drug in Eli Lily's Permax, were 7.1 times more likely to develop heart valve damage than those who had other treatments. Patients who had taken the highest doses had a 37 times greater risk.
Patients taking cabergoline, which is the basic drug in Pfizer's Dostinex, were 4.9 times more likely to develop heart valve damage. Higher doses put patients at 50.3 times higher risk.
Both these drugs are available in generic form.
In the second study, of the 245 people, 155 had Parkinson's disease. Of these, one group received pergolide, another cabergoline, a third an alternative treatment and the fourth none. It was revealed that 23.4 per cent of patients on pergolide and 28.6 per cent on cabergoline suffered heart damage, compared with just 5.6 per cent in the control group.
Permax is an approved drug in the United States and overseas for Parkinson's disease, while Dostinex is used for Parkinson's in other countries, while it is approved in the U.S. for a hormonal disorder, hyperprolactinemia. Permax already carries a black-box warning label -- the strongest warning required by the Food and Drug Administration -- about an increased risk of heart-valve problems since 2003. A milder warning is displayed in Dostinex packages since the last one month.
Dr Bryan L Roth, professor of pharmacology and medicinal chemistry at the University of North Carolina School of Medicine and director of the psychoactive drug screening program at the National Institute of Mental Health, who wrote an accompanying review on the articles in the journal, described the risk of valve disease “extraordinarily high.”
He said the drugs produced the same kind of valve damage caused by the weight loss combination fen-phen, which led to the withdrawal of two drugs, Pondimin and Redux, in 1997. The drugs lead to multiplication of cells in the heart valves, causing thickening of the valves and their dysfunction.
The British study was carried out by Dr Edeltraut Garbe of the Institute of Clinical Pharmacology, CharitA, University Medicine, Berlin and colleagues. The second study was conducted by Dr Renzo Zanettini of the Istituti Clinici di Perfezionamento, Milan.
Roth revealed that the drug Ecstasy, which is abused by drug addicts, has the potential to damage the heart in the same way. He said people who take Ecstasy on a regular basis may be at risk for this particular side effect.
