Parkinson's Drugs: Heart Damage Link?
Researchers Raise Concerns About Damage to Heart Valves From 2 Parkinson's Drugs
Checking for Heart Valve Disease continued...
Clinically important evidence of valve damage was seen in roughly 5% of the comparison group, compared with 23% of patients taking pergolide and 28% of patients taking cabergoline.
Garbe says it is clear from the two studies that patients taking either pergolide or cabergoline should be monitored closely for heart valve damage.
"We aren't saying that these drugs should not be used," she says. "I think if patients are appropriately followed they can be prescribed. But neurologists and other treating physicians have to be made aware of the risks."
A spokesman for pergolide manufacturer Valeant Pharmaceuticals International tells WebMD that the company would have no direct comment on the two new studies. But a company statement reaffirmed the safety of the drug.
"Permax (pergolide) is a safe and effective treatment for patients with Parkinson's disease," the statement reads. "Although Valeant no longer promotes the product, we still make it available for those who prescribe it. We also routinely communicate with the FDA and recently worked with the agency to modify the label to advise physicians that the product, like other dopamine agonists, should be used with caution."
Bryan Roth, MD, PhD, tells WebMD that the two Parkinson's drugs appear to cause heart damage in the same way that the now notorious weight lossmedication fen-phen did.
Fen-phen was voluntarily withdrawn from the market a decade ago, following reports of life-threatening heart valve disease. Another related diet drug marketed by Wyeth-Ayerst Laboratories as Redux was also withdrawn.
The diet drugs and their byproducts have been shown by Roth and others to selectively bind to specific receptors in human heart valve cells, known as 5-HT2B. The same mechanism was seen in the two implicated Parkinson's drugs.
"The two new studies provide the best evidence yet for validating this particular mechanism," Roth tells WebMD. "5-HT2B receptor activity predicts heart valve disease."
Roth, who is a professor of pharmacology at the University of North Carolina School of Medicine, Chapel Hill, says all investigational drugs and byproducts should be screened for 5-HT2B activity in the future.
In an editorial published along with the two studies, Roth called on doctors to avoid prescribing the drugs.