Two drugs used to treat Parkinson's disease have been found to cause damage to heart valves, say researchers.
The drugs, pergolide (Permax) and cabergolide (Dostinex or Cabaser), are in the class of medications called ergot-derived dopamine receptor agonists. Both drugs work to reduce the symptoms of Parkinson's by acting like dopamine, a brain chemical. In Parkinson's disease, too little dopamine is produced by the body, making it difficult for the brain and nervous system to work effectively. This leads to the jerky movements seen in patients with the disease. So, by mimicking dopamine, these drugs allow the patient to better control his movements.
However, new research, published in the New England Journal of Medicine, has found that these drugs may be damaging patients' hearts.
Italian researchers looked at the medical records of 11,417 patients between the ages of 40 and 80 who had received any Parkinson's medication between the 1988 and 2005.
In the sample, 31 patients were diagnosed with cardiac-valve regurgitation, a condition in which the heart valves leak and limit the ability of the heart to work efficiently. Among those with this condition, 12 had been taking either pergolide or cabergolide for up to 12 months previously. Patients on other types of Parkinson's medications did not have any increased risk of developing this condition.
Ultimately, the researchers found that pergolide and cabergolide increase one's risk for a heart valve condition 7 and 5 times, respectively, over patients on a different drug.
Permax already has a black-box warning label about the increased risk of heart-valve problems, based on a small number of patients who were diagnosed with this problem. A milder warning was recently placed on Dostinex. It is not clear if these recent findings will change either label.
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If you are currently taking one of these drugs, be sure to speak to your doctor about your risk of developing a heart-valve defect. He may suggest switching to a different drug or more closely monitoring your condition.
"Our findings suggest that follow-up monitoring is advisible in all patients with Parkinson's disease who are treated with dopamine agonists," wrote Dr. Renzo Zanettini, lead study author.
Pergolide is approved for the treatment of Parkinson's disease in the United States, while cabergolide is only approved for the treatment of a hormonal disorder, hyperprolectinemia, but has been approved in other countries for the treatment of Parkinson's disease and is sometimes prescribed off-label in the United States.
