DOCTORS TREATING patients with Parkinson’s disease have been advised to exercise caution when prescribing a drug licensed to treat the progressive neurological disorder.
The maximum dose of the drug pergolide has been reduced from 5mg per day to 3mg per day after the drug was found to cause heart problems in people who had been taking it for a long period of time or at a higher dose.
Drug regulators in Europe and the Republic have now changed the prescribing instructions for pergolide, so that patients must now undergo a full cardiac evaluation before the drug is prescribed. The new stipulation was made after pergolide was linked to valve problems in the heart, the result of thickening of the valve due to a process called fibrosis.
Pergolide, which is used as a second line agent in the treatment of Parkinson’s, is not related to dopamine (levodopa), the principal drug used to treat the disease.
But it now appears that pergolide can cause the heart valves, which control blood flow through the heart, to malfunction. The drug has also been linked with fibrosis in the lung.
Doctors have been asked to look out for symptoms such as shortness of breath, persistent cough or chest pain in patients taking pergolide.
Heart failure may also occur and patients must undergo a cardiac ultrasound (echocardiogram) at regular intervals. An echocardiogram is the investigation of choice when assessing the function of the heart’s valves.
According to the amended summary of product characteristics (SPC) for pergolide, “in some cases symptoms or malfunctions of cardiac valvulopathy improved after discontinuation of pergolide”.
However, the SPC also notes that valve problems and fibrosis have been found when pergolide is used at doses less than 0.5mg per day.
Parkinson’s disease is a chronic neurological illness precipitated by the deficiency of a chemical messenger in the brain called dopamine. Parkinson’s is essentially a disorder of movement, although other functions are also affected.
Dopamine is the main lubricant for the brain’s gearbox. As this part of the brain seizes up, the three main symptoms of tremor, muscular rigidity and bradykinesia (slowness in initiating movement with associated freezing) appear.