The U.S. Food and Drug Administration (FDA) issued a drug safety alert to neurologists and patients about an increased risk of congestive heart failure (CHF) with pramipexole (MIRAPEX), a drug approved for the treatment of both Parkinson’s disease and restless leg syndrome.
“Results of recent studies suggest a potential risk of heart failure that needs further review of available data…”
The FDA’s alert follows the review of data from all randomized, controlled trial studies of pramipexole submitted to the agency by the drug’s manufacturer, Boehringer Ingelheim, and the results of two recent epidemiology studies assessing the risk of heart failure in patients taking Parkinson’s disease drugs. The FDA is currently working with Boehringer Ingelheim to determine the risk of Mirapex associated heart failure. Even though the FDA felt the data was inconclusive due to limitations in the study, it is advised that patients who take this drug be alert for symptoms of CHF.
Parkinson’s disease is a progressive, degenerative disorder of the brain primarily affecting motor or muscle function. It was first recognized almost two hundred years ago. Parkinson’s disease most often strikes people over the age of 50, with an average age of 70 at the time of diagnosis, and is caused by the destruction of the brain cells that product dopamine, a chemical involved in the control of movement.
The most common symptoms of Parkinson’s disease are tremors (rhythmic shaking), slowness of movements, difficulty walking, impaired coordination and stiff muscles. Patients often develop loss of balance, resulting in frequent falls, dementia, hallucinations, depression, sleep disturbances and difficulty swallowing as the disease progresses.
Unfortunately, there is no cure available for Parkinson’s disease. The currently available drugs for treating Parkinson’s disease only target the symptoms and do not slow or reverse the underlying destruction of the dopamine-producing brain cells.
The cause of primary restless leg syndrome is unknown and is defined by subjective symptoms. The disorder has been heavily marketed by pharmaceutical industry-focused disease-awareness campaigns, which have portrayed this condition as a serious illness.
The four criteria that make up restless leg syndrome are: an urge to move the legs, the onset, or worsening of symptoms when at rest, relief by movement, and symptoms that can occur primarily at rest and interfere with sleep or rest. Mild symptoms of restless leg syndrome have been reported in 5-15 percent of the U.S. population.
After gathering and examining data from randomized trials, the FDA found more cases of heart failure (12 of 4,157) among patients treated with pramipexole than among those on placebo (4 of 2,820). The agency stressed that the difference was “not statistically significant.”
Mirapex was approved in 1997 and is a member of a class of medicines called dopamine agonists. It is also used off-label for treating cluster headaches and sexual dysfunction. Miraplex is also being investigated for the treatment of depression and fibromyalgia.
In two studies using data from Europe, the increased risk of Mirapex heart failure was statistically significant. In one of the studies, a case control study using a database of patients aged 40-89 years treated with anti-parkinson drugs, the risk of heart failure associated with any use of dopamine agonist compared with no use was increased by almost 60 percent (relative risk 1.58). The Mirapex heart failure relative risk was 1.86 and 2.07 with another dopamine agonist cabergoline. Both of these risks were higher with no use of these drugs.
Because of limitations in the studies, it is very hard to decide whether higher heart failure rates was linked to Mirapex therapy or to some other influencing factor(s).
Doctors are asked to carry on following the recommendations in the drug label when prescribing pramipexole. All patients on pramipexole should continue taking it according to their doctors’ instructions, the FDA urged. If you have any doubts concerning pramipexole, ask your health care professional.
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