Parkinson's Treatment Drugs Even Out Over Long Term
WEDNESDAY March 11, 2009 -- Two drugs -- levodopa and pramipexole -- used to treat early stage Parkinson's disease each have advantages and disadvantages, but their overall impact appears to even out over a long period of treatment.
That's the conclusion of a new study that included hundreds of patients in Canada and the United States.
"Clinicians and patients often struggle with what is the right initial approach to treating Parkinson's disease. This study tells us that, over the long haul, patients on the different drugs end up at roughly the same place in terms of their level of disability and quality of life," lead author Dr. Kevin Biglan, a neurologist at the University of Rochester Medical Center in New York, said in a school news release.
The two drugs use different mechanisms to counteract the decline in the production of dopamine in the brain that causes Parkinson's symptoms. Levodopa is an amino acid that the body metabolizes into dopamine. Pramipexole binds with dopamine receptors on cells in the brain and mimics dopamine's molecular function.
Levodopa is considered better at treating motor control problems in Parkinson's patients but is also associated with side effects such as dyskinesia (involuntary movements), and the effectiveness of the drug can wear off over time. Pramipexole is less commonly associated with dyskinesea and wearing off, but is less effective in treating motor control problems and more often causes sleepiness, according to background information in the news release.
Doctors often prescribe pramipexole first, because it extends the length of time a patient can benefit from levodopa before its effect wears off.
The initial study included 301 patients at 22 sites who were followed for two years. A subset of 222 of those patients was followed for an additional four years. At the start of the study, half the patients were randomly selected to receive levodopa and half to receive pramipexole. After six years of follow-up, 90 percent of patients were taking levodopa.
Patients initially treated with levodopa were more likely to develop motor control complications such as dyskinesia and wearing off, but these complications didn't have a significant impact on patients' quality of life or disability, the researchers found.
The study, published online March 9 in the journal Archives of Neurology, was funded by Pharmacia Corp. and Boehringer Ingelheim.
Posted: March 2009