A study published online in the Archives of Neurology involving two common drugs used to treat early-stage Parkinson's disease shows that, while the drugs each have advantages and disadvantages, the overall impact tends to even out over a long period of treatment.
"Clinicians and patients often struggle with what is the right initial approach to treating Parkinson's disease," said University of Rochester Medical Center neurologist Kevin Biglan, M.D., M.P.H., the lead author of the paper and a member of the Parkinson's Study Group, an international network of researchers that oversaw the clinical trial. "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."
Parkinson's disease is a progressive neurological disorder that erodes a person's control over their movements and speech. Over time, Parkinson's patients may experience stiffness or rigidity of the arms and legs, slowness or lack of movement, and walking difficulties, in addition to tremors in their hands, arms, legs, jaw or face.
The study compared two drugs - levodopa and pramipexole - that are generally employed as the first line of treatment for Parkinson's disease. The two drugs use different mechanisms to counteract the decline in the production of dopamine in the brain that is a result of a progressive loss of cells that secrete the neurochemical. Levodopa is an amino acid that the body metabolizes into dopamine. Pramipexole is a dopamine agonist that binds with dopamine receptors on cells in the brain and mimics the chemical's molecular function.
While levodopa is considered to be better at addressing the motor control symptoms of the disease such as mobility issues and tremors, it is also associated with side effects such as dyskinesia (involuntary movements) and the effectiveness of the drug can diminish, or wear off, over time. Pramipexole is less effective with respect to motor control symptoms and more often causes sleepiness, but is less commonly associated with dyskinesias and wearing off. Pramipexole is often prescribed because clinicians believe it essentially extends the window in which the patient can benefit from levodopa by delaying the initial use of the drug -and its eventually wearing off. Most Parkinson's patients end up taking levodopa at some point regardless of their initial treatment because it is more effective at improving the symptoms of the disease.