Long-Term Effects of Early Parkinson's Treatments Similar

A study published online today 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.

The initial study followed 301 Parkinson’s patients in 22 sites in the U.S. 
and Canada over a 2 year period.A sub-set (222) of the group was followed for 
an additional 4 years. Half the patients were randomly assigned to be 
initially treated with levodopa and the other half with pramipexole.After 6 
years of follow-up, essentially all of the participants (90%) were taking 
levodopa.The researchers evaluated study participants using tools that measure 
disability (ability to perform daily activities), side effects, disease 
severity, and the patient’s sleepiness.

The study confirmed that patients who are initially treated with levodopa are 
more likely to develop motor complications such as dyskinesias and wearing off 
even 6 years after treatment.However, it also shows that these complications 
did not have a significant impact on the quality of life or disability of the 
patients.

“Clinicians and patients still need to establish their treatment priorities to 
understand unique circumstances that argue in favor of one drug vs. the 
other,” said Biglan. “However, this study should assuage any concerns that the 
treatment decisions that are made early in the disease will have long-term 
implications, which does not appear to be the case.”

The study was conducted by the Parkinson’s Study Group CALM (Comparison of the 
Agonist Pramipexole with Levodopa on Motor Complications) Cohort and funded by 
Pharmacia Corp. and Boehringer Ingelheim.

For more media inquiries, contact:
Mark Michaud
(585) 273-4790
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