Clinical study compares treatments in early Parkinson's disease

University of Tennessee Health Science Center professor and vice chair of the Department of Neurology, Ronald F. Pfeiffer, M.D., has been an investigator with The Parkinson Study Group (PSG), which recently reported four-year results of a major long-term, multi-center clinical trial.

During the trial, researchers studied pramipexole versus levodopa for initial treatment in Parkinson's disease (PD), and results are published in the July issue of the Archives of Neurology. These results confirm and extend the two-year observations previously published in JAMA (20000, 284:1931-1938).

Patients with early Parkinson's who were treated initially with pramipexole resulted in a reduction of dyskinesias and wearing off compared with initial treatment with levodopa. Initial treatment with levodopa resulted in a lower incidence of freezing,

somnolence, and edema, and better motor performance, as measured by the Unified Parkinson's Disease Rating Scale (UPDRS).

Pramipexole, a dopamine agonist or a drug used to treat the signs and symptoms of Parkinson's and levodopa, the drug most commonly used to treat early PD symptoms, were compared as initial treatments for those with early PD. Research physicians at 22 Parkinson Study Group sites in the United States and Canada evaluated 301 participants in this four-year study.

The primary outcome of the study was the amount of time to the first occurrence of dopaminergic motor complications, problems resulting from taking medication, such as the drug wearing off, dyskinesia - abnormal, involuntary movements, and on-off fluctuations.

After four years, results showed about half (52%) of subjects assigned to initial pramipexole treatment reached the primary endpoint as compared with almost three quarters (72%) of the levodopa-initiated subjects. However, the average improvement in total UPDRS scores, measured at the first study visit and again at the last study visit, was greater in the levodopa group than in the pramipexole group. The UPDRS or Unified

Parkinson's Disease Rating Scale, is a standardized measure of patient's abilities to perform basic motor skills, as well as the effect of the disease on activities of daily living and mental abilities. The most commonly observed side effects of pramipexole were somnolence and edema. The most commonly observed side effects of levodopa were dyskinesias and wearing off.

"Levodopa and pramipexole both appear to be reasonable options as initial dopaminergic therapy for PD, but are associated with different profiles of efficacy and adverse effects," said Ira Shoulson, MD, professor of neurology, University of Rochester and principal investigator of the study. "However, further study is needed to assess the longer-term outcomes and cost-effectiveness of these treatments."

The PSG (www.Parkinson-Study-Group.org) is a non-profit, cooperative group

of Parkinson's disease experts from medical centers in the United States and Canada who are dedicated to improving treatment for persons affected by Parkinson's disease.

Parkinson's Disease is a neurological illness that affects approximately 1.5 million Americans and is caused by the graduate loss of cells in a small part of the brain. The loss (death) of these cells produces a reduction in a vital chemical called "dopamine," which causes symptoms that may include shaking of hands, slowing down of movement, stiffness and loss of balance. Because PD is a progressive disorder, these symptoms worsen with time.

The study was supported by Boehringer/Ingelheim Pharmaceuticals, Inc. and Pfizer, Inc. who co-promote MIRAPEX (pramipexole) in the United States for Parkinson's disease.