As a treatment strategy for early Parkinson’s disease, initial therapy with levodopa versus pramipexole appears to be comparable in delaying the progression of this neurological disease.

However, each treatment has a different side-effect profile, which may determine which is the best drug for each patient, researchers report in the Archives of Neurology. Levodopa is more likely to cause dopaminergic events, whereas pramipexole is more likely to cause sleepiness and swelling from water retention.

Dopaminergic events can arise from imbalances of dopamine, a neurotransmitter in the brain that involves involuntary muscle control and movement, attention, learning, and the brain’s pleasure and reward system.

The findings come from an extended follow-up study of 301 patients who participated in an earlier Parkinson’s disease trial. As part of the study, clinicians were permitted to add levodopa or other antiparkinsonian drugs as needed for ongoing or emerging disability.

At 6 years’ average follow-up, the scores on a scale of activities of daily living and another scale were comparable in all of the patients initially treated with levodopa versus pramipexole.

Roughly 68 percent of initial levodopa patients experienced dopaminergic motor complications compared with 50.0 percent of initial pramipexole patients. Still, disabling dyskinesias - involuntary muscle movements - were uncommon with both treatment approaches.

The results suggest that the side effect profiles of the initial levodopa and pramipexole strategies and not their efficacy on long-term disability should guide treatment decisions, the investigators conclude.

SOURCE: Archives of Neurology, March 9, 2009.