Initial Treatment for Parkinson's: L-Dopa or Dopamine Agonist?

In patients with Parkinson's disease, first-time therapy with L-dopa (eg, Sinemet) provides modestly better motor function and health-related quality of life in the long term than the dopamine agonist bromocriptine (Parlodel). The final, 14-year results of the open, randomized, multicenter study of 3 initial treatments from the PD Research Group of the United Kingdom (PDRG-UK) were published yesterday in the online edition of Neurology.

Previous, interim results from the trial had shown a significantly higher mortality rate with initial L-dopa plus the MAO-B inhibitor selegiline (Eldepryl), leading to discontinuation of that treatment arm in 1995. Ten-year results showed no significant difference in mortality between L-dopa and bromocriptine; although patients who initially received bromocriptine demonstrated slightly worse disability scores but a lower rate of dyskinesias.

In the latest report, data from 166 surviving participants of the original 782 enrollees were assessed. Disability scores and physical functioning were statistically significantly better in patients who initially received L-dopa; however, there were no treatment differences in mortality, dyskinesias, motor fluctuations, or cognitive function.

On the basis of the cumulative data, the authors recommend dopamine agonists as initial treatment for mild PD, particularly in younger patients and when motor function is the chief concern. However, they conclude that initial L-dopa "remains the most efficacious therapy for motor improvement" and should be considered early for all PD patients.

MAO-B = monoamine oxidase B.

Image of 1886 drawing of PD patient by neurologist Sir William Richard Gowers at Wikimedia Commons.