Parkinson's Disease: Initial Treatment with Levodopa or Dopamine Agonists.

The question of whether to use levodopa (LD) or dopamine agonists as initial therapy in Parkinson's disease has been a controversy for nearly 20 years. There are several issues relating to this treatment regimen that may effect ones decision. Review of them results in the following conclusions: LD does not cause the onset of motor fluctuations and dyskinesia; it probably relates to disease progression. Tolerance does not develop with long-term LD therapy. LD is not toxic. LD decreases mortality in Parkinson's disease. Motor fluctuations can occur with dopamine-agonist monotherapy, but the actual frequency is as yet unknown. Dopamine agonists are not neuroprotective. Clinical trials have indicated that LD remains the most potent symptomatic therapeutic agent available. Dopamine agonists do provide some symptomatic relief when used alone in early Parkinson's disease. Standard preparations of LD have the same effect on early disease as controlled release preparations. Dopamine agonists cause less dyskinesia and fluctuations. These conclusions indicate that both drugs are effective symptomatic agents with their own positive and negative aspects. There is no incorrect choice. It is reasonable to start young onset patients (younger than 50 years of age) with an agonist, because they seem to be more prone to develop motor fluctuations and dyskinesia. However, if employment is in jeopardy then LD may be needed. Because agonists cause more hallucinations, freezing, and somnolence, problems of particular relevance to the elderly (older than 70 years), then LD would be the best agent for older onset patients. In general, but particularly for those falling in between these age groups, treatment should be individualized. In this time of cost effectiveness, LD remains the least expensive of these agents.