Initial therapy for Parkinson's disease: levodopa vs. dopamine receptor agonists.

Levodopa therapy is essential for patients in the advanced stages of Parkinson's disease. However, at early stages, DA agonist therapy has similar efficacy in the treatment of parkinsonism and a lower incidence of motor complications compared to levodopa therapy several years after the initiation of the therapy. The main factors causing motor complications have been speculated to be a severe reduction of dopaminergic nerve terminals because of disease progression, and a pulsatile stimulation of DA receptors using a drug with a short plasma half-life. DA agonists have longer plasma half-lifes than levodopa; therefore, they are expected to have a favorable effect on motor complications. Moreover, two clinical reports confirmed the potential neuroprotection by DA agonists. Although the patient's conditions should be considered in the selsction of a drug, DA agonist therapy is recommended as the initial therapy for Parkinson's disease.