[Are dopamine agonists alternative therapy for levodopa in early stage of Parkinson's disease? Yes]

Abstract

Dopamine agonists (DA) are a class of drugs which is currently developing and expanding. They started to be used as a supplement to levodopa therapy for reducing fluctuations and dyskinesia in the 80's and 90's. In the past 10 years dopamine agonists have more often been considered as an initiating therapy in PD. Dopamine agonist therapy was chosen ahead of levodopa because it reduced the risk of motor complication development and probable neuroprotective effect. Dopamine agonists offers other advantages over levodopa: they act directly on dopamine receptors, and therefore metabolic conversion is not required for the effect to be exerted; the circulating plasma amino acids do not compete with DA for absorption and transport into the brain; DA have a longer half-life than levodopa and they do not undergo oxidative metabolism and do not generate free radicals or induce oxidative stress. The efficiency and safety of DA therapy in the early stage of PD has been proven in many evidence-based medicine trials. The antiparkinsonian effect of DA was superior to the placebo and comparable to levodopa in early-stage PD. The most important advantage of DA is proven reduced occurrence of motor complications in comparison with levodopa.