Current status of levodopa therapy in idiopathic Parkinson's disease.

Levodopa is currently used at all stages of Parkinson's disease, particularly from Stage 3 onward. Most patients start levodopa within four years of the onset of disease, earlier in the akineto-rigid patients (average delay of 2.1 years) than in those where resting tremor predominates (average delay of 3.4 years). Advanced age (greater than 80) is no deterrent to the use of levodopa if required. Wearing off is most noticeable in Stage 3 or after 10 years of therapy with levodopa. An inverse correlation was found between age and wearing off, suggesting a marked sensitivity of younger patients to levodopa. Future studies on the use of dopamine agonists should thus be stratified according to age.