Long-acting carbidopa-levodopa in the management of moderate and advanced Parkinson's disease.

Parkinson's disease patients treated chronically with levodopa often develop fluctuations in motor response. Motor fluctuations can be attributed in part to oscillating plasma levodopa concentrations. A controlled-release formulation containing 200 mg of levodopa and 50 mg of carbidopa provides superior plasma levodopa profiles compared with the standard preparation. A multicenter, double-blind trial involving 202 patients with fluctuating motor response found controlled-release carbidopa-levodopa to be safe and tolerable, with improved efficacy compared with the standard formulation. Long-term exposure to the controlled-release formulation, at least for a period of 3 years, does not appear to be associated with any increase in the incidence of adverse side effects.