Treatment of chronic Parkinson's disease with controlled-release carbidopa/levodopa.

Controlled-release carbidopa/levodopa 50/200 (SINEMET CR) and standard carbidopa/levodopa (SINEMET 25/100) were compared in a double-blind, six-month, crossover study involving 21 patients with chronic Parkinson's disease and motor response fluctuations. Daily dosage frequency was significantly reduced with SINEMET CR compared with SINEMET 25/100, while the daily amount of levodopa required with SINEMET CR was significantly greater. No significant differences in disability ratings, motor response fluctuations, or safety were detected during double-blind conditions. In the open-label, dose-finding phase of the study, SINEMET CR was superior to standard SINEMET 25/100 in patient ratings of percent "on" time (good motor function), clinical assessments of motor function, and activities of daily living. This finding resulted from a depreciation of the value of the "old drug" rather than an overestimation of the value of the experimental drug. This double-blind study also suggested that elderly male patients with Parkinson's disease derived the greatest benefit from SINEMET CR.