Long-term efficacy of controlled-release carbidopa/levodopa in patients with advanced Parkinson's disease

Twenty-one patients with Parkinson's disease and motor fluctuations who completed a double-blind study comparing controlled-release carbidopa/levodopa (Sinemet CR4) with standard Sinemet (SS) were evaluated one year following completion of the study. Five patients remained on CR4 alone; 16 continued on CR4 plus SS, and one also required addition of bromocriptine. Patients were significantly worse (p < 0.05) at one year compared with double-blind CR4 phase (DBCR) for nine parameters of the motor exam, six activities of daily living (ADL), Hoehn and Yahr staging, and physician's global assessment. Compared with baseline SS, patients were worse at one year for four points of the motor exam, two of mentation, behavior, and mood, and 11 parameters of ADL. Improvement at one year was noted for less action and postural tremor and decreased duration of dyskinesias for both comparison periods. There was elimination of early monitoring dystonia at one year over the DBCR period and more hours 'on' without dyskinesias and fewer hours 'on' with dyskinesias compared with baseline SS. Total levodopa dosage was not significantly changed over the year. These data suggest that, in long-term use, CR4 remains more efficacious than SS alone for Parkinson's patients experiencing motor fluctuations, although disease progression continues despite optimal medication.