An open-label conversion study of pramipexole to ropinirole prolonged release in Parkinson's disease.

Ropinirole prolonged release (PR) is a once daily oral dopamine agonist approved for the treatment of Parkinson's disease (PD). The goal of this 4 week, open-label study was to determine the most effective conversion ratio with the fewest adverse effects (AEs) when switching from pramipexole to ropinirole PR. Sixty patients with PD taking pramipexole were converted overnight to ropinirole PR at ratios of 1:3, 1:4, or 1:5 such that 20 consecutive subjects were enrolled in each group. Ropinirole PR dose adjustments were allowed to maintain efficacy or to reduce AEs. An overnight switch from pramipexole to ropinirole PR was found to be well tolerated and AEs were typical for a dopamine agonist. The most common AEs were worsening of PD symptoms, dizziness, somnolence, and nausea, the majority of which resolved after dose adjustments. Thirteen subjects discontinued ropinirole PR before 4 weeks. These subjects were taking a significantly greater dose of pramipexole, the majority greater than 4 mg/day, and tended to have longer disease durations. A conversion ratio of 1 mg of pramipexole to 4 mg of ropinirole PR resulted in the fewest discontinuations of ropinirole PR, the fewest dose adjustments and the largest percentage of subjects that preferred ropinirole PR.