A Study to Evaluate the Efficacy of 18 to 24mg/Day Ropinirole Controlled Release (CR) Tablets in Early and Advanced Parkinson's Disease (PD) Patients.

This study is a Phase III, multicentre, randomized, initial double-blind study with subsequent open label phases. The study will havea screening phase (4 weeks), a dose increase effect verification phase (12 weeks), a down titration 1 phase (1 week), a long-term phase (39 weeks), down titration 2 phase (1 to 2 weeks) and a follow up phase. Subjects will be assigned to Ropinirole CR high-dose group or Ropinirole CR maintenance group at a ratio of 3:1. This study is being conducted to evaluate the efficacy (effect of increasing Ropinirole dose from 16 mg/day to 18-24 mg/day) of the Ropinirole CR tablets in early and advanced PD patients who have not achieved an optimal therapeutic response with marketed Ropinirole Immediate release (IR) (15 mg/day) or marketed Ropinirole CR (16 mg/day) formulations.