A Fixed Dose, Dose-response Study of Ropinirole Prolonged Release (PR) as Adjunctive Treatment to L-dopa in Patients With Advanced Parkinson's Disease

This is a double blind, fixed dose, parallel group study to characterize the dose response of ropinirole PR as adjunctive therapy to L-dopa in patients with late stage Parkinson's disease. The primary endpoint of this study, mean change from baseline in total awake time spent "off' is the same endpoint as used in the ropinirole PR pivotal study for advanced Parkinson's disease patients. This study includes a wide range of ropinirole doses (4-24mg) with the 8mg, 12mg, and 16mg per day doses powered to detect a 1.7 hour difference in total awake time spent "off" compared with placebo. The dose of Ldopa will remain stable through the study, unless the subject experiences tolerability issues that require an L-dopa dose reduction. Up to three L-dopa dose reductions are allowed, making a total reduction of up to approximately 30%. Keeping the L-dopa dose constant where possible is important to avoid confounding the efficacy data. Clinical review of the primary and secondary endpoints will be performed in order to establish the lowest maximally effective therapeutic dose.