Comparison of ropinirole controlled- and immediate-release in Japanese patients with advanced Parkinson's disease

Background: In Japan, ropinirole controlled-release tabletsrecently became available for Parkinson's disease. Aim: We compared the efficacy and safety of ropinirole controlled-release with ropinirole immediate-release. Methods: We carried out a phase III clinical trial (randomized, double-blind, double-dummy), in which controlled-release (n = 156) or immediate-release (n = 146) was given to Japanese patients with advanced Parkinson's disease under L-dopa treatment. First, we assessed the non-inferiority of ropinirole controlled-release to immediate-release at week 24 by measuring change from week 0 in total score of the Unified Parkinson's Disease Rating Scale Part III. Then, during weeks 26-32, we evaluated the safety and efficacy of patients' switching from ropinirole immediate-release to controlled-release, and a subset of patients continued on ropinirole controlled-release though week 54. Results: The change in the Unified Parkinson's Disease Rating Scale Part III total score at week 24 was -10.8 for the controlled-release group and -11.1 for the immediate-release group (adjusted mean difference: 0.34, two-sided 95% confidence interval -1.41 to 2.09), and the upper limit of the confidence interval was less than the predefined margin of 2.5, showing the non-inferiority of ropinirole controlled-release to immediate-release. The efficacy did not change after overnight switching from ropinirole immediate-release to controlled-release, and lasted until week 54. Adverse events were comparable between the two groups during the whole study period. Conclusions: As adjunctive therapy to L-dopa, ropinirole controlled-release improved motor symptoms in Japanese patients with advanced Parkinson's disease. The overnight switch from immediate-release to controlled-release did not result in any unexpected adverse event.