IntroductionA dopamine agonist patch could be an important treatment option for Parkinson's disease. This study evaluated the long-term efficacy and safety of the ropinirole hydrochloride patch. The steady state plasma ropinirole concentration was also assessed. MethodsIn a multicenter, open-label, uncontrolled study, Parkinson's disease patients with/without basal levodopa and with/without prior dopamine agonist therapy (any of these four regimens) received application of a ropinirole patch once daily for up to 52 weeks with unforced titration from 8 to 64 mg. For patients with prior dopamine agonist therapy, the initial dose of ropinirole patch was determined from the prior dopamine agonist dose by using a conversion table. ResultsMost adverse events were mild or moderate. All application site adverse events were mild, except for moderate application site erythema in one patient. In patients with prior dopamine agonist therapy, switching to ropinirole patch did not lead to a significant early increase of adverse events. A change from baseline in the UPDRS Part III total score, the primary efficacy endpoint, showed improvement until Week 16 compared with baseline, followed by little subsequent change until Week 52, indicating maintenance of efficacy. The plasma ropinirole concentration was at steady state throughout the study period and showed a dose-proportional increase. ConclusionOnce-daily application of ropinirole patch showed long-term efficacy and safety (52 weeks) for Parkinson's disease. Switching from other dopamine agonists to ropinirole patch was effective and safe. The plasma ropinirole concentration was at steady state throughout the study period and showed a dose-proportional increase.