Safety and effectiveness of istradefylline as add-on therapy to levodopa in patients with Parkinson's disease: Final report of a post-marketing surveillance study in Japan

Abstract

IntroductionIstradefylline is approved in Japan and the US for treatment of Parkinson's disease (PD) in adult patients who experience the wearing-off phenomenon while receiving levodopa; however, safety and efficacy data for real-world clinical use are lacking. MethodsWe report the final results of a prospective, long-term, post-marketing surveillance study of istradefylline adjunct to levodopa for adults with PD experiencing the wearing-off phenomenon. Patients across 214 study sites initiating treatment with oral istradefylline once-daily 20- or 40-mg were followed-up for 1 year. We collected demographic data, disease and treatment histories, and recorded adverse events and adverse drug reactions (ADRs). The priority survey item was the occurrence of psychiatric ADRs. Effectiveness was evaluated by the physician's global and motor function assessments. ResultsCase report forms were collected for 1320 patients, and the safety and effectiveness analysis sets included 1318 and 1284 patients, respectively. The mean age was 71.5 years and 56.2% of patients were women. A total of 274 patients (20.8%) experienced an ADR, 39 patients had a serious ADR, and 7 patients had a fatal ADR that was considered not related to istradefylline. Common ADRs included dyskinesia, hallucination, and visual hallucination. Sixty-five patients (4.9%) experienced a psychiatric ADR. Istradefylline was effective (physician-rated) in 59.8% of patients, and most patients had reduced or unchanged off-time duration, improved or unchanged off-time symptoms, and improved or unchanged motor symptoms. ConclusionIstradefylline safely and effectively improves motor symptoms in PD patients experiencing the wearing-off phenomenon with levodopa therapy in the real-world setting.