A Study to Evaluate the Efficacy, Safety and Tolerability of SEP-363856 in Subjects With Parkinson's Disease Psychosis

This is a multicenter, randomized, parallel-group, placebo-controlled study evaluating the efficacy, safety, and tolerability of double-blind SEP-363856 flexibly dosed at 25, 50, or 75 mg/day for 6 weeks followed by 12 weeks of open-label extension of SEP-363856 flexibly-dosed at 25, 50, or 75 mg/day in male and female subjects ≥ 55 years of age with a clinical diagnosis of PDP. The study will randomize approximately 36 subjects to 2 treatment groups in a 2:1 ratio (approximately 24 subjects to SEP-363856 and 12 to placebo). The study will consist of 4 periods: Screening/Washout Period (up to 14 days prior to Double-blind Treatment), Double-blind Treatment Period (6 weeks), Open-label SEP-363856 Treatment Period (12 weeks), and Follow-up Period (1 week after last dose) as shown in the following figure. All postBaseline clinic visits will have a window of ± 2 days relative to the date of the Baseline visit (Visit 3).