This study investigates the effects of an investigational medication on individuals with Parkinson's disease. Parkinson's disease is a progressive nervous system disorder that affects movement. The purpose of this study is to assess the safety, tolerability, and how the body processes and responds to the investigational medication when taken orally in multiple doses.

Participants will undergo various study procedures, including holding their Parkinson's disease medications for eight hours before certain assessments. The study will monitor participants' health through physical exams and tests to ensure their safety throughout the trial.

• Who can participate: Participants must have a body mass index between 18 and 35 kg/m2 and a clinical diagnosis of Parkinson's disease meeting UK Brain Bank criteria. They should be able to hold their Parkinson's disease medications for 8 hours before specific assessments.
• Study details: Participants will need to temporarily stop their Parkinson's disease medications for certain assessments. The study will involve monitoring health indicators and conducting physical exams. A placebo is not mentioned in this study.