This study tests a new drug, Lenrispodun, for people with Parkinson's Disease (PD) who have movement issues like "wearing off" and "dyskinesia" (uncontrolled movements caused by medication). It's a multicenter (conducted at several locations), randomized (participants are chosen by chance), double-blind (neither participants nor researchers know who gets the real drug), and placebo-controlled (some get a fake treatment) study. Participants are randomly given Lenrispodun or a placebo for 4 weeks. The study includes three parts: screening (up to 4 weeks to check if you qualify), treatment (4 weeks on the drug or placebo), and follow-up (1 week to check safety).

• Duration: Up to 9 weeks total, including follow-ups.
• Visits: Multiple visits for checks and safety monitoring.
• Eligibility: Must be 40+, have PD, and stable on current PD meds.

People with other types of parkinsonism, late-stage PD, or certain medication uses can't join. Participants need a caregiver to help if needed.