A Study to Evaluate the Effectiveness of Two Doses of AP-472 as Adjunctive Therapy to Levodopa in Parkinson's Disease (PD) Participants With Motor Fluctuations

This is a Phase 2 study in people with Parkinson's disease who experience motor fluctuations while taking levodopa. The study will evaluate how effective two different doses of the study drug AP-472 are when added to levodopa treatment, compared with a placebo. The study will last about 12 weeks. Participants will be randomly assigned to receive one of the two doses of AP-472 or a placebo. Neither the participants nor the study staff will know which treatment is given. The study includes a screening period, a 4-week period during which Parkinson's medications must remain stable, and an 8-week treatment period. During the treatment period, limited adjustments to levodopa are allowed if needed.