This study is testing a new medicine called VG081821AC, which is a tablet that people with early or mid-stage Parkinson's disease take by mouth. Parkinson's disease is a brain disorder that affects movement, making it hard to control how your body moves. VG081821AC works by blocking a special protein in the brain, which might help people move better. Currently, many people with Parkinson's use a medicine called levodopa, but it can cause side effects. This study will check if VG081821AC can help improve movement without these side effects. A total of 152 adults in China will be part of this study.

• Study Length: 12 weeks, with 8 visits to the study center.
• Groups: Participants will be divided randomly into four groups, with some receiving VG081821AC and some getting a placebo (a fake pill).
• Eligibility: Must be 18-80 years old, diagnosed with Parkinson's, and meet other health criteria.