This study is exploring the safety of a drug called buntanetap for people with Parkinson's Disease (PD). Parkinson's Disease is a disorder that affects movement. The study will last for 36 months (3 years) and will be "open-label," meaning everyone will know they are receiving buntanetap. There are two groups in this study: one group includes people who have been in a previous buntanetap study, and the other includes those receiving deep brain stimulation (DBS) treatment, which is a surgery that helps control symptoms of Parkinson's. Participants will take 30mg of buntanetap once a day after a screening process that can last up to 42 days. Screening is a check to see if someone is suitable for the study.

• Participants will have to stop certain Parkinson's medications before study visits.
• The study lasts for 3 years, with required visits to the clinic.
• People in the study must have a support person with them at visits.