A Study of Buntanetap in Participants With PD

This study will examine the long-term safety of buntanetap in participants with PD. This will be a 36-month open-label safety study. This study will be conducted with two cohorts. Cohort 1 will enroll via invitation only for PD participants who have previously participated in buntanetap clinical trials. Cohort 2 will be for PD participants who are receiving deep brain stimulation (DBS) treatment. Qualified participants will receive buntanetap 30mg QD after a screening period of up to 42 days. MMSE, MoCA, C-SSRS, and MDS-UPDRS will be assessed by clinicians who have successfully completed the requisite certifications/trainings for each assessment. Each participant shall be assessed by the same clinician throughout the study. Cohort 1 participants will stop standard of care Parkinson's medications 12h before baseline and annual clinical visits to ensure clinical OFF-state during visit. Cohort 2 participants will stop standard of care Parkinson's medications 12h before all clinic visits. The night before the baseline and annual clinic visits (or early termination visit), Cohort 2 participants will return DBS settings to their initial baseline settings.