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.