Patient description: A 57-year old farmer was diagnosed with Parkinson's disease a year ago. He experiences slowness of movement and tremors. His past medical history is significant for hypertension and hypercholesterolemia. He lives with his wife. They have three children. He used to be active with planting and taking care of their farm animals before his diagnosis. The patient complains of shaking and slow movement. He had difficulty entering through a door, as he was frozen and needed guidance to step in. His handwriting is getting smaller. He is on Levodopa and Trihexyphenidyl. He stated his medications help with shaking and slow movement. But he still has difficulty initiating movements, stiffness and slowness in general. He is an alert and cooperative man who doesn't have any signs of dementia. He doesn't smoke or use any illicit drugs.

Clinical trial eligibility criteria: eligible ages (years): 30.0-999.0,  Parkinson's Disease Main Subjects who are diagnosed with Parkinson's disease as defined by the United Kingdom PD Society Brain Bank for the Diagnosis of PD Modified Hoehn and Yahr Staging ≤ 3 in ON state Mini Mental State Examination Score ≥ 26 Subjects must currently have a good response to levodopa and be receiving a stable dose of levodopa ( at least 4 doses per day of standard levodopa or ≥ 3 doses per day of Rytary™ (Carbidopa and levodopa Extended-Release Capsules) for at least 4 weeks prior to screening) Subjects must experience motor fluctuations with at least 2 hours of OFF periods each day in the awake time Subjects must experience predictable early morning OFF periods Subjects must be able to come to the clinic in the practically defined OFF state Subject must have achieved the following results for home PD diary training, practice diary collection, and Baseline diary recordings (PART B ONLY) During a diary concordance session with an approved PD diary trainer/rater (minimum 4 hours), subject achieved at least 80% overall diary concordance, including at least 1 OFF interval  Diagnosis of secondary or an atypical Parkinsonian syndrome Subject has severe disabling dyskinesia Subject has clinically significant psychosis or hallucinations or history of psychosis in past 6 months History of previous neurosurgery for PD Currently or previously on Duopa/Duodopa Currently on apomorphine or have received apomorphine within 30 days prior to baseline The subject has a diagnosis or history of a substance related disorder (excluding nicotine and caffeine), including alcohol related disorder (Diagnostic and Statistical Manual of Mental Disorders 5 criteria) during the 12 months prior to the Screening Visit The subject has tested positive at the Screening Visit for drugs of abuse (e.g., opiates, cannabinoids, methadone, cocaine, and amphetamines [including ecstasy]) Any medical (including acute or chronic pain), surgical, or psychiatric condition, laboratory value, or concomitant medication which, in the opinion of the Investigator or the reviewer, makes the subject unsuitable for study entry or potentially unable to complete all aspects of the study Suicidal ideation within 1 year prior to the Screening Visit as evidenced by answering "yes" to Questions 4 or 5 on the suicidal ideation portion of the Columbia Suicide Severity Rating Scale (C-SSRS) or attempted suicide within the last 5 years