Norepinephrine-targeted Therapy for Action Control in Parkinson Disease

Inclusion Criteria

• Nondemented man or woman 18 years of age or older with idiopathic PD based on the UK Parkinson Disease Society Brain Bank Clinical Diagnostic Criteria (refer to Appendix C for the criteria)
• Unified Parkinson Disease Rating Scale (UPDRS) motor scores OFF medication consistent with postural instability gait difficulty (PIGD) subtype
• Symptoms of freezing or falls
• Able to walk at least 10 meters
• Medically stable outpatient, based on the investigator's judgment
• The patient must be willing and able to give written informed consent prior to performing any study procedures.

Exclusion Criteria

• Score of 21 or lower on Montreal Cognitive Assessment
• Sustained supine hypertension greater than or equal to 180 mmHg systolic or 110 mmHg diastolic, or have these measurements at their Baseline Visit (Visit 2). Sustained is defined as measurements persistently greater at 2 separate measurements at least 10 minutes apart with the subject supine and at rest for at least 5 minutes.
• Concomitant use of vasoconstricting agents such as ephedrine, dihydroergotamine, or midodrine. Concomitant use of other noradrenergic medications, such as serotonin-norepinephrine reuptake inhibitors (SNRI's) is also contraindicated. Patients must stop taking these drugs at least 2 days or 5 half-lives (whichever is longer) prior to their baseline visit and throughout the duration of the study.
• Diagnosis of hypertension that requires treatment with antihypertensive medications (short-acting antihypertensives to treat nocturnal supine hypertension are allowed in this study)
• Women of childbearing potential
• Any significant uncontrolled cardiac arrhythmia
• History of myocardial infarction, within the past 2 years
• Current unstable angina
• Congestive heart failure (NYHA Class 3 or 4)
• History of cancer within the past 2 years other than a successfully treated, non-metastatic cutaneous squamous cell or basal cell carcinoma or cervical cancer in situ
• History of stroke
• Gastrointestinal condition that may affect the absorption of study drug (e.g., ulcerative colitis, gastric bypass)
• Musculoskeletal disorders such as severe arthritis, post knee surgery, hip surgery, or any other condition that the investigators determine may impair assessment of gait
• History of myocardial infarction, uncontrolled cardiac arrhythmia, unstable angina, congestive heart failure, or stroke
• Untreated closed angle glaucoma
• Musculoskeletal or other disorders that may impair assessment of gait
• Any major surgical procedure within 30 days prior to the Baseline visit
• Previously treated with droxidopa within 30 days prior to the Baseline visit
• Currently receiving any other investigational drug or have received an investigational drug within 60 days prior to the Baseline visit
• Known or suspected alcohol or substance abuse within the past 12 months (DSM-IV definition of alcohol or substance abuse)
• Any condition or laboratory test result, which in the Investigator's judgment, might result in an increased risk to the patient, or would affect their participation in the study.