• Male or female subjects ≥ 18 and ≤ 85 years of age, at time of informed consent.

• Diagnosed with symptomatic orthostatic hypotension due to Parkinson's disease or pure autonomic failure (i.e. neurogenic orthostatic hypotension).

• At Screening, subjects must meet the diagnostic criteria of neurogenic orthostatic hypotension, as demonstrated by a decrease ≥20 mm Hg in systolic or ≥10 mm Hg in diastolic BP upon standing ≤3 minutes from a supine position.

• At Screening, subjects must have a score ≥4 on the Orthostatic Hypotension Symptom Assessment (OHSA) scale question #1.

• Currently receiving, or known to be responsive to, direct or indirect α1-AR agonists (e.g., midodrine, droxidopa) for treatment of nOH.

• If the Investigator determines that additional autonomic function testing is required to confirm the diagnosis of autonomic dysfunction, the Valsalva maneuver may be performed to show the absence of BP overshoot during phase IV.

• Body weight greater or equal to 50 kg and body mass index (BMI) between 18 and 35 kg/m2, inclusive at Screening.

• Stable medical conditions for 3 months prior to Screening.

• For patients taking antiparkinsonian medication: stable dose of levodopa, dopamine agonist, amantadine, and/or monoamine oxidase B inhibitor, i.e. unchanged for 1 month.

⁃ Subject is ambulatory with/without the use of an assistive device.

⁃ Willing to follow the protocol requirements and comply with protocol restrictions.

⁃ Capable of providing informed consent and complying with study procedures.

⁃ Able to speak, understand, and read English.