A Phase IV Study in Subjects With Neurogenic Orthostatic Hypotension

Inclusion Criteria: * The male or female subjects must be 18 years of age or older and ambulatory. (Subjects must not require assistance with a walker or wheelchair to perform regular daily activities at all times.) * Women of childbearing potential must have a negative serum beta HCG pregnancy test at screening and baseline. * The subject has been diagnosed with symptomatic orthostatic hypotension due to Parkinson's disease, multiple system atrophy, pure autonomic failure or autonomic neuropathy (i.e. neurogenic orthostatic hypotension). * The subject manifests one of the following symptoms while standing or has a history of one of the following when not treated for orthostatic hypotension: dizziness, lightheadedness, feeling faint or feeling like they may black out. * The subject is willing and able to undergo the procedures required by this protocol including morning office visits, assessment completion, protocol compliance and participation in the wash-out period. * The subject has signed an Institutional-Review-Board approved written informed consent form prior to any study procedures taking place. Exclusion Criteria: * The subject is a pregnant or lactating female. * The subject has pre-existing sustained supine hypertension greater than 180 mm Hg systolic and 110 mm Hg diastolic. * The subject is taking medications such as vasodilators, pressors, diuretics, ACE inhibitors, angiotensin receptor blockers, beta-blockers, combined alpha and beta-blockers, MAOI's, herbals or specific mixed effect medications. * The Principal Investigator deems any laboratory test abnormality clinical significant. * The subject has a diagnosis of any of the following disorders at the time of screening: pheochromocytoma; cardiac conditions including: congestive heart failure within the previous 6 months, myocardial infarction within the previous 6 months, symptomatic coronary artery disease, history of ventricular tachycardia, or uncontrolled cardiac arrhythmias; thyrotoxicosis; uncontrolled diabetes mellitus (uncontrolled defined as a HgbA1c greater than or equal to 10%); history of cerebrovascular accident, transient ischemic attack (TIA) or symptomatic carotid artery stenosis within the previous 6 months; history of coagulopathies; pulmonary hypertension; severe psychiatric disorders; renal failure (Creatinine equal to or greater than 2 times the upper limit of normal) * The subject has a concurrent chronic or acute illness, disability, or other condition that might confound the results of the tests and/or measurements administered in this trial, or that might increase the risk to the subject.