Due to potential competition with a post-marketing study requested by FDA

Evaluate the clinical efficacy and safety of droxidopa versus placebo over a 17 week (maximum) treatment period in patients with symptomatic NOH.

This is a multi-center, multi-national, randomized, parallel-group, placebo-controlled, double-blind study with a 17 week (maximum) treatment period consisting of an initial, open-label dose titration (up to 2 weeks), followed by a washout period (up to 3 weeks), followed by a 12 week treatment period on a stable dose.

Inclusion Criteria:

• 1. 18 years and older and ambulatory (defined as able to walk at least 10 meters);

  2. Clinical diagnosis of symptomatic orthostatic hypotension associated with Primary Autonomic Failure (PD, MSA and PAF), Dopamine Beta Hydroxylase Deficiency;

  3. At the Baseline visit (Visit 2), patients must demonstrate:

  1. a score of at least 4 or greater on the Orthostatic Hypotension Symptom Assessment (OHSA) Item #1;

  2. a fall of at least 20 mmHg in their systolic blood pressure, within 3 minutes of standing;

     4. Provide written informed consent to participate in the study and understand that they may withdraw their consent at any time without prejudice to their future medical care;

     Exclusion Criteria:

• 1. Score of 23 or lower on the mini-mental state examination (MMSE);

  2. Concomitant use of vasoconstricting agents for the purpose of increasing blood pressure;

  1. Patients taking vasoconstricting agents such as ephedrine, dihydroergotamine, or midodrine must stop taking these drugs at least 2 days or 5 half-lives (whichever is longer) prior to their baseline visit (Visit 2) and throughout the duration of the study;

     3. Known or suspected alcohol or substance abuse within the past 12 months (DSM-IV definition of alcohol or substance abuse);

     4. Women who are pregnant or breastfeeding;

     5. Women of child bearing potential (WOCP) who are not using at least one method of contraception with their partner;

     6. Male patients who are sexually active with a woman of child bearing potential (WOCP) and not using at least one method of contraception;

     7. Untreated closed angle glaucoma;

     8. Diagnosis of hypertension that requires treatment with antihypertensive medications (short-acting antihypertensives to treat nocturnal supine HTN are allowed in this study) Any significant uncontrolled cardiac arrhythmia;

     9. History of myocardial infarction, within the past 2 years;

     10. Current unstable angina;

     11. Congestive heart failure (NYHA Class 3 or 4);

     12. 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;

     13. Gastrointestinal condition that may affect the absorption of study drug (e.g. ulcerative colitis, gastric bypass);

     14. Any major surgical procedure within 30 days prior to the Baseline visit (Visit 2);

     15. Previously treated with droxidopa within 30 days prior to the Baseline visit (Visit 2);

     16. Currently receiving any other investigational drug or have received an investigational drug within 30 days prior to the Baseline visit (Visit 2);

     17. 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;

     18. The Investigator has the ability to exclude a patient if for any reason they feel the subject is not a good candidate for the study or will not be able to follow study procedures.