A Clinical Study of Patients With Symptomatic NOH to Assess Sustained Effects of Droxidopa Therapy

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 PrimaryAutonomic Failure (PD, MSA and PAF), Dopamine Beta Hydroxylase Deficiency;

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

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

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

6. Provide written informed consent to participate in the study and understandthat they may withdraw their consent at any time without prejudice to theirfuture 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 bloodpressure;

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

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

5. Women who are pregnant or breastfeeding;

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

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

8. Untreated closed angle glaucoma;

9. Diagnosis of hypertension that requires treatment with antihypertensivemedications (short-acting antihypertensives to treat nocturnal supine HTN areallowed in this study) Any significant uncontrolled cardiac arrhythmia;

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

11. Current unstable angina;

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

13. History of cancer within the past 2 years other than a successfully treated,non-metastatic cutaneous squamous cell or basal cell carcinoma or cervical cancerin situ;

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

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

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

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

18. Any condition or laboratory test result, which in the Investigator'sjudgment, might result in an increased risk to the patient, or would affect theirparticipation in the study;

19. The Investigator has the ability to exclude a patient if for any reason theyfeel the subject is not a good candidate for the study or will not be able tofollow study procedures.