A Phase IV Study in Subjects With Neurogenic Orthostatic Hypotension

We are seeking male and female patients to voluntarily take part in a clinical research study. Patients must be aged 18 or older and diagnosed with symptomatic orthostatic hypotension (low blood pressure while in the upright position) due to Parkinson's disease, multiple system atrophy, pure autonomic failure or autonomic neuropathies (i.e. neurogenic orthostatic hypotension). Symptoms of low blood pressure include dizziness, lightheadedness, changes in vision and generalized weakness upon standing. The main effect of the drug being studied is to increase blood pressure in the upright position so symptoms will decrease. The purpose of this clinical study is to further assess the clinical effect of high dose midodrine hydrochloride (ProAmatine®), an approved treatment for orthostatic hypotension. During the course of the study, participants will receive either ProAmatine® or a placebo. Assessments will be made using questionnaires that measure symptom and activity levels. Blood pressure in the lying down, sitting and standing positions will be measured. Patients will also complete standing time assessments. They will be asked to remain standing without moving until they feel sufficiently lightheaded, or dizzy, or feel faint so that they would feel more comfortable sitting down.