Study of Midodrine and Droxidopa Effects on Abdominal Veins in Adults with Autonomic Failure and Orthostatic Hypotension

What this Trial Is About

Researchers are studying the effects of two medications, midodrine and droxidopa, on blood vessel function in the abdomen of patients who have autonomic failure and experience low blood pressure when standing orthostatic hypotension. This randomized, double-blind study involves patients with multiple system atrophy, pure autonomic failure, or Parkinson disease. The purpose is to understand how these drugs affect stroke volume during a head-up tilt test. The study enrolls about 34 participants who will be randomly assigned to receive either droxidopa or midodrine in a two-arm parallel design. Each participant will attend two study days spaced two days apart one day they will receive an active drug dose droxidopa 300 mg or midodrine 10 mg, and on the other day they will receive placebo. On each day, participants undergo two tilt table tests with measurements taken before and after drug administration, including blood pressure, heart rate, cardiac output, and venous capacitance. Abdominal compression may be applied during the second tilt test to further assess effects. Participants will be involved for about five days including screening and testing. During screening, medical history, physical exams, ECG, laboratory tests, and autonomic testing will be done. Throughout testing days, detailed monitoring and measurements are taken to evaluate drug effects on the cardiovascular system during body position changes. Researchers will assess stroke volume during head-up tilt as the primary outcome. Safety and symptom severity will also be monitored during the study period.

Effects of Midodrine and Droxidopa on Splanchnic Capacitance in Autonomic Failure