Safety and Efficacy of L-NAME and Midodrine to Increase MAP
| Status: | Completed |
|---|---|
| Conditions: | Cardiology, Hospital, Orthopedic |
| Therapuetic Areas: | Cardiology / Vascular Diseases, Orthopedics / Podiatry, Other |
| Healthy: | No |
| Age Range: | 18 - 65 |
| Updated: | 11/30/-0001 |
| Start Date: | May 2010 |
| End Date: | June 2014 |
| Contact: | Christina Yen, BS |
| Email: | christina.yen@va.gov |
| Phone: | (718) 584-9000 |
Safety and Efficacy of L-NAME and Midodrine to Increase MAP in Persons With Tetraplegia
After a spinal cord injury the brain is no longer completely in control of the body below
the level of injury. This affects many organs and systems in the body, we are interested in
understanding how a spinal cord injury affects blood pressure and blood flow to the brain.
We are going to study blood pressure while the person is seated in a wheelchair before and
after we give the subject medications which should increase blood pressure in a laboratory
setting and over the course of a normal day in persons with spinal cord injury.
Blood pressure regulation is compromised in persons with tetraplegia due to
de-centralization of sympathetic cardiovascular control, associated with hypotension during
upright positioning (7, 10, 18, 33). An alpha receptor agonist (midodrine hydrochloride)
has been reported to raise blood pressure in persons with tetraplegia (25, 26, 30).
Midodrine is the only drug that is presently available to treat orthostatic hypotension. In
the clinical armamentarium, it is always beneficial to have agents from multiple drug
classes to treat a condition. In the treatment of hypertension, several classes of drugs may
be prescribed to lower blood pressure, alone or in combination. The clinician and patient
would benefit if another class of drug, with a totally separate mechanism of action, were
available to treat orthostatic hypotension. A nitric oxide synthase inhibitor (NOSi),
nitro-L-arginine methyl ester (L-NAME), has been shown by our group to "normalize" blood
pressure in persons with tetraplegia (32). The safety and efficacy of these two
hypertensive agents has not been investigated or compared in persons with chronic
tetraplegia. Although the mechanism of action of each of these agents is appreciated, the
relative cardiovascular effect in persons with SCI compared with controls is not known. The
study will determine the efficacy and safety of these two medications at restoring mean
arterial pressure (MAP) during daily activities in persons with chronic tetraplegia.
Furthermore, the implication of restoring MAP to normal levels (80 10 mmHg) in individuals
with tetraplegia on cardiovascular, autonomic, hormonal and cognitive function.
Inclusion Criteria:
Spinal Cord Injured Subjects:
- chronic spinal cord injury (1 year post injury) with a seated MAP of 65mmHg (almost
all individuals with tetraplegia demonstrate this)
- Male or female with an age of 18 - 65 years
Control Subjects:
- Male or female with an age of 18 - 65 years
Exclusion Criteria:
Spinal Cord Injured Subjects:
- acute illness
- cardiovascular disease
- renal disease
- medications that affect the cardiovascular system
Control Subjects:
- acute illness
- cardiovascular disease
- renal disease
- medications that affect the cardiovascular system
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