Conditions: Hypertension Pure Autonomic Failure Multiple System Atrophy
Keywords: supine Hypertension autonomic failure nitric oxide nebivolol
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 20
Healthy volunteers: no

Brief summary:
The purpose of this study is to evaluate the effect of the antihypertensive drug, nebivolol (Bystolic), compared to metoprolol (Lopressor) and sildenafil (Viagra) on blood pressure in patients with autonomic failure and supine hypertension.

Detailed description:
Nebivolol is distinct among beta-blockers by its ability to increase nitric oxide (NO) bioactivity. The contribution of this effect to the pharmacological actions of the drug, however, is difficult to ascertain in normal subjects because of the confounding contribution of the autonomic nervous system. Autonomic failure patients provide a unique model of hypertension devoid of autonomic modulation but sensitive to NO mechanisms. We propose to determine the effect of nebivolol on blood pressure in this patient population. A decrease in blood pressure will imply increased bioactivity of NO. Comparisons will be made with placebo, metoprolol (as a negative control) and sildenafil (as a positive control).

Arms:
arm 1: Placebo capsule arm 2: Nebivolol 5 mg capsule arm 3: Metoprolol tartrate 50 mg single oral dose arm 4: Sildenafil 25 mg single oral dose

Interventions: intervention 1: Placebo intervention 2: Nebivolol 5 mg intervention 3: metoprolol tartrate 50 mg intervention 4: Sildenafil25 mg
Intervention descriptions: intervention 1: Placebo capsule intervention 2: Nebivolol 5mg single oral dose intervention 3: metoprolol tartrate 50 mg single oral dose intervention 4: Sildenafil 25 mg single oral dose

Protocol document: