Antiadrenergic agents inhibit the activity of the sympathetic nervous system. They act by blocking adrenergic receptors in target organs or by inhibiting the synthesis, storage, or release of endogenous catecholamines (mainly norepinephrine). This class of medications is most commonly used for the treatment of ischemic heart disease and hypertension, although antiadrenergic agents may also be used for urinary retention secondary to benign prostatic hyperplasia and for psychiatric conditions such as anxiety disorders and post-traumatic stress disorder.
are discussed in detail in a separate article.
General mode of action
Inhibit alpha-1 receptors in smooth muscle →
- ↓ Vasoconstriction → ↓ blood pressure
- Relaxation of bladder neck muscles → ↓ bladder outlet obstruction and easier micturition
- Unopposed epinephrine binding to beta-adrenergic receptors →
- Through unknown mechanisms, alpha blockers can reduce nightmares secondary to PTSD.
- Inhibit alpha-1 receptors in smooth muscle →
- Inhibit mainly beta-1 receptors in the heart →
- Activate alpha-2 receptors in presynaptic sympathetic neurons of the central nervous system → ↑ negative feedback → ↓ catecholamine release (dopamine and norepinephrine) →
- Through unknown mechanisms, some alpha-2 adrenergic agonists improve symptoms in ADHD and Tourette syndrome.
Reserpine: Indole alkaloid used in the treatment of tardive dyskinesia, psychiatric disorders, and hypertension.
- Mode of action
- Side effects include parkinson-like syndrome, angina, bradycardia, peripheral edema, and depression
- Reserpine: Indole alkaloid used in the treatment of tardive dyskinesia, psychiatric disorders, and hypertension.
All drug groups that directly inhibit the sympathetic nervous system (i.e., alpha blockers, beta blockers, and drugs that reduce sympathetic tone) are treatment options for arterial hypertension!
Sympathetic blockers are usually used in antihypertensive combination regimens!