Sympatholytic drugs

Sympatholytic agents inhibit the activity of the sympathetic nervous system, which is mediated by epinephrine and norepinephrine. They act primarily by blocking the postsynaptic adrenergic receptors (alpha and beta receptor antagonism) in target organs or by inhibiting the synthesis and storage of endogenous catecholamines (mainly norepinephrine). A sympatholytic effect can also be achieved via stimulation of the presynaptic alpha-2 receptor with an alpha-2 agonist, which inhibits the release of catecholamines. Sympatholytic drugs are most commonly used in the treatment of ischemic heart disease and hypertension but may also be used for urinary retention secondary to benign prostatic hyperplasia and for psychiatric conditions such as anxiety disorders and posttraumatic stress disorder.

Beta receptor antagonists are discussed in detail in a separate article.

All sympatholytic drugs inhibit the activity of the sympathetic nervous system via one of the following mechanisms:

• Inhibition of catecholamine receptors
• Inhibition of the production, storage, and/or release of catecholamines (especially norepinephrine)

All drug groups that directly inhibit the sympathetic nervous system (i.e., alpha receptor antagonists, beta receptor antagonists, and drugs that reduce sympathetic tone) are treatment options for arterial hypertension.

Alpha receptor antagonists are usually only second-line drugs for the treatment of hypertension since they do not improve prognosis. They are predominantly used in combination regimens.