Adrenergic blocking agent

Adrenergic blocking agents are a class of drugs that exhibit its pharmacological action through inhibiting the action of the sympathetic nervous system (SNS) in the body. The sympathetic nervous system is an autonomic nervous system that we cannot control by will. It triggers a series of responses after the body releases chemicals named noradrenaline (norepinephrine) and adrenaline (epinephrine). These chemicals will act on adrenergic receptors, with subtypes alpha-1, alpha-2, beta-1, beta-2, and beta-3, which ultimately allow the body to trigger a fight-or-flight response to handle external stress. These responses include vessel constriction in general vessels whereas there is vasodilation in vessels that supply skeletal muscles or in coronary vessels. Additionally, heart rate and contractile force increases when the SNS is activated, which may be harmful to cardiac function as it increases metabolic demand.

Adrenergic blocking agents treat certain diseases through blocking the adrenergic receptor, preventing it from being activated by noradrenaline and adrenaline. As a result, it stops the body from producing the fight-or-flight response.