<unk> s are a class of drugs that exhibit its pharmacological action through inhibiting the action of the sympathetic nervous system in the body. The sympathetic nervous system(SNS) is an autonomic nervous system, in which we can not control by will. It triggers a series of responses after the body releases chemicals named noradrenaline and epinephrine. These chemicals will act on adrenergic receptors, with subtypes Alpha-1, Alpha-2, Beta-1, Beta-2, 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, the heart rate and contractile force increase when SNS is activated, which may be harmful to cardiac function as it increases metabolic demand.<unk> s treat certain diseases through<unk>  the adrenergic receptor, preventing it from being activated by noradrenaline and epinephrine. As a result, it stops the body from producing the "fight-or-flight" responses.
Adrenergic blocking agent
Adrenergic release inhibitor
Norepinephrine releasing agent
Norepinephrine–dopamine releasing agent
Chaotropic agent
Serotonin–norepinephrine releasing agent
Serotonin releasing agent
Serotonin–norepinephrine–dopamine releasing agent