An<unk>  is a drug, or other substance, which has effects similar to, or the same as, epinephrine (adrenaline). Thus, they are a kind of sympathomimetic agents. Alternatively, it may refer to something which is susceptible to epinephrine, or similar substances, such as a biological receptor (specifically, the<unk>  receptors).
Beta blockers block the action of epinephrine and norepinephrine in the body.<unk>  drugs either stimulate a response (agonists) or inhibit a response (antagonists). The five categories of<unk>  receptors are: α1, α2, β1, β2, and β3, and agonists vary in specificity between these receptors, and may be classified respectively. However, there are also other mechanisms of<unk> . Epinephrine and norepinephrine are endogenous and broad-spectrum. More selective agonists are more useful in pharmacology.
Adrenergic agonist
Alpha-adrenergic agonist
Beta-adrenergic agonist
Muscarinic agonist
Dopamine agonist
Muscarinic antagonist
Aldosterone antagonist
Serotonin antagonist