adrenergic agonist

An adrenergic is a drug, or other substance, which has effects similar to, or the same as, epinephrine (adrenaline). Alternatively, it may refer to something which is susceptible to epinephrine, or similar substances, such as a biological receptor (specifically, the adrenergic receptors). Beta blockers block the action of epinephrine and norepinephrine in the body. Adrenergic drugs either stimulate a response (agonists) or inhibit a response (antagonists). The five categories of adrenergic receptors are: α₁, α₂, β₁, β₂, and β₃.

-α₁ agonists: stimulates phospholipase C activity. (vasoconstriction and mydriasis; used as vasopressors, nasal decongestants & eye exams).β₁

-α₁ antagonists: inhibits adenylyl cyclase activity. (reduce brainstem vasomotor center-mediated SNS activation; used as antihypertensives, sedatives & treatment of opiate & alcohol withdrawal symptoms).

-β₁ agonists: stimulates adenylyl cyclase activity; opening of calcium channel. (cardiac stimulants; used to treat cardiogenic shock, acute heart failure, bradyarrhythmias).

-β₂ agonists: stimulates adenylyl cyclase activity; closing of calcium channel (smooth muscle relaxants; used to treat asthma and COPD).

List of adrenergic agonist drugs

Direct-acting

Epinephrine and norepinephrine are endogenous and broad-spectrum. More selective agonists are more useful in pharmacology. These include:

• Albuterol (β₂)
• Clonidine (α₁)
• Dobutamine (β₁)
• Formoterol (β₂)
• Isoproterenol (β₁ and β₂)
• Metaproterenol (β₂)
• Methoxamine (α₁)
• Methylnorepinephrine (α₁)
• Oxymetazoline (α₁)
• Phenylephrine (α₁)
• Salmeterol (β₂)
• Terbutaline (β₂)

Indirect-acting

• Amphetamine
• Tyramine

Mixed action

• Ephedrine

See also

• Adrenergic receptor

External links

• Virtual Chembook article on adrenergic drugs
• MeSH adrenergic+agonists

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