Adrenergic agonist

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An adrenergic 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 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, and agonists vary in specificity between these receptors, and may be classified respectively. However, there are also other mechanisms of adrenergic agonism. Epinephrine and norepinephrine are endogenous and broad-spectrum. More selective agonists are more useful in pharmacology.

Contents 1 α1 agonists 2 α2 agonists 3 β1 agonists 4 β2 agonists 5 Other mechanisms 6 See also 7 External links

[edit] α₁ agonists

Main article: Alpha-1 adrenergic receptor#agonists

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

• Methoxamine
• Methylnorepinephrine
• Oxymetazoline
• Phenylephrine

[edit] α₂ agonists

Main article: Alpha-2 adrenergic receptor#agonists

α₂ agonists: inhibits adenylyl cyclase activity. (reduce brainstem vasomotor center-mediated SNS activation; used as antihypertensives, sedatives & treatment of opiate & alcohol withdrawal symptoms). Selected examples are:

• Clonidine (mixed alpha2-adrenergic and imidazoline-I1 receptor agonist)
• Guanfacine (preference for alpha2A-subtype of adrenoceptor)
• Guanabenz (most selective agonist for alpha2-adrenergic as opposed to imidazoline-I1)
• Guanoxabenz (metabolite of guanabenz)
• Guanethidine (periferal alpha2-receptor agonist)

[edit] β₁ agonists

Main article: Beta-1 adrenergic receptor#agonists

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

• Dobutamine
• Isoproterenol (β₁ and β₂)

[edit] β₂ agonists

Main article: Beta-2 adrenergic receptor#agonists

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

• salbutamol (albuterol in USA)
• Fenoterol
• Formoterol
• Isoproterenol (β₁ and β₂)
• Metaproterenol
• Salmeterol
• Terbutaline
• Clenbuterol

[edit] Other mechanisms

• Indirect action
  • Amphetamine
  • Tyramine
• Mixed action
  • Ephedrine

[edit] See also

• Adrenergic receptor

[edit] External links

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

v • d • e Cardiac stimulants excluding cardiac glycosides (C01C) Adrenergic and dopaminergic agents Etilefrine • Isoprenaline • Norepinephrine • Dopamine • Norfenefrine • Phenylephrine • Dobutamine • Oxedrine • Metaraminol • Methoxamine • Mephentermine • Dimetofrine • Prenalterol • Dopexamine • Gepefrine • Ibopamine • Midodrine • Octopamine • Fenoldopam • Cafedrine • Arbutamine • Theodrenaline • Epinephrine Phosphodiesterase inhibitors (PDE3I) Amrinone • Milrinone • Enoximone • Bucladesine Other cardiac stimulants Angiotensinamide • Xamoterol • Levosimendan

v • d • e Receptor agonists, antagonists, and reuptake inhibitors BA/M: 5-HT (serotonin) receptor Serotonin receptor agonist • Serotonin antagonist (5-HT3) • Serotonin uptake inhibitor (SSRI) BA/M: Dopamine receptor Dopamine agonist • Dopamine antagonist • Dopamine reuptake inhibitor BA/M: Adrenergic receptor Adrenergic agonist (Alpha, Beta2) • Adrenergic antagonist (Alpha, Beta) • Adrenergic uptake inhibitor BA/M: Histamine receptor Histamine agonist • Histamine antagonist (H1, H2) Acetylcholine receptor Cholinergic (Muscarinic, Nicotinic) • Anticholinergic (Muscarinic, Nicotinic) • Acetylcholinesterase inhibitor AA: GABA receptor GABA agonist • GABA antagonist AA: Glutamate receptor NMDA receptor (NMDA receptor antagonist)