Epinephrine

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Epinephrine
Systematic (IUPAC) name
4-(1-hydroxy- 2-(methylamino)ethyl)benzene-1,2-diol
Identifiers
CAS number	51-43-4
ATC code	A01 AD01 B02 BC09 C01 CA24 R01 AA14 R03 AA01 S01 EA01
PubChem	838
DrugBank	APRD00450
Chemical data
Formula	C₉H₁₃N O₃
Mol. weight	183.204 g/mol
Pharmacokinetic data
Bioavailability	Nil (oral)
Metabolism	adrenergic synapse (MAO and COMT)
Half life	2 minutes
Excretion	n/a
Therapeutic considerations
Pregnancy cat.	A(AU) C(US)
Legal status	S4(AU) POM(UK) ℞-only(US)
Routes	IV, IM, endotracheal

"Adrenaline" redirects here. For other uses, see Adrenaline (disambiguation).

Epinephrine (INN) (IPA: [ˌɛpɪˈnɛfrən]) or adrenaline (BAN) (IPA: [əˈdrɛnələn]), sometimes spelled "epinephrin" or "adrenalin" respectively, is a hormone. Epinephrine is a catecholamine, a sympathomimetic monoamine derived from the amino acids phenylalanine and tyrosine. The Latin roots ad-+renes and the Greek roots epi-+nephros both literally mean "on/to the kidney" (referring to the adrenal gland, which secretes epinephrine). Epinephrine is sometimes shortened to epi in medical jargon. Epinephrine is now also used in EpiPens and Twinjects. EpiPens are long narrow auto-injectors that administer epinephrine, Twinjects are similair but contain two doses of epinephrine. It should be noted that though both EpiPen and Twinject are trademark names, common usage of the terms are drifting toward the generic context of any epinephrine autoinjector.

In May 1886, William Bates reported the discovery of a substance produced by the adrenal gland in the New York Medical Journal. Epinephrine was isolated and identified in 1895 by Napoleon Cybulski, a Polish physiologist. The discovery was repeated in 1897 by John Jacob Abel. Jokichi Takamine discovered the same hormone in 1900, without knowing about the previous discovery. It was first artificially synthesized in 1904 by Friedrich Stolz.

1 Regulation
2 Pharmacology
3 Terminology
4 See also
5 References
6 External links

[edit] Regulation

Epinephrine release is stimulated by the sympathetic nervous system. As the adrenal medulla is essentially a modified sympathetic ganglion, it is activated by preganglionic sympathetic fibers which secrete acetylcholine, activating nicotinic acetylcholine receptors on the adrenal medullary cells, causing them to secrete epinephrine.

Cortisol, a product of chronic sympathetic nervous system activation, also enhances epinephrine production by increasing the synthesis of phenol O-methyltransferase (POMT), the adrenal medullary enzyme responsible for the conversion of norepinephrine into epinephrine.

[edit] Pharmacology

Epinephrin binds its receptor, that associates with an heterotrimeric G protein. The G protein associates with adenylate cyclase that converts ATP to cAMP, spreading the signal (more details...)

Epinephrine's actions are mediated through adrenergic receptors (sometimes referred to as adrenoceptors).

It binds to α₁ receptors of liver cells, which activate inositol-phospholipid signaling pathway, signaling the phosphorylation of insulin, leading to reduced ability of insulin to bind to its receptors.

Epinephrine also activates β-adrenergic receptors of the liver and muscle cells, thereby activating the adenylate cyclase signaling pathway, which will in turn increase glycogenolysis. β₂ receptors are found primarily in skeletal muscle blood vessels where they do indeed trigger vasodilation. However Alpha receptors are found in most smooth muscles and splanchnic vessels, and epinephrine triggers vasoconstriction in those vessels. Thus, depending on the patient, administration of epinephrine may raise or lower blood pressure, depending whether or not the net increase or decrease in peripheral resistance can balance the positive inotropic and chronotropic effects of epinephrine on the heart.

[edit] Terminology

Although widely referred to as "adrenaline" outside of the US, and the lay public worldwide, the USAN and INN for this chemical is "epinephrine" because "adrenaline" bore too much similarity to the Parke, Davis & Co trademark "adrenalin" (without the "e") which was registered in the US.

The BAN and EP term for this chemical is "adrenaline", and is indeed now one of the few differences between the INN and BAN systems of names.

Amongst US health professionals the term epinephrine is generally used over adrenaline. However, it should be noted that when referring to pharmaceuticals that mimic the actions of epinephrine/adrenaline their receptor sites are universally referred to as "adrenergics".

Epinephrine also known as adrenaline can be found in nature in the R form; however, racemic mixtures of the molecule can be used if its chirality is destroyed.