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(ĕp'ənĕf`rīn), hormonehormone,
secretory substance carried from one gland or organ of the body via the bloodstream to more or less specific tissues, where it exerts some influence upon the metabolism of the target tissue.
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 important to the body's metabolism, also known as adrenaline. Epinephrine, a catecholaminecatecholamine
, any of several compounds occurring naturally in the body that serve as hormones or as neurotransmitters in the sympathetic nervous system. The catecholamines include such compounds as epinephrine, or adrenaline, norepinephrine, and dopamine.
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, together with norepinephrinenorepinephrine
, a neurotransmitter in the catecholamine family that mediates chemical communication in the sympathetic nervous system, a branch of the autonomic nervous system.
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, is secreted principally by the medulla of the adrenal glandadrenal gland
or suprarenal gland
, endocrine gland (see endocrine system) about 2 in. (5.1 cm) long situated atop each kidney. The outer yellowish layer (cortex) of the adrenal gland secretes about 30 steroid hormones, the most important of which are aldosterone and
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. Heightened secretion caused perhaps by fear or anger, will result in increased heart rate and the hydrolysis of glycogen to glucose. This reaction, often called the "fight or flight" response, prepares the body for strenuous activity. The hormone was first extracted (1901) from the adrenal glands of animals by Jokichi Takamine; it was synthesized (1904) by Friedrich Stolz. Epinephrine is used medicinally as a stimulant in cardiac arrest, as a vasoconstrictor in shock, as a bronchodilator and antispasmodic in bronchial asthma, and to lower intra-ocular pressure in the treatment of glaucoma.


See B. B. Hoffman, Adrenaline (2013).


A hormone which is the predominant secretion from the adrenal medulla; also known as adrenalin, it has the structure shown. Epinephrine is a sympathomimetic substance; that is, it acts on tissue supplied by sympathetic nerves, and generally the effects of its action are the same as those of other nerve stimuli. Conversely, the stimulation of the splanchnic or visceral nerves will cause the rapid release of the hormone from the medullary cells of the adrenal gland. Thus, epinephrine plays an important role in preparing the organism to meet conditions of physiologic emergency.

When injected intravenously, epinephrine causes an immediate and pronounced elevation in blood pressure, which is due to the coincident stimulation of the action of the heart and the constriction of peripheral blood vessels. The chief metabolic changes following the injection of epinephrine are a rise in the basal metabolic rate and an increase of blood sugar. These effects of epinephrine are transitory. See Adrenal gland, Carbohydrate metabolism

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C9H13O3N A hormone secreted by the adrenal medulla that acts to increase blood pressure due to stimulation of heart action and constriction of peripheral blood vessels. Also known as adrenaline.
References in periodicals archive ?
No significant differences in croup score changes were found when heliox was compared with 30% oxygen (n=15, mild to moderate croup) and 100% oxygen with prn nebulized racemic epinephrine (n=29, moderate to severe croup).
Prospective randomized double-blind study comparing L-epinephrine and racemic epinephrine aerosols in the treatment of laryngotracheitis (croup).
Patients receiving racemic epinephrine at the first visit were more likely to return, regardless of the route of dexamethasone administration.
One recent study described a child with croup who developed a documented myocardial infarction while receiving a racemic epinephrine aerosol.
50,57] Epinephrine is generally more available than racemic epinephrine and less expensive.
The clinical efficacy of nebulized racemic epinephrine and albuterol in acute bronchiolitis.
Today, racemic epinephrine can be given on an outpatient basis, as long as patients can be observed for 2-4 hours after receiving the treatment.
Racemic epinephrine administered by nebulizer can quickly reverse airway obstruction in children with croup.
The three treatments for croup, humidified air, racemic epinephrine, and adrenal corticosteroids, are discussed in the sections that follow (Table 3).
saline (L-epinephrine [1:1000] administered by nebulizer may be used if racemic epinephrine is not available.
Racemic epinephrine (a mixture of equal amounts of the D- and L-isomers of epinephrine) works through its [alpha]-adrenergic effects, causing mucosal vasoconstriction that leads to decreased edema in the subglottic region of the larynx.
L-epinephrine (1:1000), which is more readily available, can be administered by nebulizer and is as effective as racemic epinephrine in treating upper airway obstruction caused by croup.