Epinephrine pharmacological properties

Adrenergic receptors (ARs) are the interface between the sympathetic nervous system and the cardiovascular system. ARs include two major subtypes, a and P, based on their pharmacological properties and molecular structure. The a-ARs consist of three ar AR subtypes and three o -ARs. P-ARs are also classified into three well-characterized subtypes Pb p2, and P3. Although they respond to the same hormones (norepinephrine and epinephrine), a- and P-ARs differ significantly in the types of cellular responses they mediate. 

I. Pharmacology. Epinephrine is an endogenous catecholamine with alpha- and beta-adrenergic agonist properties, used primarily in emergency situations to treat anaphylaxis or cardiac arrest. Beneficial effects include inhibition of histamine release from mast cells and basophils, bronchodilation, positive inotropic effects, and peripheral vasoconstriction. Epinephrine is not active after oral administration. Subcutaneous injection produces effects within 5-10 minutes, with peak effects at 20 minutes. Intravenous or inhalational administration produces much more rapid onset. Epinephrine is rapidly inactivated in the body, with an elimination half-life of 2 minutes. 

This ability to chelate heavy metal ions has been brought forward to account for some pharmacological activities shown by flavonoid compounds. Clark and Geissman showed, however, that the potentiation of effects of epinephrine by flavonoid compounds, tested upon an isolated smooth muscle preparation and attributable to the metal-chelating properties of the compounds, did not correspond with their vitamin-P activities as reported in the literature (c/. p. 275). 

Epinephrine sensitizes the nociceptors to the pain producing properties of bradykinin in man. Some clinical-pharmacological implications are considered. 

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