Adrenalin

Adrenalin, also called epinephrine, is a hormone and neurotransmitter in humans that belongs to the catecholamine family. It is produced by the adrenal medulla and released into the bloodstream in response to stress. The term adrenaline is still used in many regions as a common name for the drug form of epinephrine.

Biosynthesis occurs in chromaffin cells of the adrenal medulla, where tyrosine is converted to dopamine, norepinephrine, and finally epinephrine, which is stored in vesicles and released in response to stress. In circulation, epinephrine prepares tissues for action by mobilizing energy stores and improving blood flow to essential organs.

Epinephrine acts by binding to adrenergic receptors. Activation of beta-1 receptors increases heart rate and contractility; beta-2 receptors cause bronchodilation and vasodilation in skeletal muscle; alpha-1 receptor stimulation constricts peripheral vessels, raising blood pressure and reducing local bleeding.

In medicine, epinephrine is used to treat life-threatening conditions such as anaphylaxis and cardiac arrest. It can be given by intramuscular injection for severe allergic reactions or intravenously during resuscitation. When used with local anesthetics, it prolongs anesthesia and reduces bleeding. It is also employed in some respiratory and ocular procedures.

Pharmacokinetics and history: Epinephrine is rapidly metabolized by monoamine oxidase and catechol-O-methyltransferase, resulting in a short duration of action. The drug was isolated in 1901 by Jokichi Takamine, and its widely used name Adrenalin reflects early branding.