adrenalinaepinefryna

Adrenalinaepinefryna, commonly known as adrenaline or epinephrine, is a catecholamine hormone and neurotransmitter produced mainly by the adrenal medulla and certain sympathetic neurons. It functions as both a circulating hormone and a neurotransmitter, mediating the body's rapid “fight-or-flight” response to stress. Its release increases heart rate and cardiac contractility, raises blood pressure through vasoconstriction, dilates airways, and stimulates metabolic processes such as glycogenolysis and lipolysis, thereby increasing glucose and energy availability for muscles.

Biochemically, adrenaline is synthesized from the amino acid tyrosine through a series of steps producing DOPA, dopamine, norepinephrine, and finally epinephrine via the enzyme phenylethanolamine N-methyltransferase (PNMT) in chromaffin cells of the adrenal medulla. It is stored in secretory vesicles and released into the bloodstream or synapses in response to sympathetic stimulation.

Adrenaline exerts its effects by activating adrenergic receptors (alpha and beta subtypes). Beta-1 receptors increase heart rate and contractility; beta-2 receptors promote bronchodilation and vasodilation in certain vascular beds; alpha-1 receptors cause vasoconstriction in others. The net effect is enhanced blood flow to skeletal muscles, improved airway patency, and mobilization of energy stores.

Medical uses include treatment of anaphylaxis and other severe allergic reactions, cardiac arrest and certain shock states, and as a local vasoconstrictor with anesthetics to prolong effect. It is commonly administered intramuscularly (e.g., auto-injectors for anaphylaxis), intravenously, or topically.

Pharmacokinetics involve rapid onset and a short half-life, with metabolism by monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT). Potential adverse effects include tachycardia, hypertension, arrhythmias, anxiety, and tremor, with caution in patients with certain cardiovascular or thyroid conditions or when combined with MAO inhibitors.