Overview

Epinephrine, commonly called adrenaline, is both a naturally occurring hormone and a widely used emergency drug. As a signaling chemical it functions as a catecholamine produced primarily by the adrenal glands. In clinical contexts it is administered as a medication to reverse life‑threatening allergic reactions, support circulation in cardiac arrest, and for other urgent indications. The term hormone emphasizes its role in systemic regulation, while its rapid receptor actions resemble those of a neurotransmitter.

Physiological actions and characteristics

Epinephrine is synthesized from the amino acid tyrosine and belongs to the catecholamine family. It acts on multiple adrenergic receptors (alpha and beta subtypes), producing a coordinated pattern of effects that prepare the body for rapid activity: increased heart rate and contractility, constriction of many blood vessels, dilation of bronchial airways, pupil dilation, and metabolic shifts such as increased glucose availability. These responses are often described as part of the "fight or flight" reaction. Its chemical name and roots reflect anatomy: the modern names derive from the Latin ad‑ + renes and the Greek epi‑ + nephros, both referring to location on or near the kidney.

Medical uses and administration

  • First‑line treatment for anaphylaxis, typically given by intramuscular injection (auto‑injectors are common).
  • Intravenous or intraosseous use during cardiopulmonary resuscitation to support coronary and cerebral perfusion.
  • Adjunct in some cases of severe asthma or bronchospasm, and as a vasoconstrictor to prolong local anesthetic effect or reduce bleeding.

Formulations include prefilled auto‑injectors, ampoules for intravenous use, and dilute solutions for topical or inhaled applications. Dose, route, and concentration vary with indication and setting.

History, names and common terms

Epinephrine was isolated and characterized in the late 19th and early 20th centuries; notable early work on isolation is attributed to chemists who prepared the active extract used in medicine. The two common names — epinephrine and adrenaline — are used interchangeably in many places; usage varies by country and by regulatory convention. In everyday clinical speech the drug is often abbreviated as "epi" and is pronounced "eh‑pee" in English medical settings.

Safety, side effects and distinctions

Epinephrine acts powerfully and quickly, so adverse effects can include rapid heart rate, elevated blood pressure, palpitations, anxiety, headache, and in some cases arrhythmias. Careful dosing is required, especially in people with cardiovascular disease. It is distinct from but related to norepinephrine (noradrenaline), which has a different balance of receptor effects and clinical uses. Because of its central role in emergency care, epinephrine remains a core drug in resuscitation algorithms and allergy management, and its availability and correct use can be life‑saving.

For concise clinical guidance and protocols, refer to professional resources and institution‑specific policies rather than this summary. More on hormones and medication details can be found through medical references and guidelines.