Source: Medicines & Healthcare Products Regulatory Agency (GB) Revision Year: 2025 Publisher: Macarthys Laboratories Ltd, T/A Martindale Pharma, Bampton Road, Harold Hill, Romford, Essex, England, RM3 8UG
Pharmacotherapeutic group: adrenergic and dopaminergic agents, adrenaline
ATC code: C01CA24
Adrenaline is a naturally occurring catecholamine secreted by the adrenal medulla in response to exertion or stress.
It is a sympathomimetic amine which is a potent stimulant of both alpha- and beta-adrenergic receptors and its effects on target organs are therefore complex. It is used to provide rapid relief of hypersensitivity reactions to allergies or to idiopathic or exercise-induced anaphylaxis. Adrenaline causes glucose to be released into circulation, oxygen consumption is increased. Blood flow to the kidneys, mucosa and skin is reduced.
Adrenaline has a strong vasoconstrictor action through alpha-adrenergic stimulation. This activity counteracts the vasodilatation and increased vascular permeability leading to loss of intravascular fluid and subsequent hypotension, which are the major pharmacological features in anaphylactic shock.
Adrenaline stimulates bronchial beta-adrenergic receptors and has a powerful bronchodilator action. Adrenaline also alleviates pruritus, urticaria and angioedema associated with anaphylaxis.
The overall effect of adrenaline depends on the dose used, and may be complicated by the homeostatic reflex responses.
Adrenaline has a rapid onset of action after intramuscular administration and in the shocked patient its absorption from the intramuscular site is faster and more reliable than from the subcutaneous site. The plasma half-life is about 2-3 minutes. However, when given by subcutaneous or intramuscular injection, local vasoconstriction may delay absorption so that the effects may last longer than the half-life suggests.
Adrenaline is rapidly inactivated in the body, mostly in the liver by the enzymes catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO).
Much of a dose of adrenaline is excreted as metabolites in urine. The onset of action and peak effect after injection is rapid, and the duration short (1-2 hours).
Elimination is mainly via metabolism of the liver and sympathetic nerve endings, with a small amount excreted unchanged in the urine.
No further relevant information other than that which is included in other sections of the Summary of Product Characteristics.
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