Author: Brian Wu PhD. MD Candidate, Keck School of Medicine, Los Angeles, USA; Chief Editor: Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand, August 2015.
Adrenaline is a hormone derived from tyrosine, an amino acid. Adrenaline is also spelt adrenalin, and in North America is known by the name epinephrine. Adrenaline/epinephrine, noradrenaline/norepinephrine and dopamine are classified as catecholamines.
Epinephrine and norepinephrine are stress hormones and function as part of the 'fight or flight' response.
Adrenaline is produced by the chromaffin cells in the medulla of the adrenal glands and is released in response to a stressor or perceived threat. This stressor can be emotional, physical or environmental.
The steps to the adrenaline response and release are as follows:
The release of adrenaline activates specific physiological reactions, which are intended to prepare the body to respond to the perceived stressor or threat.
The responses include:
Adrenaline is a first-line treatment for anaphylaxis, an IgE-mediated, severe allergic reaction caused by the release of mediators from mast cells that have been previously sensitised to a specific allergen. Anaphylaxis is characterised by:
Due to its physiological effects, adrenaline is able to reverse anaphylaxis by:
Other uses of adrenaline include its use in local anaesthetic to enhance the duration of anaesthesia and to reduce the chance of haemorrhage. It is also used as an adrenergic receptor stimulant during cardiopulmonary resuscitation (CPR).
While adrenaline is considered to be a life-saving medication, there are risk involves with its use, especially if it is administered intravenously or in high dosages. These risks are of particular concern in the following circumstances:
Prolonged or repeated use of adrenaline has the potential to cause cardiac hypertrophy due to stimulation of mitogen-activated proteins and an increase in myocardial cells.
Knowledge of self-administration of adrenaline to treat anaphylactic shock is critical for those with a history of severe allergic reactions. The procedure of self-administering adrenaline using the Epipen® device is as follows:
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