What is the role of Epinephrine (adrenaline)?

From the Guidelines

Epinephrine is the drug of choice for the treatment of anaphylaxis, with a recommended dose of 0.01 mg/kg, up to 0.3 mg in children, and 0.3 to 0.5 mg in adults, depending on the severity of the reaction. The role of epinephrine, also known as adrenaline, is crucial in emergency situations, particularly in the treatment of anaphylaxis, a severe and life-threatening allergic reaction. According to the most recent and highest quality study 1, epinephrine has been shown to increase survival to hospital discharge and improve return of spontaneous circulation (ROSC) in patients with out-of-hospital cardiac arrest.

Key Points

• Epinephrine is administered via intramuscular injection in the anterolateral thigh, which may achieve a more rapid and higher plasma concentration than subcutaneous or intramuscular injection in the arm 1.
• Delayed use of epinephrine may be ineffective, and fatal outcomes are often associated with delay or lack of administration of epinephrine 1.
• Patients with severe allergies should carry their prescribed epinephrine auto-injector at all times, check expiration dates regularly, and know how to use it properly 1.
• After administration, emergency medical help should be sought immediately, as the effects of epinephrine are temporary, lasting only 10-20 minutes.

Administration and Dosage

• The standard dose for anaphylaxis is 0.3-0.5 mg intramuscularly for adults, typically administered via an auto-injector like an EpiPen into the outer thigh 1.
• For children weighing 15-30 kg, the dose is reduced to 0.15 mg 1.
• Repeat dosing may be required for persistent or recurrent symptoms, and patients with cardiovascular disease should be given epinephrine for use in the event of an allergic reaction, despite concerns about epinephrine's cardiac effects 1.

Clinical Considerations

• Epinephrine functions by binding to alpha and beta adrenergic receptors throughout the body, triggering the fight-or-flight response that counteracts the life-threatening symptoms of anaphylaxis 1.
• The use of epinephrine in cardiac arrest has been shown to increase survival to hospital discharge and improve ROSC, although the difference in survival with favorable neurological outcome approached significance in the epinephrine group 1.

From the FDA Drug Label

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action Epinephrine acts on both alpha and beta-adrenergic receptors. 12. 2 Pharmacodynamics Through its action on alpha-adrenergic receptors, epinephrine lessens the vasodilation and increased vascular permeability that occurs during anaphylaxis, which can lead to loss of intravascular fluid volume and hypotension Through its action on beta-adrenergic receptors, epinephrine causes bronchial smooth muscle relaxation and helps alleviate bronchospasm, wheezing and dyspnea that may occur during anaphylaxis Epinephrine also alleviates pruritus, urticaria, and angioedema and may relieve gastrointestinal and genitourinary symptoms associated with anaphylaxis because of its relaxer effects on the smooth muscle of the stomach, intestine, uterus and urinary bladder Epinephrine increases glycogenolysis, reduces glucose up take by tissues, and inhibits insulin release in the pancreas, resulting in hyperglycemia and increased blood lactic acid Epinephrine causes mydriasis when administered parenterally.

The role of Epinephrine (adrenaline) is to:

• Act on both alpha and beta-adrenergic receptors to alleviate symptoms of anaphylaxis
• Lessen vasodilation and increased vascular permeability through its action on alpha-adrenergic receptors
• Cause bronchial smooth muscle relaxation and alleviate bronchospasm, wheezing, and dyspnea through its action on beta-adrenergic receptors
• Alleviate pruritus, urticaria, and angioedema and relieve gastrointestinal and genitourinary symptoms associated with anaphylaxis 2

From the Research

Role of Epinephrine (Adrenaline)

The role of epinephrine (adrenaline) is crucial in the treatment of various medical conditions, including:

• Anaphylaxis: Epinephrine is the mainstay of acute pharmacotherapy for anaphylaxis, a life-threatening allergic reaction 3, 4, 5
• Cardiac arrest: Epinephrine is used in cardiopulmonary resuscitation to treat cardiac arrest 6
• Allergic shock: Epinephrine is used to treat allergic shock, a condition characterized by a severe allergic reaction 3, 4

Administration and Dosage

The administration and dosage of epinephrine vary depending on the condition being treated:

• Anaphylaxis: The recommended dose is 0.3-0.5 mg, injected intramuscularly in the anterolateral aspect of the mid-thigh 3, 5
• Cardiac arrest: The standard dose is 1 mg, administered intravenously every 3-5 minutes 6
• Allergic shock: The dose and route of administration may vary, but epinephrine is often given intramuscularly or intravenously 4, 7

Importance of Prompt Administration

Prompt administration of epinephrine is critical in the treatment of anaphylaxis and other life-threatening conditions:

• Delayed administration of epinephrine can contribute to fatalities 5
• Epinephrine is most effective when given immediately after the onset of symptoms 5
• Junior doctors may be unsure about the proper administration and dosing of epinephrine, highlighting the need for education and training 4