From the Guidelines
No, epinephrine for anaphylaxis should be administered intramuscularly (IM), not subcutaneously (sub Q). The recommended dose is 0.01 mg/kg of a 1:1000 (1 mg/mL) solution to a maximum of 0.5 mg in adults and 0.3 mg in children, injected into the anterolateral thigh 1. This should be repeated every 5-15 minutes if symptoms persist. Intramuscular injection provides faster and more reliable absorption than subcutaneous administration during anaphylaxis when peripheral circulation may be compromised. After administering epinephrine, the patient should be placed in a supine position with legs elevated (unless respiratory distress prevents this), given supplemental oxygen if available, and emergency medical services should be called immediately. Additional supportive measures may include IV fluids for hypotension and H1 antihistamines and corticosteroids as adjunctive therapy, though these should never delay epinephrine administration.
Some key points to consider when administering epinephrine for anaphylaxis include:
- The importance of prompt administration, as failure to administer epinephrine early in the course of treatment has been repeatedly implicated in anaphylaxis fatalities 1
- The need for repeated dosing every 5-15 minutes if symptoms persist, as the effect of epinephrine is often short-lived 1
- The use of intramuscular injection into the anterolateral thigh, which provides higher and more rapid peak plasma levels of epinephrine compared to injections administered intramuscularly or subcutaneously in the arm 1
It is also important to note that while antihistamines and glucocorticoids are often used as adjunctive therapy in anaphylaxis, there is limited evidence to support their use, and they should never delay the administration of epinephrine 1. Overall, the key to successful management of anaphylaxis is prompt recognition and treatment with epinephrine, as well as supportive care and monitoring for potential complications.
From the FDA Drug Label
Adrenalin® is available as a single-use 1 mL vial and a multiple-use 30 mL vial for intramuscular and subcutaneous use. Emergency treatment of allergic reactions (Type I), including anaphylaxis, which may result from allergic reactions to insect stings, biting insects, foods, drugs, sera, diagnostic testing substances and other allergens, as well as idiopathic anaphylaxis or exercise-induced anaphylaxis.
The recommended administration route for epinephrine in the context of anaphylaxis is intramuscular. Although the label mentions that the drug is available for subcutaneous use, it does not explicitly state that subcutaneous administration is recommended for anaphylaxis. The intramuscular route is the preferred method for emergency treatment of anaphylaxis 2.
From the Research
Administration of Epinephrine in Anaphylaxis
- The administration of epinephrine is crucial in the treatment of anaphylaxis, and it should be given as soon as the diagnosis is suspected 3, 4, 5, 6.
- Epinephrine should be administered intramuscularly, into the anterolateral thigh, as the initial dose 3, 4, 5.
- Subcutaneous (sub Q) administration of epinephrine is not the recommended route for the initial dose in anaphylaxis 3, 4, 5.
- For patients unresponsive to repeated intramuscular injections, a continuous infusion of epinephrine may be started 3.
- Intravenous epinephrine may be used in patients in shock, either as a bolus or infusion, along with fluid resuscitation 4.
Importance of Prompt Administration
- Delaying the administration of epinephrine can result in increased patient morbidity and mortality 3.
- Antihistamines and corticosteroids are second-line medications and should never be given in lieu of, or prior to, epinephrine 3, 6.
- The administration of adjunct medications, such as histamine H1 and H2 antagonists, corticosteroids, beta2 agonists, and glucagon, should only be considered after epinephrine administration 5, 6.