Epinephrine, Not Promethazine (Avil), is the First-Line Treatment for Pediatric Anaphylaxis
Epinephrine, not promethazine (Avil), is the recommended first-line treatment for pediatric anaphylaxis, with a dose of 0.01 mg/kg up to 0.3 mg administered intramuscularly into the lateral thigh. 1
Correct Medication for Anaphylaxis
- Epinephrine is the primary medical therapy for anaphylaxis and must be administered promptly 1
- Antihistamines like promethazine (Avil) should not be substituted for epinephrine as they do not reverse anaphylaxis 2, 3
- H1-antihistamines may be used as adjunctive treatment only after epinephrine administration 2
Epinephrine Dosing in Pediatric Anaphylaxis
- The recommended dose is 0.01 mg/kg up to a maximum of 0.3 mg in prepubertal children 1, 2
- For auto-injectors, use 0.15 mg for children weighing 10-25 kg and 0.3 mg for children weighing ≥25 kg 1, 2
- Intramuscular injection into the lateral thigh (vastus lateralis muscle) is the preferred route 1
Administration Considerations
- Epinephrine reaches peak plasma concentration in approximately 8 ± 2 minutes when injected intramuscularly in the vastus lateralis 1
- If needed, a second dose can be administered 5-15 minutes after the first dose if symptoms persist 1, 2
- 6-19% of pediatric patients treated with epinephrine require a second dose 1
Special Populations and Considerations
- For infants weighing less than 15 kg, in the absence of a suitable alternative, the 0.15 mg auto-injector is recommended despite being higher than the calculated dose 3
- The Canadian Society of Allergy and Immunology recommends using the 0.15 mg auto-injector for children weighing less than 15 kg, as adverse effects are expected to be mild and transient compared to the risk of not receiving epinephrine 3
- For infants, drawing up the dose from a vial is an alternative but presents challenges in accuracy and time delay 1
Important Caveats
- Delayed administration of epinephrine is associated with poor outcomes and increased risk of fatality 2
- Intravenous administration carries risks of dilution errors and dosing errors and should be reserved for severe cases not responding to IM epinephrine or in hospital settings 1
- Auto-injector needle length may be too long for some infants (risk of intraosseous injection) and too short for some obese adolescents (risk of subcutaneous rather than intramuscular injection) 4, 5
Adjunctive Treatments
- After epinephrine administration, diphenhydramine 1-2 mg/kg or 25-50 mg/dose parenterally may be given 1
- Consider ranitidine 1 mg/kg intravenously for additional histamine blockade 1
- For bronchospasm resistant to epinephrine, nebulized albuterol 2.5-5 mg in 3 mL saline may be used 1
Remember that while promethazine (Avil) may have a role in managing allergic reactions, it is not the first-line treatment for anaphylaxis and should never replace epinephrine in the management of anaphylaxis.