What is the recommended medication management for anaphylaxis?

Medication Management for Anaphylaxis

Epinephrine administered intramuscularly (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) into the anterolateral thigh is the first-line treatment for anaphylaxis. 1

First-Line Treatment: Epinephrine

• Epinephrine is the cornerstone of anaphylaxis management and the only first-line medication that should be administered promptly once anaphylaxis is suspected 2
• Administer epinephrine intramuscularly in the anterolateral thigh at the following doses:
  • Adults: 0.3-0.5 mg (1:1000 concentration) 3
  • Children: 0.01 mg/kg (1:1000 concentration) to a maximum of 0.3 mg 1
• Epinephrine can be repeated every 5-15 minutes as needed if symptoms persist 3
• Intramuscular injection in the lateral thigh is the preferred route for first-aid treatment due to more favorable pharmacokinetics compared to subcutaneous administration 1, 4

Autoinjector Dosing Recommendations

• For patients at risk of anaphylaxis, autoinjectors should be prescribed in the following doses:
  • 0.15 mg autoinjector for children weighing 10-25 kg (22-55 lb) 1
  • 0.30 mg autoinjector for individuals weighing approximately 25 kg (55 lb) or more 1
  • 0.1 mg autoinjector for infants (where available) 1
• In settings where a 0.1 mg auto-injector is not available, a 0.15 mg dose is appropriate for infants weighing >7.5 kg 1
• All patients at risk for anaphylaxis should carry 2 epinephrine autoinjectors and be properly trained in their use 2

Management of Severe or Refractory Anaphylaxis

• For persistent symptoms after initial epinephrine, consider intravenous epinephrine:
  • For Grade II reactions: IV epinephrine 20 μg 3
  • For Grade III reactions: IV epinephrine 50-100 μg 3
  • For Grade IV reactions: IV epinephrine 1 mg (following advanced life support guidelines) 3
• For refractory cases, consider epinephrine infusion (0.05-0.1 μg/kg/min) when more than three epinephrine boluses have been administered 3
• Administer crystalloid fluid bolus: 500 ml for Grade II reactions, 1 L for Grade III reactions, escalating to 20-30 ml/kg for refractory cases 3
• For persistent hypotension, add vasopressors such as norepinephrine (0.05-0.5 μg/kg/min), phenylephrine, or metaraminol 3
• For patients on beta-blockers with refractory symptoms, administer IV glucagon 1-2 mg 3

Second-Line Treatments

• Antihistamines are adjunctive therapy for cutaneous symptoms but should never be administered before or in place of epinephrine 1
• After adequate epinephrine and fluid resuscitation, consider:
  • H1 antihistamines: chlorphenamine or diphenhydramine 25-50 mg IV 3
  • H2 antihistamines: ranitidine 50 mg IV in adults (1 mg/kg in children) 3
  • Systemic glucocorticosteroids for patients with history of idiopathic anaphylaxis, asthma, or severe/prolonged anaphylaxis 3

Post-Anaphylaxis Management

• Observe patients in a monitored area for a minimum of 6 hours or until stable and symptoms are regressing 3
• Obtain mast cell tryptase samples: first at 1 hour after reaction onset, second at 2-4 hours, and baseline sample at least 24 hours post-reaction 3
• Arrange referral to an allergist for future investigation 3

Important Considerations and Pitfalls

• Delays in epinephrine administration may be fatal - it should be given immediately upon evidence of anaphylaxis 5
• Do not use antihistamines or corticosteroids as first-line treatment instead of epinephrine 3
• Avoid intravenous administration of epinephrine in non-arrest situations without appropriate monitoring due to increased risk of adverse effects 3, 4
• Be aware that the majority of dosing errors and cardiovascular adverse reactions occur when epinephrine is given intravenously or incorrectly dosed 6
• There are no absolute contraindications to epinephrine use in anaphylaxis, even in high-risk patients (elderly with comorbidities, complex congenital heart disease, pulmonary hypertension) 1