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Scroll down or Click Here forDuring anaphylaxis, epinephrine has potent symptom reversing alpha-1 adrenergic vasoconstrictor effects on the precapillary sphincters and small arterioles in most body systems, decreasing mucosal edema and increasing blood pressure (Figure 1). The combined effect of its vasoconstriction properties is to relieve upper airway obstruction and prevent and relieve shock. Epinephrine also has beta-1 adrenergic effects, which increase the rate and force of cardiac contractions, as well as beta-2 adrenergic effects, which increase bronchodilation and decrease release of histamine, tryptase, and other inflammation mediators from mast cells and basophils (Figure 1).2-4
Clinicians often utilize other medications to manage the residual symptoms after an anaphylactic reaction. These include H1-antihistamines (eg, diphenhydramine), corticosteroids (eg, methylprednisolone), and β2-adrenergic agonists (eg, albuterol). However, it is important to note that these medications are not approved for the management of anaphylaxis; therefore, they should not take the place of epinephrine as the primary treatment of this disorder1,3.
NIH-NIAID Food Allergy Guidelines recommend that epinephrine is the first-line treatment in all cases of anaphylaxis. All other drugs have a delayed onset of action. When there is suboptimal response to the initial dose of epinephrine, or if symptoms progress, repeat epinephrine dosing remains first-line therapy over adjunctive treatments1,3.
