Epinephrine is given to patients with allergic reactions/anaphylaxis to stimulate which receptors?

• A. Dopaminergic and Beta 1
• B. Alpha 2 and Beta 1
• C. Alpha 1 and Beta 1
• D. Alpha 1 and Beta 2

Answer: (D)

In anaphylaxis the aim is to rapidly reverse airway obstruction and improve blood pressure. Epinephrine achieves this by activating two key receptor types: alpha-1 and beta-2. Alpha-1 stimulation causes vasoconstriction of peripheral and mucosal vessels, which reduces swelling, raises systemic vascular resistance, and helps restore blood pressure. Beta-2 stimulation relaxes bronchial smooth muscle, producing bronchodilation to relieve wheeze and airway narrowing, and also helps stabilize mast cells to limit further mediator release. The combination of these effects addresses both the airway compromise and the vascular collapse that can occur during an allergic reaction. While beta-1 effects (increasing heart rate and contractility) also play a supportive role in maintaining perfusion, the essential therapeutic actions in anaphylaxis come from alpha-1 and beta-2 stimulation.