MOA of adrenaline
Adrenaline acts on both alpha- and beta-adrenergic receptors.
Through its action on alpha-adrenergic receptors, adrenaline lessens the vasodilation and increased vascular permeability that occurs during an anaphylactic reaction that can lead to loss of intravascular fluid volume and hypotension. Through its action on beta-adrenergic receptors, adrenaline causes bronchial smooth muscle relaxation that helps alleviate bronchospasm, wheezing, and dyspnoea that may occur during anaphylaxis.15,20 Beta-adrenergic action also works on the heart to enhance coronary blood flow and increase cardiac output to increase blood pressure.
Two mechanisms have been proposed for the cardiac effects, which counteract the vasoconstrictor effects of adrenaline on the coronary arteries:39
- increased duration of diastole compared to systole
- vasodilator effect due to increased myocardial contractility
- 15 - Simons FER et al. J Allergy Clin Immunol 2011; 127(3):587-93.
- 20 - Kemp SF et al. World Allergy Org J 2008;1(7):S18-S26.
- 39 - Kemp SF et al. Allergy 2008;63:1061-70.