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Adrenaline in Emergency Medicine: Uses, Doses, and Routes

Adrenaline (Epinephrine) is a potent, life-saving sympathomimetic drug that acts on both α and β adrenergic receptors, producing widespread cardiovascular, respiratory, and metabolic effects. Its diverse therapeutic applications can be easily remembered with the mnemonic “ABC-SHOT”, which stands for Anaphylaxis, Bronchial Asthma, Cardiac Arrest, Shock, Hemostasis, Ocular/Nasal Use, and Topical Use. In Anaphylaxis, adrenaline is the drug of choice because of its rapid and life-saving effects. It reverses bronchospasm, hypotension, and laryngeal edema through β₂-mediated bronchodilation, α₁-mediated vasoconstriction, and β₁-induced enhancement of cardiac output. The recommended dose is 0.3–0.5 mg intramuscularly (IM) using a 1:1000 solution (1 mg/mL), administered in the anterolateral thigh (vastus lateralis), and can be repeated every 5–15 minutes as required. In Bronchial Asthma, adrenaline is used in acute severe attacks or status asthmaticus, especially when β₂ agonists fail to provide adequate relief. It acts by stimulating β₂ receptors to produce rapid bronchodilation and relieve airway obstruction. The dose is 0.3–0.5 mg subcutaneously (SC) or IM, prepared as a 1:1000 solution (1 mg/mL). In Cardiac Arrest or during Resuscitation, adrenaline is an essential drug in advanced cardiac life support (ACLS) protocols. It increases myocardial contractility, heart rate, and peripheral perfusion via β₁ and α₁ stimulation. The recommended dose is 1 mg intravenously (IV) every 3–5 minutes during CPR, using a 1:10,000 solution (0.1 mg/mL), and can also be administered intraosseously. In cases of Shock, particularly anaphylactic or septic shock, adrenaline is used when hypotension persists despite adequate fluid resuscitation. It maintains blood pressure and cardiac output through α₁-mediated vasoconstriction and β₁-induced inotropic effects. The infusion is given as 1–4 µg/min intravenously, prepared by diluting 1 mg adrenaline in 100 mL saline (10 µg/mL) and titrated to the desired effect. For Hemostasis or as an adjunct to local anesthetics, adrenaline is combined with agents such as lignocaine in a 1:200,000 concentration (5 µg/mL). It reduces bleeding and prolongs the duration of anesthesia by constricting local blood vessels through α₁ receptor stimulation. In Ocular and Nasal applications, adrenaline is used as a 0.1–0.25% ophthalmic solution for topical administration. It decreases intraocular pressure in glaucoma by reducing aqueous humor production and facilitates nasal decongestion via α₁-mediated vasoconstriction. In Topical Use, such as for minor bleeding or epistaxis, adrenaline is applied locally as a 1:10,000 to 1:20,000 solution (0.1–0.05 mg/mL) on a cotton pledget. This induces vasoconstriction, effectively controlling surface bleeding during ENT or dental procedures. In summary, adrenaline is a multifunctional emergency drug with critical roles in managing acute life-threatening conditions such as anaphylaxis, cardiac arrest, and circulatory shock. It also serves important local and supportive functions in surgery and ophthalmology due to its powerful vasoconstrictor and bronchodilatory properties. Note: The IM route is preferred in anaphylaxis because it provides rapid and safe absorption, whereas IV use is reserved for cardiac arrest or profound shock under close medical supervision. Injections into fingers, toes, ears, or the nose should be avoided due to the risk of severe vasoconstriction and tissue necrosis. Correct dilution and dosing must always be verified before use, and continuous ECG and blood pressure monitoring are essential during intravenous or infusion administration.