CC Pharm | Epinephrine

Epinephrine is a potent, nonselective adrenergic agonist acting on alpha-1, alpha-2, beta-1, and beta-2 receptors. This high-yield 80/20 summary covers the essential clinical and exam concepts: 1. Expected Pharmacological Action & Mechanism Alpha-1 activation causes arteriolar vasoconstriction. Beta-1 activation induces positive inotropic and chronotropic responses, increasing cardiac workload and coronary vasodilation. Beta-2 activation drives bronchodilation, skeletal muscle vasodilation, and hepatic glycogenolysis. Alpha-2 activation inhibits insulin release and provides negative feedback on norepinephrine. Actions are mediated by cyclic AMP (increased by beta, decreased by alpha). 2. Clinical Indications & Route Optimization Anaphylaxis: Drug of choice. Intramuscular (IM) injection in the anterolateral thigh (vastus lateralis) is preferred because absorption is rapid and complete. Subcutaneous (SQ) absorption is delayed and variable, making it not routinely recommended. Cardiac Arrest: Administer 1 mg IV or IO every 3 to 5 minutes. Do not interrupt CPR to administer. Flush with 0.9% NaCl to promote central entry. Hemodynamic Support: Continuous IV infusion at 0.01 to 2 mcg/kg/min. Low doses (<0.3 mcg/kg/min) favor beta-effects (tachycardia, inotropy, decreased SVR), while higher doses (>0.3 mcg/kg/min) cause alpha-vasoconstriction. Endotracheal (ET): Used only if IV/IO is delayed. Requires higher doses (e.g., 2 to 2.5 mg in adults) and is associated with lower drug levels and survival. 3. Safety, Administration & Nursing Interventions Extravasation Antidote: Extravasation causes severe ischemia and tissue necrosis. Avoid peripheral leg veins in the elderly. Immediately infiltrate the cold, pale area with phentolamine (5 to 10 mg in 10 to 15 mL saline for adults). Incompatibilities: Epinephrine is inactivated in alkaline solutions and is incompatible with sodium bicarbonate. Protect from light; discard if cloudy, pinkish, or brownish. Metabolic Tracking: Monitor for transient hyperkalemia followed by hypokalemia (due to potassium uptake into skeletal muscles), and hyperglycemia (due to insulin inhibition and glycogenolysis). Complications: Watch for severe reactions including stroke, myocardial infarction, ventricular fibrillation/tachycardia, pulmonary edema, and severe hypertension.