Is Epinephrine an Inotrope?
Yes, epinephrine is definitively classified as an inotrope with potent positive inotropic effects mediated through beta-adrenergic receptor stimulation that increases myocardial contractility and cardiac output. 1, 2
Mechanism of Inotropic Action
Epinephrine exerts its inotropic effects through direct myocardial stimulation that increases the strength of ventricular contraction (positive inotropic action), alongside increased heart rate (positive chronotropic action). 2 The drug acts on both alpha and beta-adrenergic receptors, with the beta-1 receptor stimulation specifically responsible for enhanced cardiac contractility. 3, 4
At low doses (<0.3 mcg/kg/min), epinephrine predominantly produces β-adrenergic effects including increased inotropy and decreased systemic vascular resistance, while at higher doses (>0.3 mcg/kg/min), α-adrenergic vasoconstriction effects become more prominent. 1
Clinical Classification and Dosing
Epinephrine is formally classified as an "inoconstrictор"—a medication that provides both inotropic support and vasopressor effects. 4 This distinguishes it from pure inotropes like dobutamine (inodilators) and pure vasopressors like phenylephrine. 4
The European Society of Cardiology recommends epinephrine as an inotropic agent with a recommended infusion rate of 0.05-0.5 μg/kg/min in acute heart failure management. 1 Guidelines explicitly list epinephrine alongside other recognized inotropes with specific dosing recommendations for its inotropic effects. 3, 1
Context-Specific Use
When Epinephrine IS Recommended as an Inotrope:
- Neonatal hypoxic-ischemic encephalopathy with shock: The American Academy of Pediatrics recommends epinephrine as the first-line inotrope (0.05-0.3 μg/kg/min) due to potent inotropic effects and superior outcomes compared to dopamine in this population. 5
- Cardiac arrest resuscitation: Standard dosing of 2-10 mcg/min for advanced cardiac life support. 3
- Septic shock (dose-dependent): Produces linear increases in cardiac index, stroke volume, and oxygen delivery in the 3-18 microgram/min range without affecting systemic vascular resistance or pulmonary artery occlusion pressure. 6
When Epinephrine Should Be AVOIDED Despite Inotropic Properties:
- Cardiogenic shock: The European Society of Cardiology explicitly states that epinephrine is NOT recommended as an inotrope or vasopressor in cardiogenic shock and should be restricted to rescue therapy in cardiac arrest only. 7 This is a critical caveat—while epinephrine IS an inotrope pharmacologically, it should not be used for this indication in cardiogenic shock due to increased myocardial oxygen demand and arrhythmia risk. 3, 7
Important Clinical Caveats
All inotropes, including epinephrine, increase myocardial oxygen demand, ischemic burden, and risk of malignant arrhythmias, necessitating use at the lowest possible doses for the shortest duration. 3 The standard dosage for advanced cardiac life support is 2-10 mcg/min with titration to hemodynamic response, though higher doses may result in vasoconstriction or arrhythmias. 3
Epinephrine displays dose-proportional pharmacokinetics with rapid onset (<5 minutes) and short duration of action (offset within 20 minutes), achieving steady state within 10-15 minutes of continuous infusion. 2 This rapid clearance (effective half-life <5 minutes) requires continuous infusion for sustained inotropic effect. 2