vasopressor

Epinephrine

Adrenalin / EpiPen / Auvi-Q

Route: IV · IO · IM · inhaled (nebulized racemic epinephrine) · ET (cardiac arrest — least preferred)
Onset: Immediate (IV); 5–10 minutes (IM)
Duration: 5–10 minutes (IV bolus)

Mechanism of action

Endogenous catecholamine. Activates alpha-1 (vasoconstriction), beta-1 (increased HR and contractility), and beta-2 (bronchodilation) receptors. Dose-dependent effects: low doses primarily beta; high doses alpha-dominant.

Dosing

Adult: Cardiac arrest: 1 mg IV q3–5 min. Anaphylaxis: 0.3–0.5 mg IM (1:1000 concentration). Vasopressor: 0.01–0.5 mcg/kg/min IV infusion
Pediatric: Cardiac arrest: 0.01 mg/kg (0.1 mL/kg of 0.1 mg/mL) IV/IO q3–5 min. Anaphylaxis: 0.01 mg/kg IM (max 0.5 mg)
Neonatal: Cardiac arrest: 0.01–0.03 mg/kg IV/ET

Indications

Cardiac arrest (first-line vasopressor in ACLS)
Anaphylaxis (first-line)
Severe bronchospasm (racemic epinephrine for croup)
Septic shock (adjunct vasopressor)
Bradycardia (refractory to atropine)

Contraindications

Anaphylaxis: no absolute contraindication
Narrow-angle glaucoma
Cardiac arrhythmias (use with caution)
Hypertension / pheochromocytoma

Side effects

Tachycardia and arrhythmias
Hypertension
Myocardial ischemia
Anxiety/tremor
Pallor
Hypokalemia
Hyperglycemia

Monitoring parameters

Continuous cardiac monitoring (ECG)
Blood pressure (arterial line in ICU)
Urine output
SpO2
Signs of ischemia

Drug interactions

Beta-blockers (antagonize beta effects; alpha effects unopposed → severe hypertension)
MAOIs (severe hypertensive crisis)
Halothane anesthesia (sensitizes myocardium to arrhythmias)
Tricyclic antidepressants (potentiate adrenergic effects)

NBRC high-yield

First-line for cardiac arrest (1 mg IV q3–5 min) AND anaphylaxis
Anaphylaxis: 1:1000 IM preferred; 1:10,000 IV if in cardiac arrest
Racemic epinephrine SVN for croup and post-extubation stridor
Rebound croup: observe ≥3 hours after racemic epinephrine
Alpha + beta + beta-2 effects: vasoconstriction + inotrope + bronchodilator

Clinical pearls

In anaphylaxis: ALWAYS use 1:1000 concentration for IM; 1:10,000 for IV
Anaphylaxis: IM injection preferred over SC (faster absorption)
Racemic epinephrine (2.25% solution SVN) for croup — reduces subglottic edema via alpha-vasoconstriction
Rebound (return of croup symptoms) can occur 2–3 hours after racemic epinephrine — must observe for 3+ hours
In cardiac arrest: first dose given 3–5 min after first shock (if shockable rhythm)
High-dose epinephrine does NOT improve outcomes in cardiac arrest

Mnemonic

EPI = Every Pulseless Individual (cardiac arrest drug #1), also Anaphylaxis #1

All Drugs

Dosing

Adult

Cardiac arrest: 1 mg IV q3–5 min. Anaphylaxis: 0.3–0.5 mg IM (1:1000 concentration). Vasopressor: 0.01–0.5 mcg/kg/min IV infusion

Pediatric

Cardiac arrest: 0.01 mg/kg (0.1 mL/kg of 0.1 mg/mL) IV/IO q3–5 min. Anaphylaxis: 0.01 mg/kg IM (max 0.5 mg)

Neonatal

Cardiac arrest: 0.01–0.03 mg/kg IV/ET

NBRC high-yield

First-line for cardiac arrest (1 mg IV q3–5 min) AND anaphylaxis

Anaphylaxis: 1:1000 IM preferred; 1:10,000 IV if in cardiac arrest

Racemic epinephrine SVN for croup and post-extubation stridor

Rebound croup: observe ≥3 hours after racemic epinephrine

Alpha + beta + beta-2 effects: vasoconstriction + inotrope + bronchodilator

Clinical pearls

In anaphylaxis: ALWAYS use 1:1000 concentration for IM; 1:10,000 for IV

Anaphylaxis: IM injection preferred over SC (faster absorption)

Racemic epinephrine (2.25% solution SVN) for croup — reduces subglottic edema via alpha-vasoconstriction

Rebound (return of croup symptoms) can occur 2–3 hours after racemic epinephrine — must observe for 3+ hours

In cardiac arrest: first dose given 3–5 min after first shock (if shockable rhythm)

High-dose epinephrine does NOT improve outcomes in cardiac arrest