Vasopressor · Inotrope · Catecholamine · Bronchodilator
Epinephrine (Adrenalin)
Also called Adrenalin
Watch the explainer
Indications
- Anaphylaxis: IM first; IV infusion if shock persists
- Septic shock: added to norepinephrine, or first with cardiac dysfunction
- Cardiac arrest (AHA; off-label)
- Symptomatic bradycardia after atropine, as a bridge to pacing (off-label)
- Low output after cardiac surgery or in cardiogenic shock (off-label)
- Croup and post-extubation stridor, nebulized (off-label)
- Push-dose boluses for brief hypotension (off-label)
Dosing
Epinephrine drip card and mL/h converterStart: 0.02–0.05 mcg/kg/min (1–4 mcg/min)
| Where | Dose |
|---|---|
| Cardiac arrest | Epinephrine: 1 mg IV/IO every 3–5 min |
| Rhythm control | Epinephrine infusion: 2–10 mcg/min |
| Blood pressure boluses | Epinephrine: 10–20 mcg (1–2 mL of 10 mcg/mL) every 2–5 min |
| Other common pushes | Epinephrine (anaphylaxis): 0.3–0.5 mg IM (1 mg/mL) mid-outer thigh, repeat every 5–15 min |
Mechanism of action
Epinephrine, the adrenal medullary hormone, directly activates α1, α2, β1 and β2 receptors. β receptors couple to Gs: cAMP and protein kinase A strengthen and speed the heartbeat and relax bronchial and arteriolar smooth muscle. α1 receptors couple to Gq: IP3 releases calcium and constricts vessels. β receptors respond at lower concentrations, so β effects dominate at low doses and α1 vasoconstriction at high doses.
Pharmacology
- Cardiovascular, low dose (about 0.01–0.05 mcg/kg/min): β1 raises heart rate, contractility and output; β2 dilates muscle beds, so diastolic pressure may fall
- Cardiovascular, higher doses: α1 constriction dominates, raising SVR, MAP, O₂ demand and arrhythmia risk
- Cardiovascular, in arrest: α1 raises aortic diastolic and coronary perfusion pressure
- Respiratory: β2 bronchodilation and less mast cell mediator release; α1 shrinks mucosal edema
- Metabolic: glycogenolysis and less insulin release raise glucose; β2-driven aerobic glycolysis raises lactate without hypoperfusion; K⁺ shifts into cells
Pharmacokinetics
| Onset | IV about 1 min; IM thigh within minutes (higher peaks than SC or arm) |
|---|---|
| Peak | Steady state 10–15 min after an infusion change (label) |
| Duration | Minutes after stopping IV; IM doses may need repeating every 5–15 min |
| Half-life | Under 5 min (label) |
| Metabolism | Uptake, then MAO and COMT to inactive VMA; liver 32%, kidney 25%, muscle 20%, gut 12% of removal (label) |
| Elimination | Urine, as metabolites; little unchanged |
| Routes | IV, IO, IM, SC, nebulized; endotracheal absorption is unreliable |
Chemistry
- Natural catecholamine: N-methyl norepinephrine (catechol ring, β-hydroxyl, N-methyl); the methyl adds β2 potency
- Given as the l-(R) isomer; racemic epinephrine for inhalation is half d-isomer, which is far weaker
- Amine pKa about 8.6 (PubChem): ionized and water-soluble at pH 7.4
- 1 mg/mL vials and 0.1 mg/mL syringes (formerly 1:1,000 and 1:10,000) with sodium metabisulfite, pH 2.2–5.0
- Light, air and alkali oxidize it (pink adrenochrome, then brown): protect from light, dilute in dextrose (label), discard if discolored, never mix with bicarbonate
Adverse effects and cautions
In the one-pagers
- Vasopressors and InotropesReceptors and effects: Epinephrine: β1, β2, α1: ↑↑ / ↑↑ / ↑ (↓ at low dose)
- ACLS Algorithms in BriefCardiac arrest: two tracks: First move: Shock, resume CPR at once: CPR and epinephrine ASAP
- Pediatric Assessment and EmergenciesCroup, epiglottitis, bronchiolitis: Croup, paramedic (NASEMSO): dexamethasone 0.6 mg/kg (max 16 mg); nebulized epinephrine 5 mg (5 mL of 1 mg/mL), may repeat in 20 min, per protocol
- Shock Types at a GlanceFindings and first treatments: Anaphylactic: Hives, angioedema, wheeze or stridor: IM epinephrine first; IV fluids; epinephrine infusion if refractory
- Newborn Care and ResuscitationCompressions, epinephrine and volume: HR below 60 after 60 s of compressions: epinephrine every 3 to 5 min
- After Cardiac SurgeryArrest after cardiac surgery (CSU-ALS): No routine epinephrine or vasopressin; small doses only if an experienced clinician directs
Practice Vasopressors and Inotropes questions free132 exam-style questions with rationales on the topic where Epinephrine comes up most. No account or download needed.
In the algorithms
- New Hypotension
- Traumatic Cardiac Arrest
- Field Delivery and Newborn Care
- Adult Cardiac Arrest
- Bradycardia With a Pulse
- Arrest After Cardiac Surgery
- VT Storm
- Massive Hemoptysis
- Sepsis: Hour-1 Bundle
- Anaphylaxis
- Massive Pulmonary Embolism
- Local Anesthetic Toxicity
- Accidental Hypothermia
- Pediatric Cardiac Arrest (PALS)
- Pediatric Bradycardia With a Pulse
Other vasopressor drugs
Practice free in your browser3,800+ exam-style questions with rationales. No account, no ads. Also free on the App Store and Google Play.
Sources
- FDA label: Adrenalin (2022)
- FDA label: epinephrine 0.1 mg/mL syringe (2025)
- PubChem: epinephrine
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow the order, the label and your institution's protocols.