What is the difference between epinephrine (adrenaline) and dopamine in a clinical setting for treating conditions like cardiac arrest and hypotension?

Epinephrine vs Dopamine in Clinical Practice

Direct Recommendation

For septic shock, norepinephrine should be the first-line vasopressor, but when choosing between dopamine and epinephrine specifically, dopamine carries higher mortality risk in cardiogenic shock and increased arrhythmia rates across all shock types, making epinephrine the preferred alternative when norepinephrine is unavailable or inadequate. 1, 2

Context-Specific Applications

Septic Shock Management

Norepinephrine is superior to both dopamine and epinephrine as first-line therapy for fluid-refractory septic shock. 1, 3 The 2012 Surviving Sepsis Campaign guidelines, based on meta-analysis of 2,043 patients, demonstrated that dopamine increased mortality (RR 1.10,95% CI 1.01-1.20) and arrhythmias (RR 2.34,95% CI 1.46-3.77) compared to norepinephrine. 1

When norepinephrine is unavailable or as second-line therapy:

• Epinephrine should be chosen over dopamine 1
• Four randomized trials (n=540) showed no mortality difference between norepinephrine and epinephrine (RR 0.96,95% CI 0.77-1.21) 1
• Dopamine demonstrated 24.1% arrhythmia rate versus 12.4% with norepinephrine (p<0.001) 2

Critical caveat: Epinephrine increases aerobic lactate production through β2-adrenergic stimulation of skeletal muscle, making lactate clearance unreliable for monitoring resuscitation adequacy. 1 Norepinephrine should be preferred when available specifically to avoid this confounding effect. 1

Pediatric Septic Shock

In children with fluid-refractory hypotensive cold septic shock, epinephrine is more effective than dopamine as first-line vasoactive therapy. 4 A 2016 randomized controlled trial (n=60) demonstrated:

• Resolution of shock within 1 hour: 41% with epinephrine vs 13% with dopamine (OR 4.8,95% CI 1.3-17.2, p=0.019) 4
• Lower Sequential Organ Function Assessment scores on day 3 (8 vs 12, p=0.05) 4
• More organ failure-free days (24 vs 20 days, p=0.022) 4

Age-specific consideration: Infants <6 months may show reduced responsiveness to dopamine due to incomplete sympathetic innervation and reduced norepinephrine stores in sympathetic vesicles. 1 This makes epinephrine or norepinephrine more reliable in neonates and young infants. 1

Cardiogenic Shock

Dopamine is contraindicated as first-line therapy in cardiogenic shock due to increased mortality. 2 The landmark 2010 NEJM trial showed dopamine increased 28-day mortality in the cardiogenic shock subgroup (280 patients) compared to norepinephrine (p=0.03 in Kaplan-Meier analysis). 2

For cardiogenic shock management:

• Norepinephrine remains first-line to maintain MAP ≥65 mmHg 3
• Dobutamine (2.5-10 μg/kg/min) should be added for low cardiac output states 3
• Epinephrine may be considered as salvage therapy when combined inotrope/vasopressor drugs fail 1

Resource-Limited Settings

In resource-limited settings without access to norepinephrine, either dopamine or epinephrine can be used for fluid-refractory shock, but epinephrine is preferred due to dopamine's inferior outcomes. 1

Practical administration considerations:

• Both can be given via peripheral IV or intraosseous route when central access unavailable 1
• Dilute dopamine (250 mg) or epinephrine (5-10 mg) in 500 mL crystalloid for drop regulator administration when infusion pumps unavailable 1
• Monitor infusion site every 15 minutes for extravasation—both agents cause severe tissue necrosis 1
• Combined dopamine plus epinephrine is discouraged 1

Post-Cardiac Arrest Shock

Norepinephrine is strongly preferred over epinephrine for post-resuscitation shock following out-of-hospital cardiac arrest. 5 A 2022 multicenter study (n=766) demonstrated:

• All-cause hospital mortality: OR 2.6 (95% CI 1.4-4.7, p=0.002) favoring norepinephrine 5
• Cardiovascular-specific mortality: aOR 5.5 (95% CI 3.0-10.3, p<0.001) favoring norepinephrine 5
• Worse neurological outcomes (CPC 3-5) with epinephrine 5

Important distinction: During active cardiac arrest resuscitation, epinephrine remains the recommended drug via bolus administration, not continuous infusion. 6 The above applies only to post-resuscitation shock management.

Anaphylaxis

Intramuscular epinephrine is the definitive first-line treatment for anaphylaxis; dopamine serves only as a secondary vasopressor for refractory hypotension. 1

Algorithm for anaphylaxis-related hypotension:

1. IM epinephrine 0.01 mg/kg (max 0.3-0.5 mg) every 5 minutes 1
2. Aggressive fluid resuscitation: 5-10 mL/kg in first 5 minutes (adults), up to 30 mL/kg in first hour (children) 1
3. If hypotension persists despite epinephrine and fluids, start dopamine infusion 2-20 μg/kg/min titrated to maintain systolic BP >90 mmHg 1

Dopamine is preferred in this specific context because it maintains renal and splanchnic blood flow while increasing blood pressure. 1

Pharmacologic Distinctions

Dopamine Mechanism

• Dose-dependent receptor activity: dopaminergic (2-5 μg/kg/min), β-adrenergic (5-10 μg/kg/min), α-adrenergic (>10 μg/kg/min) 1
• Releases norepinephrine from sympathetic vesicles (indirect action) 1
• Increases MAP and cardiac output primarily through increased stroke volume and heart rate 1
• May suppress anterior pituitary hormones (prolactin, thyrotropin) with potential immunosuppressive effects 1

Epinephrine Mechanism

• Direct α and β-adrenergic agonist 1
• At low doses (<0.3 μg/kg/min): predominant β2-vasodilation in skeletal muscle, may reduce splanchnic perfusion 1
• Potent inotropic and chronotropic effects 1
• Stimulates gluconeogenesis and Cori cycle, elevating lactate independent of tissue hypoperfusion 1

Critical Safety Considerations

Monitor for arrhythmias more vigilantly with dopamine—the incidence is approximately double that of norepinephrine or epinephrine. 1, 2

Blood pressure monitoring requirements:

• Measure every 5-15 minutes during infusion 1
• Use appropriately sized cuffs in children to ensure accuracy 1
• Invasive monitoring preferred but non-invasive acceptable 1

Extravasation prevention:

• Central venous access strongly preferred for both agents 1
• If peripheral access necessary, use large-bore vein 1
• Inspect site frequently—both cause severe skin necrosis 1