Norepinephrine
Norepinephrine Bitartrate — Potent Alpha-1 & Beta-1 Inotrope / Vasopressor
🧬 Mechanism of Action & Target Pathway
Alpha-1 Vascular Smooth Muscle & Beta-1 Cardiomyocyte Agonism
- Binds vascular alpha-1 adrenergic receptors, inducing intense arterial and venous vasoconstriction.
- Increases Systemic Vascular Resistance (SVR) and Mean Arterial Pressure (MAP).
- Stimulates cardiac beta-1 adrenergic receptors, increasing myocardial contractility and stroke volume.
- Minimal beta-2 receptor activation, preventing unwanted peripheral vasodilation.
Pharmacokinetics & Pharmacodynamics (PK/PD) — Norepinephrine
receptor occupancy⚖️ ICU Clinical Reasoning
Why I Choose It (Indications & Strengths)
- ✓First-line recommended vasopressor in Surviving Sepsis Campaign guidelines for Septic Shock.
- ✓Increases MAP primarily via SVR elevation while preserving or increasing cardiac output.
- ✓Lower arrhythmia risk compared to Dopamine.
Why I Don't (Limitations & Gaps)
- ✕Extravasation causes severe local tissue ischemic necrosis.
- ✕Excessive vasoconstriction in hypovolemia causes visceral and digital ischemia.
- ✕Increases myocardial oxygen demand.
💉 Dosing & Administration Protocols
Septic shock: titrate norepinephrine promptly to the perfusion/MAP target (SSC uses an initial MAP target around 65 mmHg for most adults), using the institution’s standardized concentration and weight-based or non-weight-based protocol. Do not equate 0.02–0.05 mcg/kg/min with a fixed 2–5 mcg/min across body weights. Current U.S. norepinephrine labeling for acute hypotension starts 8–12 mcg/min and lists a typical maintenance dose of 2–4 mcg/min; ICU sepsis protocols commonly use different weight-based starting schemes. There is no universal evidence-based maximum in refractory shock.
Renal Function Dosing
| CrCl Range | Dose Adjustment |
|---|---|
| Any CrCl | No renal adjustment required; titrate to target MAP. |
Dialytic Clearance (HD / CRRT)
🩺 Organ Failure Considerations
Use to restore an appropriate perfusion pressure; do not claim a predictable increase in GFR. Renal response depends on baseline perfusion, congestion, autoregulation and overall shock resuscitation.
Titrate to hemodynamic effect; no universal hepatic dose adjustment is used in shock, but critical illness can alter response.
⚠️ Toxicity & Safety Warnings
Major Warnings
- 🚨Peripheral extravasation causes severe ischemic tissue necrosis.
- 🚨Severe organ hypoperfusion if given without adequate volume resuscitation in hypovolemia.
- 🚨Arrhythmias and myocardial ischemia.
🔄 Bedside Drug Interactions
| Interacting Drug | Mechanism | Clinical Consequence | Mandatory ICU Action |
|---|---|---|---|
| MAO Inhibitors / Tricyclic Antidepressants | Inhibition of catecholamine breakdown | Severe hypertensive crisis | Titrate norepinephrine extremely cautiously at low initial doses. |
📊 Monitoring & TDM Protocols
Required Monitoring Parameters
- ▪ Continuous arterial blood pressure (arterial line preferred)
- ▪ Heart rate and ECG rhythm
- ▪ Perfusion markers (lactate, urine output, ScvO2)
- ▪ IV site for extravasation
Evidence Status
CurrentLast Medically Reviewed
2026-08-28
Evidence Checked Through
2026-08-28
📚 Evidence Traceability & Guideline Citations
"Surviving Sepsis Campaign 2026 recommends norepinephrine as the first-line vasopressor for adults with septic shock."
🩺 Bedside Patient Scenarios
Vasodilatory Septic Shock
Scenario: A 70-year-old with urosepsis has persistent hypotension and signs of hypoperfusion after initial individualized crystalloid resuscitation.
Rationale: Norepinephrine is the SSC 2026 first-line vasopressor for septic shock; response should be judged by overall perfusion rather than assuming a guaranteed renal effect.
🎯 Exam Traps & Board Misconceptions
In the SOAP II trial, dopamine caused significantly more arrhythmias (20.7% vs 12.4%, p<0.001) without mortality benefit in septic shock, supporting norepinephrine as first-line.
🫀 Physiology & Hemodynamics
Norepinephrine
drugMechanism
Potent α1 agonism → arterial/venous vasoconstriction; modest β1 → increased contractility. Minimal β2 effect.
Continue Learning
Shock: Foundational Critical Care Framework
Cellular dysoxia, DO2/VO2 physiology, the 4 shock phenotypes, dynamic fluid responsiveness (PLR/PPV) vs fluid tolerance (VExUS), and vasoactive pharmacology.
Septic Shock
The subset of sepsis with profound circulatory and cellular/metabolic abnormality — clinically identified by a vasopressor requirement to maintain MAP ≥ 65 mmHg plus lactate > 2 mmol/L despite adequate fluid resuscitation.
Septic Shock Resuscitation
2026 SSC-aligned fluids, early norepinephrine, dynamic reassessment, and perfusion endpoints
Severe Diabetic Ketoacidosis Resuscitation
Fluid resuscitation, potassium kinetics, insulin therapy, and safe transition
Acute Hypotension & Undifferentiated Shock
Rapid bedside hemodynamic categorization: confirming MAP < 65 mmHg, assessing peripheral perfusion, POCUS cardiac/IVC profiling, and differentiating hypovolemic, distributive, cardiogenic, and obstructive etiologies.
Refractory Shock Despite High-Dose Vasopressors
Advanced multimodal hemodynamic rescue: second-line vasopressors (vasopressin, angiotensin II), inotropic augmentation, stress-dose steroids, metabolic correction, and mechanical circulatory support evaluation.