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# Norepinephrine
## Overview
Norepinephrine is a potent catecholamine that acts primarily as an alpha-1 adrenergic agonist with moderate beta-1 agonist activity. It causes intense peripheral vasoconstriction and positive inotropic effects, with minimal chronotropic effect compared to other sympathomimetics.
## Primary Indications
* First-line vasopressor for septic shock.
* Hypotension refractory to fluid resuscitation or in neurogenic/cardiogenic shock.
## Adult Dosing
* **Initial:** 0.05 to 0.1 mcg/kg/min or 2 to 4 mcg/min IV continuous infusion.
* **Titration:** Titrate to achieve target Mean Arterial Pressure (MAP) (usually ≥65 mmHg).
* **Maintenance:** 0.01 to 3 mcg/kg/min.
* **Maximum:** Theoretically unlimited based on patient response, but high doses (>1 mcg/kg/min) correlate with poor outcomes; consider adding a second agent (e.g., vasopressin) before escalating indefinitely.
## Pediatric Dosing
* **Initial:** 0.05 to 0.1 mcg/kg/min IV continuous infusion.
* **Titration:** Titrate by 0.05 mcg/kg/min every 5–10 minutes to maintain age-appropriate blood pressure.
* **Maximum:** 2 mcg/kg/min.
* *Note: Always verify local hospital infusion protocols for standardized concentration guidelines.*
## Dose Adjustments
* **Renal/Hepatic:** No specific dose adjustments established; use with caution.
* **Volume Status:** Efficacy is significantly reduced in hypovolemic states. Correct hypovolemia prior to or concurrent with initiation.
## Contraindications
* Hypersensitivity to norepinephrine or sulfites.
* Thrombosis (mesenteric or peripheral vascular) - *relative contraindication; use with extreme caution.*
## Adverse Effects
* **Cardiovascular:** Hypertension, bradycardia (reflex), arrhythmias, myocardial ischemia.
* **Local/Peripheral:** Extravasation can lead to tissue necrosis/sloughing.
* **General:** Peripheral ischemia (fingers, toes, gut), hyperglycemia.
## Key Drug Interactions
* **MAO Inhibitors / TCAs:** May cause severe, prolonged hypertensive crisis.
* **Beta-blockers:** May result in unopposed alpha-1 stimulation (severe hypertensive response).
* **Halogenated Anesthetics:** Increased risk of ventricular arrhythmias.
## Monitoring
* **Continuous:** Real-time arterial blood pressure monitoring (preferred).
* **Clinical:** Heart rate, rhythm, peripheries (capillary refill, temperature), perfusion markers (lactate, urine output).
* **Site:** Inspect IV site frequently for signs of extravasation. If extravasation occurs, administer phentolamine locally.
## Clinical Pearls
* **Central Line Required:** Due to intense vasoconstriction and tissue necrosis risk, administer via a large-bore central venous catheter whenever possible. If used peripherally, utilize a large vein (proximal/antecubital), keep the concentration low, and limit duration.
* **Weaning:** Norepinephrine has a short half-life; wean gradually to avoid rapid hemodynamic collapse.
* **Compatibility:** Highly acidic; check compatibility before Y-site administration.
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**Disclaimer:** This information is for educational purposes only. Drug dosing, local guidelines, and clinical indications may vary. Always verify specific dosing, compatibilities, and administration protocols against current institutional policies and official prescribing information (e.g., Rx package inserts or Lexicomp) before clinical use.
