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# Norepinephrine
## Overview
Norepinephrine (levarterenol) is a potent sympathomimetic amine with predominantly alpha-1 agonist activity causing peripheral vasoconstriction, and beta-1 agonist activity causing positive inotropic and chronotropic effects. It is the first-line vasopressor for septic and distributive shock.
## Primary Indications
* Acute hypotensive states (e.g., septic, cardiogenic, or neurogenic shock).
* Cardiac arrest (less common than epinephrine).
## Adult Dosing
* **Initial:** 0.05–0.1 mcg/kg/min or 2–5 mcg/min continuous IV infusion.
* **Titration:** Titrate in increments of 0.05–0.1 mcg/kg/min every 3–5 minutes to achieve target mean arterial pressure (MAP) (usually ≥65 mmHg).
* **Maintenance:** Typical range 0.01–3 mcg/kg/min. High doses (>1 mcg/kg/min) may cause peripheral ischemia.
* **Maximum:** No formal upper limit, but typically capped based on local protocol and clinical goal (often 1–2 mcg/kg/min before adding a second agent like vasopressin).
## Pediatric Dosing
* **Initial:** 0.05–0.1 mcg/kg/min continuous IV infusion.
* **Titration:** Titrate to clinical effect; usual effective range 0.05–0.5 mcg/kg/min.
* **Maximum:** Up to 1–2 mcg/kg/min in refractory shock.
* *Note: Dosing depends heavily on the specific pediatric resuscitation unit protocol.*
## Dose Adjustments
* **Renal/Hepatic:** No formal dose adjustments; however, use with caution and monitor for persistent hypoperfusion.
* **Geriatric:** Initiate at the lower end of the dosing range due to cardiovascular sensitivity.
## Contraindications
* Hypersensitivity to norepinephrine or sulfite-containing products.
* Hypotension due to uncorrected hypovolemia (volume resuscitation must be attempted first).
## Adverse Effects
* **Cardiovascular:** Hypertension, tachyarrhythmias, bradycardia (reflex), myocardial ischemia.
* **Local:** Extravasation can lead to skin necrosis and sloughing.
* **Metabolic:** Hyperglycemia, lactic acidosis (secondary to peripheral ischemia).
## Key Drug Interactions
* **MAO Inhibitors/Tricyclic Antidepressants:** May cause severe, prolonged hypertensive crisis.
* **Beta-blockers:** May cause excessive alpha-adrenergic effects and peripheral vasoconstriction.
* **General Anesthetics (e.g., halothane, cyclopropane):** May increase myocardial irritability and risk of ventricular arrhythmias.
## Monitoring
* **Hemodynamics:** Continuous blood pressure monitoring (preferably via arterial line).
* **Perfusion:** Mental status, urine output, serum lactate, and peripheral temperature/color.
* **Infusion Site:** Monitor for infiltration every hour; utilize central venous access whenever feasible.
## Clinical Pearls
* **Extravasation Management:** If extravasation occurs, stop the infusion immediately. Administer phentolamine (5–10 mg in 10 mL of 0.9% NaCl) via subcutaneous injection into the affected area.
* **Compatibility:** Must be administered via a dedicated IV line; do not Y-site with other medications unless verified compatible.
* **Stabilization:** Norepinephrine is the vasopressor of choice for septic shock according to the Surviving Sepsis Campaign guidelines.
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*Disclaimer: This information is for educational purposes only. Clinical practice varies by institution. Always verify current, hospital-specific protocols and the manufacturer’s prescribing information before administration.*
