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# Norepinephrine
## Overview
Norepinephrine is a potent catecholamine with primary alpha-1 agonist activity (vasoconstriction) and moderate beta-1 agonist activity (inotropic effect). It is the first-line vasopressor for septic shock.
## Primary Indications
* Acute hypotensive states (e.g., septic shock, cardiogenic shock).
* Hemodynamic support during cardiac arrest (refractory).
## Adult Dosing
* **Initial:** 0.05–0.1 mcg/kg/min via continuous IV infusion.
* **Titration:** Titrate to achieve target Mean Arterial Pressure (MAP), typically 65 mmHg. Usual maintenance range is 0.01–3 mcg/kg/min.
* **Max Dose:** No absolute maximum; doses >3–5 mcg/kg/min are common in refractory shock but carry significant risk of ischemia.
## Pediatric Dosing
* **Initial:** 0.05–0.1 mcg/kg/min via continuous IV infusion.
* **Titration:** Titrate by 0.05–0.1 mcg/kg/min every 5–10 minutes to reach target MAP based on age-appropriate thresholds. Range: 0.01–2 mcg/kg/min.
* *Note: Always verify concentration and infusion rates per institutional PALS/pediatric ICU protocols.*
## Dose Adjustments
* **Hepatic/Renal:** No routine dose adjustments required.
* **Weaning:** Avoid abrupt discontinuation to prevent rebound hypotension. Taper gradually as hemodynamic stability improves.
## Contraindications
* Hypersensitivity to norepinephrine.
* Hypotension caused by uncorrected hypovolemia (volume resuscitation must be priority).
* Use as sole agent in profound cardiogenic shock (may increase afterload and myocardial oxygen demand).
## Adverse Effects
* **Cardiovascular:** Arrhythmias (bradycardia or tachycardia), hypertension, myocardial ischemia.
* **Localized:** Extravasation can lead to severe tissue necrosis and gangrene.
* **Peripheral:** Digital or visceral ischemia (due to intense vasoconstriction).
## Key Drug Interactions
* **MAOIs/Tricyclic Antidepressants:** May cause severe, prolonged hypertension.
* **Beta-Blockers:** May antagonize cardiac effects and lead to unopposed alpha-mediated vasoconstriction (severe hypertension).
* **Halogenated Anesthetics:** May sensitize the myocardium to arrhythmogenic effects.
## Monitoring
* **Continuous:** ECG monitoring for arrhythmias and invasive arterial blood pressure (preferred).
* **Physical:** Monitor IV site frequently for signs of infiltration/extravasation. Assess perfusion in distal extremities.
* **Laboratory:** Lactate levels, venous oxygen saturation (ScvO2), and urine output to assess organ perfusion.
## Clinical Pearls
* **Extravasation Management:** If extravasation occurs, stop the infusion immediately and infiltrate the area with **phentolamine** (alpha-adrenergic antagonist) to prevent necrosis.
* **Administration:** Must be administered through a large-bore peripheral vein or, preferably, a central venous catheter. Do not administer in the same line as alkaline drugs (e.g., sodium bicarbonate).
* **Compatibility:** Highly vasoactive; dedicated line is strongly recommended.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical practice varies by institution; always consult local hospital protocols, guidelines, and verified package inserts before prescribing or administering medication.
