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# Norepinephrine (Noradrenaline)
## Overview
Norepinephrine is a potent catecholamine with primary alpha-1 adrenergic activity (vasoconstriction) and secondary beta-1 adrenergic activity (inotropy). It is the vasopressor of choice for vasodilatory shock.
## Primary Indications
* Acute hypotensive states (e.g., septic, cardiogenic, or distributive shock).
* Adjunct in cardiac arrest (less common).
## Adult Dosing
* **Initial:** 0.01 to 0.05 mcg/kg/min continuous IV infusion.
* **Titration:** Titrate in increments of 0.01 to 0.05 mcg/kg/min every 2–5 minutes to achieve target Mean Arterial Pressure (MAP), typically 65 mmHg.
* **Typical Effective Range:** 0.05 to 0.5 mcg/kg/min.
* **Maximum:** No defined absolute maximum, but doses >1 mcg/kg/min are associated with significant ischemic risk and refractory shock.
## Pediatric Dosing
* **Initial:** 0.05 to 0.1 mcg/kg/min continuous IV infusion.
* **Titration:** Titrate to effect in increments of 0.05 mcg/kg/min.
* **Maximum:** Up to 2 mcg/kg/min is often cited in critical care literature, though expert consensus emphasizes titration to physiological endpoints rather than fixed maximums.
* *Note: Always verify doses against institutional weight-based protocols.*
## Dose Adjustments
* **Renal/Hepatic:** No formal dose adjustments; however, patients with organ dysfunction may have altered sensitivity.
* **Tapering:** Must be tapered gradually to prevent rebound hypotension.
## Contraindications
* Hypersensitivity to norepinephrine or bisulfites.
* Profound hypotension primarily due to uncorrected hypovolemia (volume resuscitation must precede or accompany vasopressor initiation).
## Adverse Effects
* **Extravasation:** Risk of severe tissue necrosis and sloughing (treat with phentolamine if extravasation occurs).
* **Cardiovascular:** Hypertension, bradycardia (reflex), arrhythmias, myocardial ischemia.
* **Peripheral:** Digital/mesenteric ischemia (peripheral cyanosis).
## Key Drug Interactions
* **MAO Inhibitors/TCAs:** May cause severe, prolonged hypertensive crisis.
* **Beta-blockers:** May result in unopposed alpha-mediated vasoconstriction and worsening hypertension.
* **Halogenated Anesthetics:** Increase cardiac sensitivity to catecholamines, increasing risk of arrhythmias.
## Monitoring
* **Hemodynamics:** Continuous MAP monitoring via arterial line is strongly recommended.
* **Cardiac:** Continuous ECG monitoring for arrhythmias.
* **Perfusion:** Monitor limb temperature and capillary refill to assess for peripheral vasoconstriction.
* **IV Access:** Frequent assessment of infusion site for infiltrates/extravasation.
## Clinical Pearls
* **Central Line:** Always administer via a large-bore central venous catheter when feasible. If peripheral administration is necessary, use a large vein (e.g., antecubital) and limit duration and concentration.
* **Dilution:** Commonly diluted in 5% Dextrose (D5W) to prevent oxidation; check local stability requirements.
* **Volume Status:** Norepinephrine is not a substitute for fluid resuscitation; evaluate for hypovolemia first.
* **Vasopressin:** Consider adding vasopressin (0.03–0.04 units/min) if norepinephrine requirements are persistently high to allow for titration down.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical protocols, dosing strategies, and institutional guidelines vary significantly. Always verify current prescribing information, package inserts, and local clinical guidelines before administering medication.
