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# Norepinephrine
## Overview
Norepinephrine is a vasopressor and inotrope that acts primarily on alpha-1 adrenergic receptors, causing vasoconstriction, and also on beta-1 adrenergic receptors, increasing heart rate and contractility.
## Primary Indications
* Treatment of severe hypotension and shock, particularly septic shock and cardiogenic shock, to maintain adequate organ perfusion.
## Adult Dosing
* **Intravenous infusion:** Typically initiated at 0.01 to 0.05 mcg/kg/minute, titrated to achieve target mean arterial pressure (MAP), often $\ge$ 65 mmHg.
* **Maximum dose:** Doses up to 0.1 mcg/kg/minute or higher may be required in some patients; however, higher doses are associated with increased risk of adverse effects. Titrate based on patient response and institutional guidelines.
## Pediatric Dosing
* **Intravenous infusion:** Typically initiated at 0.05 to 0.1 mcg/kg/minute, titrated to achieve target MAP or other hemodynamic goals.
* **Maximum dose:** Doses may be increased up to 0.2 mcg/kg/minute or higher based on clinical response and institutional protocols.
## Dose Adjustments
* No specific dose adjustments for hepatic or renal impairment are established, as doses are typically weight-based and titrated to effect in critically ill patients.
## Contraindications
* Hypersensitivity to norepinephrine.
* Severe peripheral or mesenteric vascular thrombosis (risk of exacerbating ischemia).
## Adverse Effects
* **Common:** Peripheral vasoconstriction (leading to limb ischemia, cold extremities), bradycardia (reflex), hypertension, arrhythmias, anxiety, headache, tissue necrosis at infusion site (extravasation).
* **Less common:** Tachycardia, chest pain, dyspnea.
## Key Drug Interactions
* **MAO inhibitors, tricyclic antidepressants, other sympathomimetics:** Potentiate pressor effects and increase risk of hypertensive crisis. Avoid concurrent use or use with extreme caution and lower initial doses.
* **Beta-blockers:** May unmask unopposed alpha-adrenergic effects, leading to severe hypertension.
* **Anesthetic agents (e.g., cyclopropane, halothane):** May increase myocardial irritability and risk of arrhythmias.
## Monitoring
* **Hemodynamics:** Continuous arterial blood pressure monitoring (MAP), heart rate, rhythm. Central venous pressure (CVP) and cardiac output monitoring may be beneficial.
* **Perfusion:** Urine output, mental status, skin temperature and color, capillary refill.
* **Infusion site:** Assess regularly for signs of extravasation.
## Clinical Pearls
* Administer via a central venous catheter to minimize risk of extravasation and tissue damage.
* Have phentolamine readily available for extravasation management.
* Titrate infusion rate carefully to achieve target MAP while avoiding excessive hypertension.
* Norepinephrine is often a second-line agent after initial fluid resuscitation in septic shock.
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*This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions.*
