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# Norepinephrine
## Overview
Norepinephrine is a potent alpha-adrenergic agonist and a weaker beta-1 adrenergic agonist. It causes vasoconstriction, increasing systemic vascular resistance and blood pressure, and has a positive inotropic effect on the heart.
## Primary Indications
* Treatment of hypotension and shock (e.g., septic shock, cardiogenic shock).
## Adult Dosing
* **Initiation:** Typically started at 0.01 to 0.03 mcg/kg/min IV.
* **Titration:** Dose is titrated based on hemodynamic response (blood pressure, heart rate, cardiac output) up to a maximum of 0.2 mcg/kg/min IV. Doses may exceed this in refractory shock but require close hemodynamic monitoring.
* **Infusion:** Requires a central venous catheter for administration due to its potent vasoconstrictive properties, which can cause tissue necrosis if extravasated.
## Pediatric Dosing
* **Initiation:** Typically started at 0.05 to 0.1 mcg/kg/min IV.
* **Titration:** Dose is titrated based on hemodynamic response, usually up to 1 mcg/kg/min IV. Some protocols may allow higher doses.
* **Infusion:** Requires a central venous catheter for administration.
## Dose Adjustments
* No specific dose adjustments are typically required for hepatic or renal impairment, as norepinephrine is rapidly metabolized. However, careful titration is essential in all patients.
## Contraindications
* Hypersensitivity to norepinephrine.
* Use during general anesthesia with cyclopropane or halogenated hydrocarbon anesthetics may cause severe hypertension and arrhythmias.
## Adverse Effects
* **Cardiovascular:** Arrhythmias (including ventricular tachycardia, fibrillation), bradycardia, hypertension, peripheral ischemia, vasoconstriction, decreased cardiac output.
* **Other:** Anxiety, headache, dizziness, tremor, extravasation leading to tissue necrosis.
## Key Drug Interactions
* **Monoamine Oxidase Inhibitors (MAOIs):** Potentiate pressor effects, potentially causing hypertensive crisis. Avoid concurrent use or reduce norepinephrine dose significantly.
* **Tricyclic Antidepressants (TCAs) and other sympathomimetics:** Can potentiate pressor response. Use with caution.
* **Beta-blockers:** May cause unopposed alpha-stimulation, leading to severe hypertension.
* **Alpha-blockers:** May reduce pressor effects.
## Monitoring
* **Hemodynamics:** Continuous blood pressure monitoring (arterial line preferred), heart rate, central venous pressure, pulmonary artery pressures (if available), cardiac output.
* **Urine Output:** Monitor for adequate renal perfusion.
* **Peripheral Perfusion:** Assess for signs of ischemia (e.g., skin color, temperature, capillary refill).
* **Infusion Site:** Monitor closely for signs of extravasation.
## Clinical Pearls
* Norepinephrine is a first-line agent for septic shock to restore mean arterial pressure.
* It should be administered via a central line to prevent extravasation and resulting tissue necrosis.
* If extravasation occurs, stop the infusion and inject phentolamine locally.
* Gradually taper the infusion to avoid abrupt hypotension.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines for complete details before making any treatment decisions. Dosing and management may vary based on individual patient factors and local institutional protocols.
