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# Norepinephrine
## Overview
Norepinephrine is a potent vasopressor that acts primarily on alpha-1 adrenergic receptors, causing vasoconstriction and increasing systemic vascular resistance. It also has beta-1 adrenergic effects, increasing heart rate and contractility, though these are less pronounced than its alpha-1 effects.
## Primary Indications
* Severe hypotension, particularly that associated with septic shock and other distributive shock states.
* Cardiogenic shock (adjunctive therapy).
## Adult Dosing
* **Initial Dose:** 2 to 10 mcg/minute IV infusion.
* **Titration:** Titrate to achieve target mean arterial pressure (MAP), typically 65 mmHg or higher, or as per local protocol. Doses can be increased up to 30 mcg/minute or higher in refractory shock.
## Pediatric Dosing
* **Initial Dose:** 0.05 to 0.1 mcg/kg/minute IV infusion.
* **Titration:** Titrate to achieve target blood pressure or as per local protocol. Doses can be increased up to 1 mcg/kg/minute, and in some cases, up to 2 mcg/kg/minute.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, as norepinephrine is rapidly metabolized. However, clinical response dictates dosing.
## Contraindications
* Hypersensitivity to norepinephrine.
* Severe hypotension from hypovolemia (requires volume resuscitation first).
* Use with cyclopropane or halogenated hydrocarbon anesthetics (risk of severe arrhythmias).
## Adverse Effects
* Hypertension, reflex bradycardia.
* Peripheral ischemia, skin necrosis (especially with extravasation).
* Arrhythmias (tachycardia, bradycardia).
* Anxiety, headache, dizziness.
* Pulmonary edema.
## Key Drug Interactions
* **MAO Inhibitors and Tricyclic Antidepressants:** Potentiate the pressor response. Avoid concurrent use or use with extreme caution and reduced initial doses.
* **General Anesthetics (e.g., Halothane, Cyclopropane):** Increased risk of arrhythmias.
* **Alpha and Beta Blockers:** May antagonize effects.
## Monitoring
* Continuous blood pressure monitoring (arterial line preferred).
* Heart rate and rhythm.
* Urine output.
* Signs of peripheral ischemia (e.g., skin color, temperature, capillary refill).
* Central venous pressure or pulmonary artery catheter data if available.
* Infusion site for signs of extravasation.
## Clinical Pearls
* Norepinephrine should be infused via a central venous catheter to minimize the risk of extravasation and local tissue damage.
* If extravasation occurs, discontinue the infusion and immediately infiltrate the affected area with phentolamine mesylate.
* It is essential to correct hypovolemia, respiratory compromise, and metabolic acidosis before or concurrently with norepinephrine administration.
* Titrate to the lowest effective dose to achieve hemodynamic goals.
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**Disclaimer:** This information is for educational purposes only and does not substitute for professional medical advice. Always consult the most current prescribing information and your healthcare provider to ensure patient safety and appropriateness of care.
