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# Norepinephrine
## Overview
Norepinephrine is a vasopressor and inotropic agent that stimulates alpha-adrenergic receptors, causing vasoconstriction and an increase in peripheral vascular resistance and systolic blood pressure. It also has some beta-1 adrenergic activity, leading to increased myocardial contractility.
## Primary Indications
* Treatment of severe hypotension and shock (e.g., septic shock, cardiogenic shock) to maintain adequate tissue perfusion.
## Adult Dosing
* **Initial infusion rate:** 0.01 to 0.02 mcg/kg/minute.
* **Titration:** Increase dose incrementally every 5-10 minutes as needed to achieve target mean arterial pressure (MAP) (often target is MAP ≥ 65 mmHg).
* **Maintenance:** Doses typically range from 0.01 to 0.3 mcg/kg/minute.
* **Maximum dose:** Doses up to 1 mcg/kg/minute may be required in severe cases; doses higher than 1 mcg/kg/minute have been used but are less common and require extreme caution. Local protocols may define a maximum.
## Pediatric Dosing
* **Initial infusion rate:** 0.05 to 0.1 mcg/kg/minute.
* **Titration:** Increase dose as needed to support blood pressure.
* **Maintenance:** Doses typically range from 0.05 to 2 mcg/kg/minute.
* **Maximum dose:** Doses up to 2 mcg/kg/minute are generally considered the maximum; however, higher doses may be used in specific critical situations under expert guidance. Dosing is highly individualized and often guided by institutional protocols and patient response.
## Dose Adjustments
* No specific dose adjustments are typically required for hepatic or renal impairment, as norepinephrine is metabolized and does not accumulate significantly. However, careful monitoring of response and potential side effects is crucial in these populations.
## Contraindications
* Hypersensitivity to norepinephrine.
* Generally contraindicated in patients with hypotensive anesthesia due to pheochromocytoma or specific types of syncope.
## Adverse Effects
* **Cardiovascular:** Hypertension, bradycardia (reflex), arrhythmias, peripheral ischemia, myocardial infarction, reduced blood flow to vital organs.
* **Local:** Extravasation leading to tissue necrosis; careful IV site monitoring and central venous access are recommended.
* **Other:** Headache, anxiety, confusion, nausea, vomiting, decreased urine output.
## Key Drug Interactions
* **Anesthetics:** May potentiate arrhythmias.
* **MAO Inhibitors and Tricyclic Antidepressants:** May prolong and intensify the pressor effects of norepinephrine. Concurrent use is generally avoided.
* **Beta-blockers:** Can lead to unopposed alpha-stimulation, potentially causing severe hypertension.
* **Oxytocics:** May cause severe hypertension.
## Monitoring
* Continuous arterial blood pressure monitoring.
* Heart rate and rhythm.
* Urine output.
* Peripheral perfusion (e.g., skin color, temperature, capillary refill).
* Central venous pressure (if available).
* Signs of extravasation.
## Clinical Pearls
* Always administer norepinephrine via a central venous catheter to minimize the risk of extravasation and tissue necrosis.
* Have phentolamine readily available for potential extravasation management.
* Norepinephrine should be diluted in a compatible IV solution (e.g., D5W, NS, D5NS) before administration.
* Titrate to the lowest effective dose to maintain adequate organ perfusion, not just a specific blood pressure number.
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*This information is intended for healthcare professionals and does not replace the need to consult the official prescribing information or local institutional protocols. Always verify current drug information before administration.*
