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# Norepinephrine
## Overview
Norepinephrine (Levophed) is a potent vasopressor and inotropic agent that acts primarily on alpha-1 adrenergic receptors, causing vasoconstriction, and to a lesser extent on beta-1 receptors, increasing heart rate and contractility.
## Primary Indications
* Treatment of severe hypotension and shock, particularly septic shock and cardiogenic shock, when other agents are insufficient.
* Restoration and maintenance of blood pressure.
## Adult Dosing
* **Starting Dose:** Typically 0.01 to 0.02 mcg/kg/min.
* **Titration:** May be increased in increments of 0.01 to 0.02 mcg/kg/min every 5-15 minutes as needed to achieve target blood pressure.
* **Maximum Dose:** Generally considered to be 1 mcg/kg/min, although higher doses may be used in refractory cases under expert guidance.
## Pediatric Dosing
* **Starting Dose:** 0.05 to 0.1 mcg/kg/min.
* **Titration:** May be increased in increments of 0.05 to 0.1 mcg/kg/min every 5-15 minutes as needed.
* **Maximum Dose:** Up to 1 mcg/kg/min or higher based on clinical response and institutional protocols. Dosing in pediatrics is highly variable and often guided by institutional protocols.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment is usually recommended, but caution is advised due to potential accumulation and prolonged effects.
* **Hepatic Impairment:** No specific dose adjustment is usually recommended, but caution is advised.
## Contraindications
* Hypersensitivity to norepinephrine.
* In patients with mesenteric or peripheral vascular thrombosis, as it may increase ischemia.
## Adverse Effects
* **Cardiovascular:** Hypertension, reflex bradycardia, arrhythmias, peripheral ischemia, digital ischemia, extravasation leading to tissue necrosis.
* **Other:** Headache, anxiety, tremor, dyspnea.
## Key Drug Interactions
* **Monoamine Oxidase Inhibitors (MAOIs):** Potentiates pressor response; concurrent use is generally contraindicated.
* **Tricyclic Antidepressants (TCAs) and other Norepinephrine Reuptake Inhibitors:** May potentiate the pressor effects; use with caution.
* **General Anesthetics:** May increase the risk of arrhythmias.
* **Beta-blockers:** May cause unopposed alpha-stimulation leading to severe hypertension.
## Monitoring
* Continuous blood pressure monitoring (arterial line preferred).
* Heart rate and rhythm.
* Urine output.
* Signs of peripheral perfusion (e.g., skin color, temperature, capillary refill).
* Infusion site for signs of extravasation.
## Clinical Pearls
* Norepinephrine is typically administered via a central venous catheter due to its potent vasoconstricting properties and risk of tissue necrosis with extravasation.
* If extravasation occurs, discontinue infusion immediately, do not flush the line. Administer phentolamine (an alpha-blocker) infiltrated into the affected area as soon as possible.
* Titrate to achieve target MAP, not necessarily a specific systolic blood pressure.
* It is a potent agent and should be used with extreme caution and close monitoring.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines before making therapeutic decisions. Dosing and administration can vary based on patient-specific factors and institutional protocols.*
