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# Norepinephrine
## Overview
Norepinephrine (Levophed) is a potent vasopressor and inotropic agent. It acts primarily on alpha-1 adrenergic receptors, causing vasoconstriction and increasing systemic vascular resistance and blood pressure. It also has beta-1 adrenergic effects, increasing heart rate and contractility.
## Primary Indications
* Treatment of severe hypotension and shock, particularly septic shock and cardiogenic shock, refractory to fluid resuscitation.
## Adult Dosing
* **Initial Infusion:** Typically starts at 0.01 to 0.02 mcg/kg/min.
* **Titration:** Gradually increased to achieve the target mean arterial pressure (MAP), usually ≥ 65 mmHg. Doses can range from 0.01 to 1 mcg/kg/min, and occasionally higher.
* **Maximum Dose:** No absolute maximum dose, titrate to achieve desired hemodynamic effect while monitoring for adverse events. Dosing is highly individualized.
## Pediatric Dosing
* **Initial Infusion:** 0.05 to 0.1 mcg/kg/min.
* **Titration:** Increased as needed to maintain desired blood pressure. Doses can range from 0.05 to 2 mcg/kg/min.
* **Maximum Dose:** No absolute maximum dose; titrate to achieve desired hemodynamic effect. Dosing is highly individualized and often guided by local protocols.
## Dose Adjustments
* No specific dose adjustments for renal or hepatic impairment, as doses are titrated to clinical response.
## Contraindications
* Hypersensitivity to norepinephrine.
* Should not be used as the sole agent to treat hypotension due to hypovolemia.
## Adverse Effects
* **Common:** Hypertension, peripheral ischemia (especially with high doses or prolonged infusion), bradycardia (reflex), arrhythmias, anxiety, headache, tremor.
* **Serious:** Extravasation leading to tissue necrosis, severe hypertension, decreased cardiac output (due to increased SVR), pulmonary edema.
## Key Drug Interactions
* **MAO Inhibitors & Tricyclic Antidepressants:** Can potentiate the pressor effects of norepinephrine, leading to hypertensive crisis. Discontinue MAOIs at least 14 days prior to norepinephrine initiation.
* **Alpha and Beta Blockers:** May antagonize or potentiate effects depending on the specific agent.
* **Anesthetic Agents:** May increase the risk of arrhythmias.
* **Ergot Alkaloids & Oxytocics:** May cause severe persistent hypertension.
## Monitoring
* Continuous blood pressure monitoring (intra-arterial preferred).
* Heart rate and rhythm.
* Central venous pressure (CVP) or pulmonary artery catheter (PAC) for fluid status and cardiac output.
* Urine output.
* Peripheral perfusion (skin temperature, color, capillary refill).
* Infusion site for signs of extravasation.
## Clinical Pearls
* Norepinephrine is a potent vasoactive agent and must be administered via central venous access whenever possible to minimize the risk of extravasation and tissue necrosis.
* Always ensure adequate volume status before initiating or increasing norepinephrine; it should not be used as the sole treatment for hypotension due to hypovolemia.
* Monitor infusion sites closely and have phentolamine readily available for extravasation management.
* Titrate to the lowest effective dose to achieve target MAP, balancing hemodynamic support with the risk of adverse effects.
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*Disclaimer: This information is for educational purposes only and does not substitute for professional medical advice. Always consult current prescribing information and clinical guidelines for the most up-to-date and comprehensive details before making any treatment decisions.*
