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# Norepinephrine
## Overview
Norepinephrine is a potent vasopressor and inotropic agent used to increase blood pressure and systemic vascular resistance. It acts primarily on alpha-1 adrenergic receptors causing vasoconstriction, and also has some beta-1 adrenergic receptor activity, increasing heart rate and contractility.
## Primary Indications
* Severe Hypotension (e.g., shock, sepsis)
* Cardiac arrest (as an alternative to epinephrine in some protocols)
## Adult Dosing
* **Hypotension/Shock:** Typically initiated at 0.01 to 0.1 mcg/kg/min intravenously. The dose can be titrated upward based on hemodynamic response, usually up to 1 mcg/kg/min, and sometimes higher in refractory shock (e.g., up to 3 mcg/kg/min or more). Specific target goals (e.g., MAP of 65 mmHg) should guide titration.
## Pediatric Dosing
* **Hypotension/Shock:** Typically initiated at 0.05 to 0.1 mcg/kg/min intravenously. Titration is usually based on clinical response and hemodynamics, with doses potentially ranging from 0.01 to 2 mcg/kg/min. Exact dosing and titration targets are often guided by local pediatric critical care protocols.
* **Cardiac Arrest:** In some pediatric advanced life support (PALS) protocols, it may be used as an alternative to epinephrine. Dosing would follow specific PALS guidelines.
## Dose Adjustments
No specific dose adjustments are routinely recommended for hepatic or renal impairment, as the drug is primarily metabolized by the liver and kidneys and has a short half-life. However, prolonged use may require careful monitoring in patients with severe organ dysfunction.
## Contraindications
* Hypersensitivity to norepinephrine
* Should not be used as the sole agent to correct hypotension due to hypovolemia; volume resuscitation should be addressed first.
## Adverse Effects
* **Cardiovascular:** Arrhythmias (tachycardia, bradycardia, ventricular arrhythmias), hypertension, peripheral ischemia, reflex bradycardia, extravasation leading to tissue necrosis.
* **Central Nervous System:** Headache, anxiety, dizziness.
* **Respiratory:** Dyspnea.
* **Other:** Pale skin, sweating, nausea, vomiting.
## Key Drug Interactions
* **Monoamine Oxidase Inhibitors (MAOIs):** Can potentiate the hypertensive effects of norepinephrine. Concurrent use is generally contraindicated or requires extreme caution and dose reduction.
* **Tricyclic Antidepressants (TCAs):** May potentiate the pressor response.
* **Anesthetics (e.g., halogenated anesthetics):** May increase myocardial irritability and risk of arrhythmias.
* **Alpha and Beta Blockers:** May interfere with the desired effects of norepinephrine.
## Monitoring
* Continuous blood pressure monitoring (arterial line preferred for titration).
* Heart rate and rhythm.
* Urine output.
* Signs of peripheral perfusion (e.g., skin color, temperature, capillary refill).
* Central venous pressure (CVP) or other hemodynamic parameters as guided by protocol.
* Assess for signs of extravasation.
## Clinical Pearls
* Norepinephrine should be administered via a central venous catheter to minimize the risk of extravasation and tissue necrosis. If extravasation occurs, stop the infusion immediately and infiltrate the affected area with phentolamine.
* Always ensure adequate volume status before or concurrent with norepinephrine initiation.
* Titrate to achieve target Mean Arterial Pressure (MAP) and adequate end-organ perfusion, not just a specific dose.
* The infusion should be gradually tapered off to avoid abrupt drops in blood pressure.
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*This information is intended for healthcare professionals and does not substitute for professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines for complete details.*
