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# Norepinephrine
## Overview
Norepinephrine is a potent catecholamine with primary alpha-1 adrenergic agonist activity (vasoconstriction) and moderate beta-1 adrenergic activity (inotropic effect). It is the first-line vasopressor for septic shock.
## Primary Indications
* Acute hypotensive states (e.g., septic, cardiogenic, or distributive shock).
* Adjunctive therapy for cardiac arrest unresponsive to standard treatment (off-label).
## Adult Dosing
* **Initial:** 0.05–0.1 mcg/kg/min (or 2–4 mcg/min).
* **Titration:** Titrate by 0.05–0.2 mcg/kg/min every 3–5 minutes based on blood pressure response.
* **Maintenance:** Usual range 0.1–0.5 mcg/kg/min.
* **Maximum:** Doses exceeding 1–3 mcg/kg/min are occasionally used in refractory shock but carry significant risk of end-organ ischemia.
## Pediatric Dosing
* **Initial:** 0.05–0.1 mcg/kg/min.
* **Titration:** Titrate to clinical goal (target Mean Arterial Pressure for age).
* **Refractory Shock:** Up to 1–2 mcg/kg/min may be required in specialized PICU settings.
* *Note: Dosing is highly dependent on institutional protocols.*
## Dose Adjustments
* **Renal/Hepatic:** No formal adjustment guidelines; monitor closely for signs of decreased peripheral perfusion.
* **Weaning:** Gradual tapering is required to prevent rebound hypotension.
## Contraindications
* Hypersensitivity to norepinephrine.
* Hypotension due to uncorrected blood volume depletion (must restore volume prior to or concurrently with vasopressor initiation).
* Mesenteric or peripheral vascular thrombosis (relative contraindication).
## Adverse Effects
* **Cardiovascular:** Hypertension, bradycardia (reflex), arrhythmias, myocardial ischemia.
* **Peripheral:** Extravasation causing tissue necrosis/sloughing.
* **Miscellaneous:** Anxiety, respiratory difficulty, headache.
## Key Drug Interactions
* **MAO Inhibitors/TCAs:** May cause severe, prolonged hypertension.
* **Beta-Blockers:** May antagonize cardiac effects and lead to unopposed alpha-mediated vasoconstriction.
* **Cyclopropane/Halogenated Hydrocarbons:** Increased risk of ventricular arrhythmias.
## Monitoring
* **Continuous:** Blood pressure (ideally via arterial line), heart rate, and ECG.
* **End-organ perfusion:** Urine output, lactic acid levels, mental status, and skin color/temperature of extremities.
* **IV Site:** Frequent assessment for signs of extravasation (pallor, coldness, local pain).
## Clinical Pearls
* **Extravasation Management:** If extravasation occurs, stop the infusion immediately. Phentolamine mesylate (local injection) is the antidote of choice to block alpha-adrenergic vasoconstriction.
* **Central Access:** Strongly recommended to administer via a central venous catheter (CVC) to minimize extravasation risk. Short-term peripheral administration is acceptable in emergencies provided the line is large-bore, proximal (antecubital), and monitored continuously.
* **Fluid Status:** Vasopressors will not be effective if the patient is profoundly hypovolemic. Ensure adequate fluid resuscitation.
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*Disclaimer: This information is for educational purposes and does not replace professional clinical judgment. Always verify dosages, contraindications, and compatibility with local hospital protocols, institutional guidelines, and current package inserts before prescribing or administering medication.*
