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# Norepinephrine
## Overview
Norepinephrine is a potent catecholamine acting primarily on alpha-1 adrenergic receptors (vasoconstriction) and, to a lesser extent, beta-1 adrenergic receptors (inotropic effect). It is the first-line vasopressor for septic shock.
## Primary Indications
* Acute hypotensive states (e.g., septic shock, cardiogenic shock).
* Adjunct in cardiac arrest (less common).
## Adult Dosing
* **Initial:** 0.01 to 0.05 mcg/kg/min continuous IV infusion.
* **Titration:** Increase by 0.05 to 0.1 mcg/kg/min every 3–5 minutes to achieve target Mean Arterial Pressure (MAP) (typically ≥65 mmHg).
* **Maintenance:** 0.01 to 3 mcg/kg/min.
* *Note:* Local institutional protocols may vary significantly regarding concentration and titration intervals.
## Pediatric Dosing
* **Continuous IV infusion:** 0.01 to 0.5 mcg/kg/min, titrated to effect.
* *Note:* Pediatric dosing is highly protocol-dependent; verify concentration and infusion rates with institutional guidelines.
## Dose Adjustments
* **Renal/Hepatic:** No formal dosage adjustments provided by the manufacturer; monitor for hemodynamic stability.
* **Elderly:** Use caution; lower starting doses may be appropriate due to altered sensitivity.
## Contraindications
* Hypersensitivity to norepinephrine or any component of the formulation.
* Hypotension due to uncorrected blood volume deficit (except as an emergency measure).
## Adverse Effects
* **Cardiovascular:** Bradycardia, arrhythmias, hypertension, myocardial ischemia.
* **Extravasation:** Potent vasoconstrictor causing severe tissue necrosis/sloughing.
* **Peripheral Ischemia:** Fingers, toes, or limbs (rarely).
## Key Drug Interactions
* **MAO Inhibitors / TCAs:** May result in severe, prolonged hypertension; dose reduction of norepinephrine is required.
* **Beta-Blockers:** May cause excessive bradycardia and unopposed alpha-mediated vasoconstriction.
* **Halogenated Hydrocarbons (e.g., Anesthetics):** Increased risk of ventricular arrhythmias.
## Monitoring
* **Hemodynamics:** Continuous MAP monitoring via arterial line is preferred.
* **Efficacy:** Monitor perfusion (urine output, mental status, lactate levels).
* **Safety:** Assess IV site frequently for infiltration/extravasation.
* **Heart Rate/Rhythm:** Continuous ECG monitoring.
## Clinical Pearls
* **Extravasation Management:** If infiltration occurs, infiltrate the site with **phentolamine** (a 5–10 mg dose in 10 mL of saline) as soon as possible to counteract localized vasoconstriction.
* **Line Placement:** Central venous access is strongly preferred due to necrosis risk; if using a peripheral line, utilize a large vein (antecubital or more proximal) for short durations only.
* **Stability:** Avoid administration in the same line as alkaline solutions (precipitation may occur).
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**Educational Disclaimer:** This information is for educational purposes only. Clinical practice is subject to institutional policy and individual patient variables. Always consult your current facility-specific protocols and official prescribing information (package insert) before administering medications.
