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# Norepinephrine
## Overview
Norepinephrine is a vasopressor and inotrope that acts primarily on alpha-1 adrenergic receptors, causing vasoconstriction and increasing blood pressure. It also has some beta-1 adrenergic activity, increasing heart rate and contractility.
## Primary Indications
* Treatment of hypotension, particularly shock (e.g., septic shock, cardiogenic shock) when other agents are insufficient.
## Adult Dosing
* **Loading Dose:** Not typically given.
* **Maintenance Dose:** Start at 0.01 to 0.05 mcg/kg/min IV. Titrate upwards by 0.01 to 0.05 mcg/kg/min every 5-15 minutes until desired blood pressure (e.g., mean arterial pressure [MAP] ≥ 65 mmHg) is achieved.
* **Maximum Dose:** Generally 0.1 mcg/kg/min, but doses up to 1 mcg/kg/min may be used in refractory cases under close monitoring.
## Pediatric Dosing
* **Loading Dose:** Not typically given.
* **Maintenance Dose:** Start at 0.05 to 0.1 mcg/kg/min IV. Titrate upwards by 0.05 to 0.1 mcg/kg/min every 5-15 minutes to achieve target MAP (typically age-adjusted, e.g., in infants, target MAP is generally ≥ gestational age + 2 years).
* **Maximum Dose:** Generally 1 mcg/kg/min.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment. Monitor closely as renal clearance may be affected.
* **Hepatic Impairment:** No specific dose adjustment. Monitor closely as hepatic metabolism may be affected.
## Contraindications
* Hypersensitivity to norepinephrine.
* Use during cyclopropane or halogenated hydrocarbon anesthesia due to potential for severe hypertension and cardiac arrhythmias.
## Adverse Effects
* **Common:** Hypertension, bradycardia (reflex), peripheral ischemia, arrhythmias, anxiety, headache, dizziness, decreased cardiac output (if excessive vasoconstriction).
* **Serious:** Extravasation leading to tissue necrosis (manage with phentolamine).
## Key Drug Interactions
* **Anesthetics (volatile):** Increased risk of arrhythmias.
* **Beta-blockers:** May potentiate alpha-agonist effects, leading to severe hypertension.
* **MAO inhibitors and Tricyclic Antidepressants:** May prolong and intensify the pressor effect of norepinephrine.
## Monitoring
* Continuous ECG monitoring.
* Continuous blood pressure monitoring (arterial line preferred).
* Urine output.
* Peripheral perfusion (e.g., skin color, temperature, capillary refill).
* Central venous pressure and pulmonary artery pressures (if available).
## Clinical Pearls
* Administer via a central venous catheter to minimize risk of peripheral extravasation.
* If extravasation occurs, stop infusion immediately and infiltrate the affected area with phentolamine.
* Norepinephrine is light-sensitive; protect infusions from light.
* Titration should be guided by hemodynamic response and patient tolerance.
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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 any treatment decisions.*
