Please check your internet connection and try again.
# Norepinephrine
## Overview
Norepinephrine is a potent vasopressor and inotropic agent that acts primarily on alpha-1 adrenergic receptors, causing vasoconstriction, and to a lesser extent on beta-1 adrenergic receptors, increasing heart rate and contractility.
## Primary Indications
* Treatment of hypotension and shock, particularly septic shock and cardiogenic shock.
## Adult Dosing
* **Initiation:** 0.01 to 0.03 mcg/kg/min intravenously (IV).
* **Titration:** Increase dose by 0.01 to 0.02 mcg/kg/min every 5 to 15 minutes as needed to achieve target blood pressure (e.g., mean arterial pressure [MAP] > 65 mmHg).
* **Maximum Dose:** Typically 0.1 to 0.3 mcg/kg/min, but higher doses may be used in refractory cases.
* **Note:** Dosing is highly individualized and guided by patient response and hemodynamics.
## Pediatric Dosing
* **Initiation:** 0.05 to 0.1 mcg/kg/min intravenously (IV), may start at lower doses and titrate up.
* **Titration:** Titrate to desired hemodynamic effect, typically increasing by 0.05 to 0.2 mcg/kg/min every 10-15 minutes.
* **Maximum Dose:** Typically 1 to 2 mcg/kg/min, but higher doses may be necessary.
* **Note:** Pediatric dosing often follows institutional protocols and expert recommendations due to variability in response.
## Dose Adjustments
* No specific dose adjustments are routinely required for hepatic or renal impairment, as norepinephrine is metabolized by MAO and COMT and cleared by reuptake. However, prolonged use may require increased doses in patients with liver dysfunction.
## Contraindications
* Hypersensitivity to norepinephrine.
* Patients with known or suspected peripheral vascular thrombosis (risk of exacerbation).
## Adverse Effects
* **Cardiovascular:** Hypertension, bradycardia (reflex), arrhythmias, peripheral ischemia, gangrene (with extravasation), myocardial infarction, pulmonary edema.
* **Central Nervous System:** Headache, anxiety, tremors, dizziness.
* **Other:** Tissue necrosis at injection site (if extravasation occurs), decreased blood flow to vital organs (kidneys, brain) at very high doses.
## Key Drug Interactions
* **Monoamine Oxidase Inhibitors (MAOIs):** Potentiated pressor response; concurrent use is generally contraindicated.
* **Tricyclic Antidepressants (TCAs):** Potentiated pressor response; use with caution.
* **Beta-Blockers:** May antagonize beta-1 effects; may unmask alpha-mediated vasoconstriction, leading to severe hypertension.
* **Alpha-Blockers:** May antagonize alpha-1 effects, reducing efficacy.
* **Ergot Alkaloids:** Potentiated vasoconstrictive effect.
* **Dobutamine/Isoproterenol:** May compete for beta receptors.
## Monitoring
* Continuous blood pressure monitoring (arterial line preferred).
* Heart rate and rhythm.
* Urine output.
* Peripheral perfusion (e.g., skin temperature, capillary refill).
* Central venous pressure (CVP) or pulmonary artery catheter readings if available.
* Assess for signs of extravasation.
## Clinical Pearls
* Norepinephrine is a first-line vasopressor for septic shock and hypotension.
* Always administer via a central venous catheter to minimize risk of extravasation and tissue necrosis.
* If extravasation occurs, stop infusion immediately, do not flush, and consider infiltration with phentolamine.
* Monitor for paradoxical bradycardia; if it occurs, consider atropine.
* Titrate carefully to achieve target MAP while minimizing adverse effects.
***
**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional guidelines for complete details and to verify this information before making clinical decisions.
