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
* Management of severe hypotension and shock, particularly distributive shock (e.g., septic shock, neurogenic shock) and cardiogenic shock.
* Restoration and maintenance of blood pressure.
## Adult Dosing
* **Initial dose:** 0.01 to 0.02 mcg/kg/min by continuous intravenous infusion.
* **Titration:** Increase dose in increments of 0.005 to 0.01 mcg/kg/min every 5-15 minutes until desired mean arterial pressure (MAP) of 65 mmHg or higher is achieved.
* **Maximum dose:** Typically 0.1 mcg/kg/min, but doses up to 0.2 mcg/kg/min or higher may be used in refractory shock under expert guidance.
## Pediatric Dosing
* **Initial dose:** 0.05 to 0.1 mcg/kg/min by continuous intravenous infusion.
* **Titration:** Increase dose as needed. Specific titration parameters may vary based on institutional protocols.
* **Maximum dose:** Doses up to 1-2 mcg/kg/min have been reported, but higher doses are associated with increased risk.
## Dose Adjustments
* **Renal impairment:** No specific dose adjustment is typically required, but efficacy and safety may be altered. Monitor closely.
* **Hepatic impairment:** No specific dose adjustment is typically required, but efficacy and safety may be altered. Monitor closely.
## Contraindications
* Hypersensitivity to norepinephrine.
* Hypotension secondary to hypovolemia (should be corrected with volume resuscitation first).
* Use during cyclopropane and halogenated hydrocarbon anesthesia (risk of severe hypertension and arrhythmias).
## Adverse Effects
* **Cardiovascular:** Hypertension, bradycardia (reflex), arrhythmias, peripheral ischemia, tissue necrosis (extravasation).
* **Other:** Headache, anxiety, dizziness, tremor, dyspnea, extravasation leading to skin necrosis.
## Key Drug Interactions
* **Monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants (TCAs):** Potentiate pressor effects, potentially leading to hypertensive crisis. Norepinephrine should be used with extreme caution or avoided in patients taking these agents.
* **Alpha-adrenergic blockers:** May decrease pressor effects.
* **Beta-adrenergic blockers:** May blunt beta-1 effects.
* **Ergot alkaloids and oxytocics:** May potentiate pressor effects.
* **Anesthetics:** Halogenated anesthetics can increase myocardial irritability and sensitize the heart to catecholamines, increasing the risk of arrhythmias.
## Monitoring
* **Hemodynamic parameters:** Continuous blood pressure monitoring (intra-arterial preferred), heart rate, and cardiac rhythm.
* **Urine output:** To assess end-organ perfusion.
* **Peripheral circulation:** Assess extremities for color, temperature, and capillary refill.
* **Infusion site:** Monitor closely for signs of extravasation.
## Clinical Pearls
* Norepinephrine is a potent vasoconstrictor and should be infused through a central venous catheter whenever possible to minimize the risk of extravasation and tissue necrosis.
* If extravasation occurs, immediately stop the infusion, aspirate any residual drug from the line, and infiltrate the affected area with phentolamine (an alpha-adrenergic blocker) to antagonize the vasoconstriction.
* Titration should be guided by the desired hemodynamic response and patient tolerance.
* Ensure adequate volume resuscitation before initiating or in conjunction with norepinephrine therapy.
***
*This information is intended for healthcare professionals. Always consult the official prescribing information and relevant clinical guidelines for complete and up-to-date details. Dosing and management may vary based on individual patient factors and institutional protocols.*
