Please check your internet connection and try again.
# Norepinephrine
## Overview
Norepinephrine is a potent vasopressor and inotropic agent. It acts primarily on alpha-1 adrenergic receptors, causing peripheral vasoconstriction and a subsequent increase in blood pressure. It also has some beta-1 adrenergic activity, which can increase heart rate and contractility.
## Primary Indications
* Severe hypotension, particularly in the setting of septic shock, cardiogenic shock, or anaphylactic shock, when other vasopressors are ineffective or contraindicated.
* To restore and maintain adequate blood pressure and perfusion.
## Adult Dosing
* **Starting Dose:** 0.01 to 0.02 mcg/kg/min IV infusion.
* **Titration:** Gradually increase the dose in increments of 0.01 to 0.02 mcg/kg/min every 5 to 15 minutes until the target blood pressure (e.g., mean arterial pressure [MAP] ≥ 65 mmHg) is achieved.
* **Maximum Dose:** Typically 0.1 to 0.3 mcg/kg/min IV infusion, though higher doses may be used in select refractory cases under close monitoring.
## Pediatric Dosing
* **Starting Dose:** 0.05 to 0.1 mcg/kg/min IV infusion.
* **Titration:** Increase dose as needed to maintain target MAP. Doses can range from 0.01 to 2 mcg/kg/min. Dosing is highly individualized and guided by hemodynamic response.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment is typically required, but caution and close monitoring are advised due to potential accumulation.
* **Hepatic Impairment:** No specific dose adjustment is typically required, but caution and close monitoring are advised.
## Contraindications
* Hypersensitivity to norepinephrine.
* Concurrent use of monoamine oxidase inhibitors (MAOIs) or within 14 days of discontinuing MAOIs.
* Severe heart disease or hypotension due to hypovolemia without adequate fluid resuscitation.
## Adverse Effects
* **Cardiovascular:** Hypertensive crisis, reflex bradycardia, arrhythmias, peripheral ischemia, tissue necrosis (if extravasation occurs), angina, palpitations.
* **Central Nervous System:** Headache, anxiety, dizziness, tremor.
* **Other:** Dyspnea, nausea, vomiting, decreased urine output.
## Key Drug Interactions
* **MAOIs:** Potentiate hypertensive crisis.
* **Tricyclic Antidepressants (TCAs) and other sympathomimetics:** Increased risk of hypertensive crisis and arrhythmias.
* **Beta-blockers:** May decrease the inotropic and chronotropic effects of norepinephrine. Unopposed alpha-stimulation can occur, leading to severe hypertension.
* **Alpha-blockers:** May antagonize the pressor effect.
* **Ergot alkaloids, oxytocin:** May cause severe hypertension.
* **Anesthetic agents (e.g., cyclopropane, halothane):** May increase myocardial irritability and risk of arrhythmias.
## Monitoring
* **Hemodynamics:** Continuous arterial blood pressure monitoring is essential. Heart rate, cardiac output (if available), and central venous pressure should also be monitored.
* **Perfusion:** Monitor urine output, skin temperature, capillary refill, and mental status.
* **ECG:** To detect arrhythmias.
* **Fluid Status:** Assess volume status closely; adequate fluid resuscitation is critical before and during norepinephrine use.
* **Infusion Site:** Inspect regularly for signs of extravasation.
## Clinical Pearls
* Norepinephrine should be administered via a central venous catheter to minimize the risk of extravasation and tissue necrosis.
* If extravasation occurs, stop the infusion immediately and infiltrate the affected area with phentolamine mesylate.
* Adequate fluid resuscitation is paramount before initiating or escalating norepinephrine. It should not be used as a sole therapy for hypotension due to hypovolemia.
* Gradually taper norepinephrine infusion when discontinuing to avoid sudden drops in blood pressure.
* Norepinephrine is often considered a first-line vasopressor in septic shock.
***
**Disclaimer:** This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines for complete details. Dosing and management may vary based on individual patient factors and local protocols.
