Please check your internet connection and try again.
# Norepinephrine
## Overview
Norepinephrine is a potent vasopressor and inotropic agent that acts primarily on alpha-adrenergic receptors, causing vasoconstriction, and to a lesser extent on beta1-adrenergic receptors, increasing heart rate and contractility.
## Primary Indications
* Severe hypotension and shock, particularly in distributive shock (e.g., septic shock, neurogenic shock).
* Cardiogenic shock refractory to other treatments.
## Adult Dosing
* **Initial infusion rate:** 0.01 to 0.02 mcg/kg/min.
* **Titration:** Increase in increments of 0.005 to 0.01 mcg/kg/min every 2 to 5 minutes until desired mean arterial pressure (MAP) is achieved (typically target MAP ≥ 65 mmHg).
* **Maximum infusion rate:** Generally 0.1 mcg/kg/min, but may be increased up to 1 mcg/kg/min in refractory cases, although higher doses are associated with increased risk of adverse effects and mortality. Dosing is highly individualized based on patient response.
## Pediatric Dosing
* **Initial infusion rate:** 0.05 to 0.1 mcg/kg/min.
* **Titration:** Increase in increments of 0.05 to 0.1 mcg/kg/min every 5 to 10 minutes.
* **Maximum infusion rate:** Typically 1 mcg/kg/min. Target MAP is usually age-specific (e.g., >30 mmHg in neonates, >40 mmHg in infants, >50 mmHg in children, >65 mmHg in adolescents). Dosing is highly individualized and often guided by local pediatric critical care protocols.
## Dose Adjustments
* **Renal impairment:** No specific dose adjustment. Monitor closely for effects.
* **Hepatic impairment:** No specific dose adjustment. Monitor closely for effects.
## Contraindications
* Hypersensitivity to norepinephrine.
* Severe hypotension with hypoperfusion when vasodilatory shock is present (use with caution and after volume resuscitation).
* Generally avoided in patients with mesenteric or peripheral vascular thrombosis due to risk of worsening ischemia.
## Adverse Effects
* **Cardiovascular:** Hypertensive crisis, bradycardia (reflex), arrhythmias, peripheral ischemia, tissue necrosis (extravasation), decreased cardiac output (at higher doses due to increased afterload).
* **Central Nervous System:** Headache, anxiety, confusion, dizziness.
* **Metabolic:** Hyperglycemia.
* **Other:** Respiratory distress.
## Key Drug Interactions
* **Anesthetic agents (e.g., cyclopropane, halothane):** May increase myocardial irritability and risk of arrhythmias.
* **Monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants (TCAs):** Can potentiate the pressor effect of norepinephrine, leading to severe hypertension. Avoid concurrent use or use with extreme caution and significantly reduced doses.
* **Alpha- and beta-adrenergic blocking agents:** May antagonize effects.
* **Guanethidine, methyldopa:** May reduce the hypotensive effects of these agents.
* **Ergot alkaloids, oxytocin:** May cause severe hypertension.
## Monitoring
* **Hemodynamics:** Continuous blood pressure monitoring (intra-arterial preferred), heart rate, cardiac output (if available).
* **Urine output.**
* **Peripheral perfusion:** Assess skin temperature, color, capillary refill, and presence of pulses.
* **Mental status.**
* **Electrolytes and glucose.**
## Clinical Pearls
* Norepinephrine is typically administered via a central venous catheter to minimize risk of extravasation.
* If extravasation occurs, stop the infusion, aspirate any remaining drug, and infiltrate the area with phentolamine.
* Titrate to achieve target MAP and adequate end-organ perfusion, not just a specific number.
* May be used in combination with other vasopressors or inotropes depending on the underlying shock state.
* Consider a continuous infusion of phentolamine or saline flush for potential extravasation management.
***
*This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and clinical guidelines before administering any medication.*
