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# Norepinephrine
## Overview
Norepinephrine is a potent vasopressor and inotropic agent that acts primarily on alpha-1 adrenergic receptors, causing peripheral vasoconstriction and increasing blood pressure. It also has some beta-1 adrenergic activity, increasing heart rate and contractility.
## Primary Indications
* Treatment of hypotension and shock, including septic shock and cardiogenic shock, unresponsive to fluid resuscitation.
## Adult Dosing
* **Usual dose:** 0.01 to 0.3 mcg/kg/min IV infusion.
* **Initiation:** Typically started at 0.01 to 0.02 mcg/kg/min.
* **Titration:** Titrate infusion rate to achieve target mean arterial pressure (MAP), often 65 mmHg or higher, or to improve perfusion.
* **Maximum dose:** Doses higher than 0.3 mcg/kg/min are rarely used but may be necessary in refractory hypotension. Dosing is highly individualized.
## Pediatric Dosing
* **Usual dose:** 0.05 to 2 mcg/kg/min IV infusion.
* **Initiation:** Typically started at 0.05 mcg/kg/min.
* **Titration:** Titrate to achieve target MAP (e.g., greater than gestational age + 10 mmHg in neonates, or 65 mmHg in older children) or improve perfusion.
* **Maximum dose:** Generally not to exceed 2 mcg/kg/min, though higher doses may be used cautiously under expert guidance.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment. Closely monitor hemodynamic response.
* **Hepatic Impairment:** No specific dose adjustment. Closely monitor hemodynamic response.
## Contraindications
* Hypersensitivity to norepinephrine or its components.
* Hypotension due to relative hypovolemia (should be corrected with fluid resuscitation prior to or concurrently with norepinephrine).
## Adverse Effects
* **Common:** Hypertension, bradycardia (reflex), peripheral ischemia, anxiety, headache, tremor.
* **Serious:** Arrhythmias, myocardial infarction, extravasation leading to tissue necrosis (antidote: phentolamine).
## Key Drug Interactions
* **General anesthetics:** May potentiate arrhythmias.
* **Beta-blockers:** May cause unopposed alpha-adrenergic stimulation, leading to severe hypertension.
* **MAO inhibitors & Tricyclic Antidepressants:** Can potentiate the pressor response; avoid or use with extreme caution and reduced doses.
* **Oxytocics:** May cause severe hypertension.
## Monitoring
* Continuous ECG and blood pressure monitoring.
* Central venous pressure (CVP) and pulmonary artery pressures if available.
* Urine output.
* Peripheral perfusion (e.g., skin temperature, capillary refill, mental status).
* Infusion site 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, aspirate any residual drug, and infiltrate the affected area with phentolamine.
* It is crucial to ensure adequate volume status before initiating or titrating norepinephrine.
* Dosing is highly individualized and guided by clinical response and hemodynamic targets, which may vary by institution and patient population.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols for complete details before making clinical decisions.*
