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# Norepinephrine
## Overview
Norepinephrine is a potent vasopressor that acts primarily on alpha-1 adrenergic receptors, causing vasoconstriction and increasing systemic vascular resistance. It also has beta-1 adrenergic activity, increasing heart rate and contractility.
## Primary Indications
* Treatment of hypotension and shock, particularly septic shock and cardiogenic shock, unresponsive to fluid resuscitation.
## Adult Dosing
* **Initial Infusion:** 0.01 to 0.1 mcg/kg/min IV.
* **Titration:** Titrate infusion rate to achieve target mean arterial pressure (MAP) of 65 mmHg or higher, or as guided by local protocol.
* **Maximum Dose:** Doses up to 1 mcg/kg/min may be required in severe cases, but higher doses are associated with increased risks. Doses exceeding 0.5 mcg/kg/min require careful consideration and monitoring.
## Pediatric Dosing
* **Initial Infusion:** 0.05 to 0.1 mcg/kg/min IV.
* **Titration:** Titrate infusion rate to achieve target MAP greater than the patient's age in years plus 2 mmHg, or as guided by local protocol.
* **Maximum Dose:** Generally considered to be 1 mcg/kg/min, but higher doses may be used cautiously.
## Dose Adjustments
* No specific dose adjustments for renal or hepatic impairment are established. Use with caution and monitor closely.
## Contraindications
* Hypersensitivity to norepinephrine.
* Severe hypotension with metabolic acidosis and hypoxemia if initial volume resuscitation is not adequate.
## Adverse Effects
* **Cardiovascular:** Hypertension, bradycardia, arrhythmias, myocardial infarction, peripheral ischemia, extravasation leading to tissue necrosis.
* **Other:** Headache, anxiety, dizziness, decreased urine output.
## Key Drug Interactions
* **MAO Inhibitors & Tricyclic Antidepressants:** May potentiate the pressor effects of norepinephrine, leading to hypertensive crisis. Discontinue MAOIs at least 14 days prior to norepinephrine initiation.
* **Anesthetic Agents:** May increase the risk of arrhythmias.
* **Beta-Blockers:** May lead to unopposed alpha-stimulation, resulting in severe hypertension.
* **Alpha-Blockers:** May antagonize the pressor effects.
* **Ergot Alkaloids:** Increased risk of vasoconstriction and peripheral ischemia.
## 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 (if available).
* Signs of extravasation.
## Clinical Pearls
* Always initiate with adequate fluid resuscitation before or concurrently with norepinephrine.
* Administer via a central venous catheter if possible to minimize risk of peripheral extravasation. If peripheral administration is necessary, use a large vein and monitor closely for signs of infiltration or necrosis.
* Phentolamine is the recommended antidote for extravasation.
* Short-acting, so titration requires careful and frequent adjustments.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and local protocols before making clinical decisions.*
