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# Norepinephrine
## Overview
Norepinephrine is a vasopressor that acts primarily on alpha-1 adrenergic receptors, causing vasoconstriction and increasing systemic vascular resistance. It also has beta-1 adrenergic effects, increasing heart rate and contractility, though these are less pronounced than its alpha-1 effects.
## Primary Indications
* Treatment of hypotension and shock, particularly septic shock and cardiogenic shock.
## Adult Dosing
* **Administration:** Intravenous infusion.
* **Usual Dose:** Start at 0.01 to 0.02 mcg/kg/min.
* **Titration:** Titrate upwards based on clinical response (e.g., mean arterial pressure [MAP] goal). Doses up to 0.1 mcg/kg/min are common.
* **Maximum Dose:** Doses up to 1 mcg/kg/min or higher may be necessary in severe cases. Precise maximums can depend on local protocol and patient tolerance.
## Pediatric Dosing
* **Administration:** Intravenous infusion.
* **Usual Dose:** Start at 0.05 to 0.1 mcg/kg/min.
* **Titration:** Titrate based on clinical response to achieve target blood pressure.
* **Maximum Dose:** Doses up to 1 mcg/kg/min may be used, but higher doses are often managed by pediatric critical care specialists. Specific maximums vary by institution.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment is typically required, but close monitoring is essential.
* **Hepatic Impairment:** No specific dose adjustment is typically required, but close monitoring is essential.
## Contraindications
* Hypersensitivity to norepinephrine.
* Should not be used as the sole agent to treat hypotension due to hypovolemia.
## Adverse Effects
* **Common:** Hypertension, reflex bradycardia, peripheral ischemia, anxiety, headache, dizziness, tremors, nausea.
* **Severe:** Arrhythmias, myocardial infarction, extravasation leading to tissue necrosis (requires immediate attention and potential infiltration with phentolamine).
## Key Drug Interactions
* **Monoamine Oxidase Inhibitors (MAOIs) and Tricyclic Antidepressants (TCAs):** Potentiate the pressor response; avoid concurrent use or use with extreme caution and reduced initial doses.
* **General Anesthetics:** May increase myocardial irritability.
* **Beta-blockers:** May cause unopposed alpha-stimulation leading to severe hypertension.
* **Alpha-blockers:** May antagonize the pressor effects.
* **Ergot Alkaloids:** May potentiate vasopressor effects.
## Monitoring
* Continuous hemodynamic monitoring: Blood pressure, heart rate, rhythm.
* Urine output.
* Peripheral perfusion (skin color, temperature, capillary refill).
* Central venous pressure (if available).
* Infusion site for signs of extravasation.
## Clinical Pearls
* Norepinephrine is often considered a first-line vasopressor in septic shock.
* It should be administered via a central venous catheter whenever possible to minimize the risk of extravasation.
* If extravasation occurs, stop the infusion immediately and infiltrate the affected area with phentolamine.
* Titrate to the lowest effective dose to maintain adequate perfusion pressure.
* Always correct hypovolemia before or concurrently with the initiation of norepinephrine.
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**Disclaimer:** This information is intended for clinical professionals and does not replace a thorough review of the current Prescribing Information or local protocols. Always verify current dosing, indications, and safety information with official drug references and institutional guidelines before use.
