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# Norepinephrine
## Overview
Norepinephrine is a vasopressor and inotropic agent that acts on alpha- and beta-adrenergic receptors. It increases vascular tone and myocardial contractility.
## Primary Indications
* Severe hypotension (e.g., shock) unresponsive to adequate fluid resuscitation.
* Cardiac arrest (often part of ACLS algorithms).
## Adult Dosing
* **Hypotension/Shock:** Typically initiated at **2 to 4 mcg/minute (0.01 to 0.02 mcg/kg/minute)** via continuous intravenous infusion. Titrate to achieve target mean arterial pressure (MAP) of **65 mmHg** or higher, or as per local protocol. Doses may be increased as needed, with typical maximums ranging from **0.1 to 0.3 mcg/kg/minute**.
* **Cardiac Arrest:** **1 mg (10 mL of 100 mcg/mL solution) intravenously or intraosseously** every 3 to 5 minutes as per ACLS guidelines.
## Pediatric Dosing
* **Hypotension/Shock:** **0.05 to 0.1 mcg/kg/minute** via continuous intravenous infusion. Titrate to desired hemodynamic effect. Max: **0.1 to 2 mcg/kg/minute**.
* **Cardiac Arrest:** **0.01 mg/kg (10 mcg/kg) intravenously or intraosseously** every 3 to 5 minutes. Repeat doses may be given.
## Dose Adjustments
No dose adjustments are typically needed for hepatic or renal impairment.
## Contraindications
* Hypersensitivity to norepinephrine.
* Hypotension due to hypovolemia (unless used as a temporizing measure while awaiting fluid resuscitation).
* Use during cyclopropane or halogenated hydrocarbon anesthesia (risk of severe arrhythmias).
## Adverse Effects
* **Common:** Tachycardia, bradycardia (reflex), hypertension, peripheral ischemia, anxiety, headache, dizziness, tremor, local tissue necrosis (if extravasation occurs).
* **Less Common:** Arrhythmias, reduced blood flow to vital organs (renal, splanchnic) with prolonged or high-dose infusions.
## Key Drug Interactions
* **Monoamine Oxidase Inhibitors (MAOIs) & Tricyclic Antidepressants (TCAs):** Potentiate hypertensive effects; avoid or use with extreme caution and significantly reduced doses.
* **Beta-blockers:** May blunt the positive inotropic effects of norepinephrine; unopposed alpha-stimulation may lead to severe hypertension.
* **Alpha-blockers:** May antagonize the vasoconstrictive effects.
* **Ergot Alkaloids:** Potentiate vasoconstriction and risk of ischemia.
* **Anesthetic Agents (e.g., halogenated hydrocarbons):** Increased risk of arrhythmias.
## Monitoring
* Continuous hemodynamic monitoring (blood pressure, heart rate).
* Central venous pressure (CVP) and/or pulmonary artery pressures if available.
* Urine output.
* Peripheral perfusion (skin color, temperature, capillary refill).
* Infusion site for signs of extravasation.
* Electrolytes and acid-base status.
## Clinical Pearls
* Norepinephrine is a potent vasoconstrictor and should be administered through a central venous catheter whenever possible to minimize the risk of extravasation and local tissue necrosis.
* If extravasation occurs, stop the infusion and infiltrate the affected area with phentolamine (an alpha-blocker) as soon as possible.
* Titrate to the lowest effective dose to achieve hemodynamic goals and minimize adverse effects.
* Ensure adequate fluid volume resuscitation before or concurrently with norepinephrine administration.
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**Disclaimer:** This information is intended for clinical use and is not a substitute for professional medical advice. Always consult the most current prescribing information, product literature, and institutional protocols before prescribing or administering any medication. Dosing may vary based on patient-specific factors and clinical guidelines.
