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# Norepinephrine
## Overview
Norepinephrine is a potent vasopressor and inotropic agent that acts primarily on alpha-1 adrenergic receptors, causing vasoconstriction, and to a lesser extent on beta-1 adrenergic receptors, increasing heart rate and contractility.
## Primary Indications
* Severe hypotension, particularly in shock states (e.g., septic shock, cardiogenic shock).
* Restoration and maintenance of blood pressure.
## Adult Dosing
* **Typical dose:** 2 to 12 mcg/minute IV infusion.
* **Titration:** Titrate to achieve target mean arterial pressure (MAP), often 65 mmHg or higher.
* **Maximum dose:** Doses up to 30 mcg/minute have been used in severe refractory hypotension, but higher doses are associated with increased risk of adverse events. Dosing is highly individualized and protocol-dependent.
## Pediatric Dosing
* **Loading dose:** 0.05 to 0.2 mcg/kg/minute IV infusion.
* **Maintenance dose:** 0.01 to 2 mcg/kg/minute IV infusion.
* **Titration:** Titrate to achieve target blood pressure (e.g., systolic BP > 70 mmHg plus 2 times age in years). Dosing is highly individualized and protocol-dependent.
## Dose Adjustments
* No specific dose adjustments are required for hepatic or renal impairment, as norepinephrine is metabolized extraneously. However, close monitoring of hemodynamic response is crucial in these populations.
## Contraindications
* Hypersensitivity to norepinephrine.
* Use during general anesthesia with cyclopropane or halogenated hydrocarbons (may cause severe hypertension or arrhythmias).
* Tachyarrhythmias or ventricular fibrillation.
## Adverse Effects
* **Cardiovascular:** Hypertension, bradycardia (reflex), tachycardia, arrhythmias, peripheral ischemia, necrosis (extravasation), decreased blood flow to vital organs.
* **Other:** Headache, anxiety, tremors, dizziness.
## Key Drug Interactions
* **Monoamine Oxidase Inhibitors (MAOIs) & Tricyclic Antidepressants (TCAs):** Potentiate hypertensive effects. Discontinue MAOIs at least 14 days prior to norepinephrine. Use with extreme caution if concurrent use is unavoidable.
* **General Anesthetics (volatile):** Increased risk of arrhythmias.
* **Beta-blockers:** May cause unopposed alpha-stimulation, leading to severe hypertension.
* **Alpha-blockers:** May reduce pressor effects.
* **Ergot alkaloids & Oxytocic agents:** May cause severe sustained hypertension.
## Monitoring
* **Hemodynamics:** Continuous ECG monitoring, frequent blood pressure monitoring (arterial line preferred), heart rate, cardiac output (if available).
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