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# Norepinephrine
## Overview
Norepinephrine is a potent alpha-1 adrenergic agonist with some beta-1 adrenergic agonist activity. It primarily causes vasoconstriction, leading to increased systemic vascular resistance and blood pressure.
## Primary Indications
* Treatment of hypotension in shock states, including septic shock, neurogenic shock, and cardiogenic shock.
## Adult Dosing
* **Initial:** 2 to 10 mcg/minute via continuous intravenous infusion.
* **Titration:** Increase dose by 2 to 10 mcg/minute every 2 to 5 minutes based on patient's blood pressure response (target systolic blood pressure typically 80-100 mmHg or mean arterial pressure [MAP] 65-75 mmHg, depending on protocol).
* **Maximum:** Doses may exceed 30 mcg/minute in some cases, but higher doses are associated with increased risk of adverse effects.
## Pediatric Dosing
* **Initial:** 0.05 to 0.1 mcg/kg/minute via continuous intravenous infusion.
* **Titration:** Increase dose by 0.05 to 0.2 mcg/kg/minute every 5 to 10 minutes based on hemodynamic response.
* **Maximum:** Typically 1 to 2 mcg/kg/minute, but may be higher in specific refractory cases. Dosing is highly protocol-dependent.
## Dose Adjustments
* **Renal Impairment:** No specific adjustment recommended, but prolonged use or higher doses may require closer monitoring.
* **Hepatic Impairment:** No specific adjustment recommended.
## Contraindications
* Hypersensitivity to norepinephrine.
* Hypotension due to pure hypovolemia (unless used temporarily while volume resuscitation is underway).
* Use during cyclopropane and halothane anesthesia (risk of severe hypertension and arrhythmias).
## Adverse Effects
* **Cardiovascular:** Hypertension, reflex bradycardia, arrhythmias, peripheral ischemia, extravasation leading to tissue necrosis, angina.
* **CNS:** Headache, anxiety, dizziness.
* **Metabolic:** Hyperglycemia.
## Key Drug Interactions
* **MAO Inhibitors & Tricyclic Antidepressants:** Potentiate hypertensive crisis. Discontinue MAOIs at least 14 days prior to norepinephrine administration.
* **Beta-Blockers:** Can unmask unopposed alpha-adrenergic effects, leading to severe hypertension.
* **Ergot Alkaloids & Oxytocics:** May cause severe, prolonged hypertension.
* **General Anesthetics:** Increased risk of arrhythmias.
## Monitoring
* Continuous blood pressure monitoring (intra-arterial line preferred for accurate titration).
* Heart rate and rhythm.
* Urine output.
* Central venous pressure (CVP) and pulmonary artery pressures (if available).
* Assess peripheral perfusion and signs of extravasation.
* Serum glucose levels.
## Clinical Pearls
* Norepinephrine is a potent vasopressor that should be administered via a central venous catheter to minimize the risk of extravasation and tissue necrosis.
* In case of extravasation, discontinue infusion immediately and infiltrate the area with phentolamine.
* Titrate to the lowest effective dose to achieve hemodynamic goals and minimize adverse effects.
* Ensure adequate intravascular volume is established before or concurrently with norepinephrine initiation.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols for complete details.*
