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# Norepinephrine
## Overview
Norepinephrine is a potent sympathomimetic amine that acts as a vasopressor. It primarily stimulates alpha-adrenergic receptors, causing vasoconstriction and increasing systemic vascular resistance and blood pressure. It also has some beta-1 adrenergic activity, which can increase myocardial contractility.
## Primary Indications
* Treatment of severe hypotension and shock, particularly septic shock and cardiogenic shock, unresponsive to adequate fluid resuscitation.
## Adult Dosing
* **Loading Dose:** Not typically given.
* **Maintenance Dose:** Initiate as a continuous intravenous infusion.
* Usual starting dose: 0.01 to 0.02 mcg/kg/min.
* Titrate based on blood pressure response.
* Maximum dose: Generally considered 0.2 to 1 mcg/kg/min, but doses up to 3 mcg/kg/min may be used in refractory hypotension under expert guidance.
* **Dose adjustment will depend on individual patient response and local protocol.**
## Pediatric Dosing
* **Loading Dose:** Not typically given.
* **Maintenance Dose:** Initiate as a continuous intravenous infusion.
* Usual starting dose: 0.05 to 0.1 mcg/kg/min.
* Titrate based on blood pressure response.
* Maximum dose: Generally considered 2 mcg/kg/min, but higher doses may be used in specific circumstances.
* **Dose adjustment will depend on individual patient response and local protocol.**
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment is typically recommended, but caution is advised as drug clearance may be reduced.
* **Hepatic Impairment:** No specific dose adjustment is typically recommended, but caution is advised as drug clearance may be reduced.
* **Elderly:** No specific dose adjustment is typically recommended, but they may be more sensitive to its effects.
## Contraindications
* Hypersensitivity to norepinephrine or any component of the formulation.
* Severe hypotension due to relative hypovolemia (unless used as a temporizing measure during volume resuscitation).
* Tachyarrhythmias.
## Adverse Effects
* **Cardiovascular:** Hypertension, reflex bradycardia, arrhythmias (tachycardia, ventricular extrasystoles), peripheral ischemia, digital ischemia, myocardial infarction, stroke.
* **Extravasation:** Severe tissue necrosis, sloughing, and gangrene. If extravasation occurs, stop the infusion, do not remove the IV catheter, and attempt to infiltrate the affected area with phentolamine (an alpha-adrenergic blocker).
* **Other:** Headache, anxiety, tremor, dizziness, dyspnea, nausea, vomiting.
## Key Drug Interactions
* **General Anesthetics:** May potentiate hypertensive and arrhythmogenic effects. Use with extreme caution.
* **Beta-Adrenergic Blockers:** May lead to unopposed alpha-adrenergic stimulation, resulting in severe hypertension.
* **MAO Inhibitors and Tricyclic Antidepressants:** May prolong and intensify the pressor effects of norepinephrine. Avoid use; if unavoidable, use with extreme caution and significantly reduced doses.
* **Alpha-Adrenergic Blockers:** May antagonize the pressor effects of norepinephrine.
* **Oxytocic Drugs:** May cause severe hypertension.
## Monitoring
* Continuous blood pressure monitoring (arterial line preferred).
* Heart rate and rhythm.
* Urine output.
* Peripheral perfusion (e.g., skin temperature, color, capillary refill).
* Central venous pressure and pulmonary artery pressures (if monitored).
* Infusion site for signs of extravasation.
## Clinical Pearls
* Norepinephrine should be administered via a central venous catheter whenever possible to minimize the risk of extravasation and tissue necrosis.
* Always ensure adequate intravascular volume status before initiating or escalating norepinephrine infusions.
* Norepinephrine should be infused through a dedicated line or with a Y-connector proximal to the intended infusion site, as it is incompatible with alkaline solutions.
* Use the lowest effective dose for the shortest possible duration to minimize adverse effects.
* Withdraw the infusion gradually when discontinuing to prevent sudden hypotension.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines for complete details and before making any treatment decisions.*
