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# Norepinephrine
## Overview
Norepinephrine is a potent catecholamine with primary alpha-1 adrenergic agonist activity (vasoconstriction) and secondary beta-1 adrenergic agonist activity (inotropic effect). It is the first-line vasopressor for septic shock.
## Primary Indications
* Acute hypotensive states (e.g., septic shock, cardiogenic shock).
* Adjunct treatment for cardiac arrest (post-return of spontaneous circulation).
## Adult Dosing
* **Initial:** 0.01 to 0.05 mcg/kg/min continuous IV infusion.
* **Titration:** Titrate by 0.01 to 0.05 mcg/kg/min every 2–5 minutes based on blood pressure response.
* **Common hemodynamic range:** 0.05 to 0.5 mcg/kg/min.
* **Maximum:** No standard hard maximum exists; doses exceeding 1–3 mcg/kg/min are considered very high and often refractory to salvage therapy.
* *Note: Always verify concentration (e.g., 4 mg/250 mL or 8 mg/250 mL) per local institutional protocol.*
## Pediatric Dosing
* **Initial:** 0.05 to 0.1 mcg/kg/min continuous IV infusion.
* **Titration:** Titrate to effect in increments of 0.05 mcg/kg/min.
* **Range:** 0.05 to 2 mcg/kg/min.
## Dose Adjustments
* **Hepatic/Renal Impairment:** No specific dosage adjustments provided in manufacturer labeling; monitor for hemodynamic stability.
* **Geriatric:** Use the lowest effective dose; start at the lower end of the dosing range due to potential sensitivity to cardiovascular effects.
## Contraindications
* Hypersensitivity to norepinephrine or any component of the formulation.
* Hypotension due to uncorrected blood volume deficit (except as an emergency measure to maintain coronary/cerebral perfusion until blood volume replacement is completed).
## Adverse Effects
* **Common:** Hypertension, headache, anxiety.
* **Serious:** Tissue necrosis (if extravasation occurs), arrhythmias (bradycardia or tachycardia), limb ischemia, mesenteric ischemia.
## Key Drug Interactions
* **MAO Inhibitors/Linezolid:** May lead to severe, prolonged hypertensive crisis.
* **Tricyclic Antidepressants:** May potentiate the pressor response.
* **Beta-Blockers (Non-selective):** May lead to unopposed alpha-mediated vasoconstriction and severe hypertension.
## Monitoring
* **Continuous ECG:** Monitor for arrhythmias.
* **Blood Pressure:** Continuous arterial line monitoring is preferred, especially at high doses or in peripheral lines.
* **Peripheral Perfusion:** Assess digits/extremities frequently for signs of ischemia.
* **Extravasation:** Monitor site continuously. If extravasation occurs, infiltrate the site with phentolamine (alpha-adrenergic antagonist) immediately.
## Clinical Pearls
* **Administration:** Central venous access is strongly preferred to reduce the risk of extravasation and potential tissue necrosis. If peripheral administration is necessary, use a large, proximal vein for no longer than 48 hours.
* **Compatibility:** Administer through a dedicated line if possible; norepinephrine is incompatible with many common IV medications (e.g., sodium bicarbonate, insulin).
* **Weaning:** When discontinuing, wean slowly to avoid rebound hypotension.
* **Fluid Status:** Norepinephrine is not a substitute for isotonic fluid resuscitation in hypovolemic patients.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical practice guidelines and drug concentrations vary significantly by institution. Always verify specific dosing, patient weight-based calculations, and compatibility with your local hospital protocol and official prescribing information before administration.
