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# Norepinephrine ## Overview Norepinephrine is a potent catecholamine with alpha-1 agonist properties (vasoconstriction) and beta-1 agonist properties (inotropic support). It is the first-line vasopressor for septic shock. ## Primary Indications * Acute hypotensive states and shock (e.g., septic, cardiogenic, neurogenic). * Adjunct treatment during cardiac arrest when hemodynamic support is required post-resuscitation. ## Adult Dosing * **Initial:** 0.01–0.05 mcg/kg/min via continuous IV infusion. * **Titration:** Titrate by 0.01–0.05 mcg/kg/min every 2–5 minutes to achieve target mean arterial pressure (MAP, usually >65 mmHg). * **Maintenance:** Usual range 0.05–0.5 mcg/kg/min. * **Refractory Shock:** Doses exceeding 1 mcg/kg/min are occasionally used but carry significant risk of end-organ ischemia. * *Note: Dosing depends heavily on local institutional ICU protocols.* ## Pediatric Dosing * **Continuous IV Infusion:** 0.05–0.1 mcg/kg/min initial. * **Titration:** Titrate as needed to maintain adequate perfusion pressure. Usual therapeutic range corresponds to adult requirements; monitor for tachycardia and profound vasoconstriction. ## Dose Adjustments * **Hepatic/Renal Impairment:** No formal adjustment guidelines; metabolic clearance is rapid (via COMT and MAO). * **Extravasation Risk:** Must be administered via a large peripheral vein (for very short term) or dedicated central venous catheter. If extravasation occurs, phentolamine infiltration is indicated to prevent tissue necrosis. ## Contraindications * Hypersensitivity to norepinephrine or sulfites. * Hypotension due to uncorrected blood volume depletion (except as an emergency measure). * Mesenteric or peripheral vascular thrombosis (risk of worsening ischemia). ## Adverse Effects * **Cardiovascular:** Hypertension, arrhythmias (bradycardia or tachycardia), myocardial ischemia. * **Extremities:** Peripheral ischemia, skin necrosis, gangrene. * **Other:** Metabolic acidosis, anxiety, headache. ## Key Drug Interactions * **MAO Inhibitors / TCAs:** May produce severe, prolonged hypertension. * **Beta-blockers:** May cause excessive bradycardia and unopposed alpha-mediated vasoconstriction. * **Halogenated Hydrocarbons (e.g., volatile anesthetics):** May sensitize the myocardium to arrhythmias. ## Monitoring * **Invasive:** Continuous arterial blood pressure monitoring is strongly recommended. * **Cardiovascular:** EKG for rhythm assessment, heart rate, and perfusion status (capillary refill, lactate, urine output). * **Site:** Hourly assessment of IV site for signs of infiltration or extravasation. ## Clinical Pearls * **Volume Status:** Norepinephrine should not be used as a substitute for volume resuscitation in hypovolemic patients. * **"Leads to Dead":** Peripheral administration should be avoided for prolonged periods; if used peripherally, ensure a dilute concentration and a large, proximal vein to reduce necrotic complications. * **Discontinuation:** Always taper gradually to prevent rebound hypotension. *** *Disclaimer: This information is for educational purposes only. Dosing, preparation, and administration protocols vary by institution. Always consult your current facility-specific formulary, local clinical guidelines, and the official manufacturer's prescribing information before ordering or administering medication.*