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# Norepinephrine ## Overview Norepinephrine is a non-selective catecholamine with potent alpha-1 adrenergic activity (vasoconstriction) and moderate beta-1 adrenergic activity (inotropy). It is the first-line vasopressor for septic shock. ## Primary Indications * Acute hypotensive states (e.g., septic shock, cardiogenic shock). * Hemodynamic support during cardiac arrest (post-return of spontaneous circulation). ## Adult Dosing * **Initial:** 0.05 to 0.1 mcg/kg/min (or 2–4 mcg/min) via continuous IV infusion. * **Titration:** Titrate by 0.05–0.1 mcg/kg/min every 3–5 minutes to achieve target mean arterial pressure (MAP) (typically >65 mmHg). * **Maintenance:** Generally 0.01 to 3 mcg/kg/min. * *Note: Dosing is highly protocol-dependent; verify local institutional guidelines.* ## Pediatric Dosing * **Initial:** 0.05 to 0.1 mcg/kg/min continuous IV infusion. * **Titration:** Increase by 0.05 mcg/kg/min every 5–15 minutes as needed. * **Maximum:** Up to 1–2 mcg/kg/min in severe refractory shock. ## Dose Adjustments * **Renal/Hepatic Impairment:** No specific adjustment required; use with caution due to sensitivity to vasoconstriction. * **Weaning:** Wean gradually to prevent rebound hypotension. ## Contraindications * Hypersensitivity to norepinephrine or bisulfites. * Hypotension due to uncorrected hypovolemia (must restore circulating volume first). ## Adverse Effects * **Cardiovascular:** Bradycardia (reflex), arrhythmias, hypertension, peripheral ischemia. * **Local:** Extravasation can cause severe tissue necrosis and sloughing (treat with phentolamine infiltration if extravasation occurs). * **Metabolic:** Hyperglycemia, lactic acidosis (at prolonged high doses). ## Key Drug Interactions * **MAO Inhibitors/Tricyclic Antidepressants:** May cause severe, prolonged hypertension. * **Beta-Blockers:** May cause excessive peripheral vasoconstriction and reflex bradycardia (unopposed alpha-stimulation). * **Halogenated Hydrocarbons (e.g., Cyclopropane, Halothane):** Increase myocardial sensitivity to catecholamines, increasing arrhythmia risk. ## Monitoring * Continuous blood pressure (arterial line preferred for titration). * Heart rate and rhythm (ECG). * Mean Arterial Pressure (MAP). * Peripheral perfusion (site of infusion—inspect for extravasation). * Urine output. * Serum lactate and acid-base status. ## Clinical Pearls * **Central Line Requirement:** Preferentially administered via a central line to prevent severe tissue necrosis from extravasation, though peripheral administration is acceptable in emergencies for short durations through a large-bore proximal vein. * **Fluid Status:** Norepinephrine is ineffective in the setting of severe hypovolemia; ensure adequate fluid resuscitation prior to or concomitant with initiation. * **Dilution:** Must be diluted (usually in D5W or NS) before administration. Ensure concentration is standardized per institutional policy to prevent medication errors. *** *Disclaimer: This information is for educational purposes only. Clinical practice guidelines change frequently. Always verify specific dosing, safety warnings, and institutional protocols with current official product monographs and clinical drug databases before prescribing or administering medication.*