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# Norepinephrine ## Overview Norepinephrine is a sympathomimetic amine that acts as a vasopressor and cardiac stimulant. It primarily acts on alpha-1 adrenergic receptors causing vasoconstriction, and to a lesser extent on beta-1 adrenergic receptors increasing heart rate and contractility. ## Primary Indications * Treatment of hypotension, particularly in shock states (e.g., septic shock, cardiogenic shock). * Restoration and maintenance of blood pressure. ## Adult Dosing * **Initial Infusion:** 0.01 to 0.02 mcg/kg/min IV. * **Titration:** Increase infusion rate by 0.005 to 0.01 mcg/kg/min every 5-15 minutes until target blood pressure is achieved. * **Maximum Dose:** Generally, up to 0.3 mcg/kg/min IV, though higher doses may be used in select refractory cases under expert guidance. * *Dosing is highly individualized and titrations are guided by hemodynamic response.* ## Pediatric Dosing * **Initial Infusion:** 0.05 to 0.1 mcg/kg/min IV. * **Titration:** Increase infusion rate by 0.05 to 0.2 mcg/kg/min every 5-15 minutes until target blood pressure is achieved. * **Maximum Dose:** Generally, up to 1 mcg/kg/min IV. Some sources suggest higher doses may be necessary but should be used cautiously. * *Dosing is highly individualized and titrations are guided by hemodynamic response; expert consultation is recommended.* ## Dose Adjustments * No dose adjustments are typically needed for hepatic or renal impairment. However, underlying conditions contributing to shock may require dose adjustments. ## Contraindications * Hypersensitivity to norepinephrine. * Use during general anesthesia with cyclopropane or halogenated hydrocarbons due to risk of severe hypertension and arrhythmias. ## Adverse Effects * **Cardiovascular:** Hypertension, bradycardia (reflex), arrhythmias, peripheral ischemia, myocardial infarction, extravasation leading to tissue necrosis. * **Central Nervous System:** Headache, anxiety, tremor, dizziness. * **Other:** Dyspnea, nausea, vomiting. ## Key Drug Interactions * **MAO Inhibitors & TCAs:** Potentiate hypertensive effects. Avoid concurrent use or use with extreme caution and reduced doses. * **Beta-Blockers:** May block the cardiac stimulant effects of norepinephrine and enhance unopposed alpha-adrenergic effects, potentially leading to severe hypertension. * **Alpha-Blockers:** May antagonize vasoconstrictive effects. ## Monitoring * Continuous blood pressure monitoring (arterial line preferred). * Heart rate and rhythm. * Central venous pressure (CVP). * Urine output. * Signs of peripheral perfusion (e.g., skin color, temperature, capillary refill). * 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. * If extravasation occurs, discontinue infusion immediately and infiltrate the area with phentolamine. * Rapid infusions can lead to acute hypertension. * Norepinephrine is light-sensitive and should be protected from light. *** Please verify the current prescribing information and institutional protocols for specific patient management. This information is for educational purposes and does not replace professional clinical judgment.