Nor%25252525252525252525252525252525252525252525252525252525252520epinephrine

# Norepinephrine ## Overview Norepinephrine is a potent alpha-1 adrenergic agonist and a weaker beta-1 adrenergic agonist. It causes peripheral vasoconstriction, leading to increased systemic vascular resistance and blood pressure. ## Primary Indications * Treatment of hypotension and shock, particularly distributive shock (e.g., septic shock, neurogenic shock). * Adjunct in cardiac arrest. ## Adult Dosing * **Hypotension/Shock:** Intravenous infusion, typically initiated at **2 to 4 mcg/min**. Doses may be titrated upwards based on patient response (mean arterial pressure [MAP] goal). Usual effective doses range from **0.01 to 0.1 mcg/kg/min**. Maximum dose is generally **0.1 mcg/kg/min**, but higher doses may be used in refractory cases under expert guidance. Titration to achieve a target MAP (e.g., 65 mmHg) is common, but specific targets may vary by indication and local protocol. * **Cardiac Arrest:** **1 mcg/kg bolus** intravenously or intraosseously, followed by **0.1 mcg/kg/min** infusion if return of spontaneous circulation (ROSC) is achieved. Bolus can be repeated every 3-5 minutes. ## Pediatric Dosing * **Hypotension/Shock:** Intravenous infusion, typically initiated at **0.05 to 0.1 mcg/kg/min**. Titrate to desired hemodynamic effect. Usual range is **0.1 to 2 mcg/kg/min**. Maximum dose is generally **2 mcg/kg/min**, but higher doses may be used in refractory cases under expert guidance. Specific target MAPs should be individualized. * **Cardiac Arrest:** **0.01 mg/kg (10 mcg/kg) bolus** intravenously or intraosseously, followed by **0.1 to 1 mcg/kg/min** infusion if ROSC is achieved. Bolus can be repeated every 3-5 minutes. ## Dose Adjustments No specific dose adjustments are required for hepatic or renal impairment, as norepinephrine is rapidly metabolized. However, clinical response remains the primary driver of dosing. ## Contraindications * Hypersensitivity to norepinephrine. * Use during general anesthesia with cyclopropane or halogenated hydrocarbons (risk of severe hypertension and arrhythmias). * Thromboembolic diseases where compromised circulation may be aggravated. ## Adverse Effects * **Common:** Hypertension, bradycardia (reflex), peripheral ischemia, local tissue necrosis (if extravasation), headache, anxiety, tremor. * **Serious:** Cardiac arrhythmias, myocardial infarction, pulmonary edema, severe hypertension. ## Key Drug Interactions * **Monoamine Oxidase Inhibitors (MAOIs) & Tricyclic Antidepressants (TCAs):** Potentiate the pressor response; concurrent use is generally contraindicated or requires extreme caution and dose reduction. * **Alpha-adrenergic Blockers:** May reduce the pressor effect. * **Beta-adrenergic Blockers:** May reduce the cardiac effects. * **General Anesthetics (Halogenated):** Increased risk of arrhythmias. * **Ergot Alkaloids & Oxytocin:** May cause severe hypertension. ## Monitoring * Continuous electrocardiogram (ECG). * Continuous blood pressure monitoring (arterial line preferred for infusions). * Central venous pressure (CVP) and/or pulmonary artery pressures if available. * Urine output. * Peripheral perfusion (skin temperature, color, capillary refill). * Serum lactate. * Electrolytes and renal function. ## Clinical Pearls * Norepinephrine must be administered via a central venous catheter to minimize the risk of extravasation and local tissue necrosis. * If extravasation occurs, stop the infusion immediately, remove the catheter, and infiltrate the affected area with **phentolamine mesylate** (e.g., 5-10 mg in 10-15 mL saline) to counteract the vasoconstriction. * Avoid abrupt discontinuation; gradual tapering is recommended, especially with prolonged infusions. * Consider co-administration with other vasopressors or inotropes based on the specific type of shock and patient response. *** **Disclaimer:** This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions. Dosing and management can vary significantly based on individual patient factors and institutional protocols.