Nor%2525252525252525252525252525252525252525252525252525252525252525252525252525252520epinephrine

# Norepinephrine ## Overview Norepinephrine is a potent alpha-adrenergic agonist with some beta-1 adrenergic activity. It primarily causes vasoconstriction, leading to increased systemic vascular resistance and blood pressure. It also increases myocardial contractility to a lesser extent. ## Primary Indications * Treatment of hypotension and shock, particularly septic shock and cardiogenic shock, when fluid resuscitation alone is insufficient. ## Adult Dosing * **Initial:** 0.01 to 0.02 mcg/kg/min intravenously (IV). * **Maintenance:** Titrate IV infusion to achieve target blood pressure (e.g., Mean Arterial Pressure [MAP] of 65 mmHg or higher). Doses typically range from 0.01 to 0.3 mcg/kg/min. * **Maximum:** Doses exceeding 1 mcg/kg/min are rarely needed and may be associated with increased risk. Specific maximums often depend on local protocols and patient response. ## Pediatric Dosing * **Initial:** 0.05 to 0.1 mcg/kg/min IV. * **Maintenance:** Titrate IV infusion to achieve target MAP or systemic blood pressure based on age (e.g., MAP greater than gestational age in weeks for neonates, or 50 mmHg for older children). Doses typically range from 0.05 to 1 mcg/kg/min. * **Maximum:** Doses exceeding 1 mcg/kg/min are rarely needed. Specific maximums often depend on local protocols and patient response. ## Dose Adjustments * **Renal Impairment:** No specific adjustment is typically recommended due to its metabolism. * **Hepatic Impairment:** No specific adjustment is typically recommended. * **Elderly:** No specific adjustment is typically recommended. ## Contraindications * Hypersensitivity to norepinephrine. * Hypotension due to pure hypovolemia (requires fluid resuscitation first). * Use of cyclopropane or halogenated hydrocarbon anesthetics, as they may sensitize the myocardium to the effects of catecholamines. ## Adverse Effects * **Cardiovascular:** Hypertension, bradycardia, arrhythmias, peripheral ischemia, vasoconstriction leading to tissue necrosis if extravasation occurs. * **Central Nervous System:** Headache, anxiety, tremor. * **Respiratory:** Dyspnea. * **Metabolic:** Hyperglycemia. ## Key Drug Interactions * **MAO Inhibitors & Tricyclic Antidepressants:** Can potentiate the pressor response; avoid concurrent use or use with extreme caution and reduced initial doses. * **Beta-blockers:** May blunt the beta-1 effects of norepinephrine, potentially leading to unopposed alpha-stimulation and severe peripheral vasoconstriction. * **Alpha-blockers:** May antagonize the vasoconstrictive effects. * **Oxytocic Agents:** May cause severe sustained hypertension. * **Ergot Alkaloids:** May cause severe hypertension and peripheral ischemia. ## Monitoring * Continuous electrocardiogram (ECG) and invasive hemodynamic monitoring (e.g., arterial line). * Central venous pressure (CVP) and pulmonary artery pressures (if available). * Urine output. * Blood pressure and heart rate. * Peripheral perfusion and signs of extravasation. * Electrolytes and glucose. ## Clinical Pearls * Norepinephrine should be administered via a central venous catheter to minimize the risk of extravasation and tissue necrosis. * If extravasation occurs, discontinue the infusion immediately, do not flush the line, and administer phentolamine subcutaneously to the affected area. * Norepinephrine is light-sensitive and should be protected from light during administration. * The infusion rate must be titrated to achieve the desired hemodynamic effect and should be tapered gradually when discontinuing. *** **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 guidelines before making clinical decisions.