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# Norepinephrine (Levophed)
## Overview
Norepinephrine is a sympathomimetic amine that acts as a vasopressor and inotrope. It primarily stimulates alpha-1 adrenergic receptors, causing vasoconstriction and increasing systemic vascular resistance and blood pressure. It also has some beta-1 adrenergic receptor activity, increasing cardiac contractility.
## Primary Indications
* Treatment of hypotension (low blood pressure) in shock, particularly septic shock and neurogenic shock.
## Adult Dosing
* **Initial Rate:** 0.01 to 0.02 mcg/kg/min via continuous intravenous infusion.
* **Titration:** Increase dose in increments of 0.005 to 0.01 mcg/kg/min every 10-15 minutes as needed to achieve target blood pressure (often systolic BP > 90 mmHg or Mean Arterial Pressure [MAP] > 65 mmHg, but target goals may vary by institution and patient condition).
* **Maximum Rate:** Generally considered 0.2 mcg/kg/min, though higher doses may be used in refractory cases under close monitoring.
## Pediatric Dosing
* **Initial Rate:** 0.05 to 0.1 mcg/kg/min via continuous intravenous infusion.
* **Titration:** Increase dose as needed to achieve target blood pressure.
* **Maximum Rate:** Generally considered 0.2 mcg/kg/min.
* *Note: Pediatric dosing can vary significantly by institution and specific clinical scenario. Consult local protocols.*
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment is typically required, but caution and close monitoring are warranted due to potential accumulation and prolonged effects.
* **Hepatic Impairment:** No specific dose adjustment is typically required, but caution and close monitoring are warranted.
## Contraindications
* Hypotension due to volume deficit (must be corrected with fluids first).
* Use with volatile inhalation anesthetics (e.g., halothane) may potentiate arrhythmias.
## Adverse Effects
* **Cardiovascular:** Hypertension, reflex bradycardia, arrhythmias, palpitations, peripheral ischemia, extravasation leading to tissue necrosis.
* **Central Nervous System:** Headache, anxiety, tremor.
* **Respiratory:** Dyspnea.
* **Other:** Piloerection, sweating.
## Key Drug Interactions
* **Monoamine Oxidase Inhibitors (MAOIs):** Potentiates the pressor response; avoid concurrent use or use extreme caution and significantly reduced doses if norepinephrine is initiated within 14 days of MAOI discontinuation.
* **Tricyclic Antidepressants (TCAs):** May potentiate the pressor response; use with caution.
* **Beta-blockers:** Can blunt the cardiac stimulant effects of norepinephrine and potentially lead to unopposed alpha-adrenergic stimulation, causing severe hypertension.
* **Alpha-blockers:** Can antagonize the vasoconstrictive effects.
* **Ergot alkaloids and oxytocin:** Can cause severe hypertension.
* **Diuretics:** May potentiate hypotension.
## Monitoring
* Continuous electrocardiogram (ECG) for arrhythmias.
* Frequent blood pressure monitoring (arterial line preferred for continuous monitoring).
* Central venous pressure (CVP) and/or pulmonary artery pressures (PAP) if available.
* Urine output.
* Peripheral circulation (skin temperature, color, capillary refill).
* Infusion site for signs of extravasation.
## Clinical Pearls
* Always administer norepinephrine via a central venous catheter whenever possible. If a peripheral IV must be used, dilute to a lower concentration and monitor the infusion site meticulously for extravasation.
* Phentolamine should be readily available for local infiltration to treat extravasation.
* Norepinephrine is light-sensitive and should be protected from light during administration.
* Gradually taper norepinephrine to avoid sudden drops in blood pressure. Discontinuation should be done slowly.
* The choice of target blood pressure (systolic or MAP) depends on the patient's underlying condition and institutional protocols.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and local institutional protocols before administering any medication.*
