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# Norepinephrine
## Overview
Norepinephrine is a potent alpha-1 adrenergic agonist and a weaker beta-1 adrenergic agonist. Its primary effect is peripheral vasoconstriction, leading to increased systemic vascular resistance and blood pressure. It also has a modest inotropic effect on the heart.
## Primary Indications
* Treatment of hypotension and shock (e.g., septic shock, cardiogenic shock, neurogenic shock).
* Restoration of blood pressure in patients with severe, life-threatening hypotension.
## Adult Dosing
* **Initial Dose:** 2 to 10 mcg/minute IV infusion.
* **Titration:** Titrate infusion rate based on patient's hemodynamic response (blood pressure, heart rate, signs of end-organ perfusion).
* **Maximum Dose:** Doses as high as 30 mcg/minute or more may be required in severe shock states, but efficacy and safety at very high doses are less established. Local protocol often guides maximum titration.
## Pediatric Dosing
* **Initial Dose:** 0.05 to 0.1 mcg/kg/minute IV infusion.
* **Titration:** Titrate infusion rate based on patient's hemodynamic response. Doses up to 1 mcg/kg/minute may be necessary. Local protocol is essential for pediatric dosing.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment is typically recommended, but close monitoring of response and potential for accumulation is important.
* **Hepatic Impairment:** No specific dose adjustment is typically recommended, but close monitoring of response is important.
## Contraindications
* Hypersensitivity to norepinephrine.
* Severe hypotension with hypoperfusion secondary to peripheral arterial vasodilation (e.g., distributive shock).
## Adverse Effects
* **Common:** Hypertension, bradycardia (reflex), headache, peripheral ischemia, arrhythmias, anxiety, dizziness, decreased cardiac output.
* **Serious:** Extravasation leading to tissue necrosis, myocardial infarction, CVA, severe hypertension, pulmonary edema, cardiac arrest.
## Key Drug Interactions
* **Monoamine Oxidase Inhibitors (MAOIs):** Potentiated hypertensive response. Avoid concurrent use or use with extreme caution and reduced doses.
* **Tricyclic Antidepressants (TCAs):** Potentiated hypertensive response. Use with caution.
* **Beta-blockers:** May antagonize the beta-1 effects of norepinephrine, leading to unopposed alpha-1 stimulation and severe hypertension.
* **General Anesthetics:** May increase myocardial irritability and risk of arrhythmias.
* **Ergot alkaloids:** Potentiated vasoconstrictive effects.
## Monitoring
* Continuous arterial blood pressure monitoring.
* Heart rate and rhythm.
* Central venous pressure (if available).
* Urine output.
* Signs of peripheral perfusion (skin color, temperature, capillary refill).
* Signs of extravasation.
* Electrolytes, acid-base status.
## Clinical Pearls
* Administer via a central venous catheter to minimize risk of extravasation and tissue necrosis.
* If extravasation occurs, discontinue infusion and infiltrate the affected area with phentolamine mesylate.
* Norepinephrine has a short half-life; infusion should not be abruptly stopped. Taper gradually.
* Use in conjunction with adequate fluid resuscitation. Norepinephrine is not a substitute for volume replacement.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information, institutional protocols, and available literature for complete and up-to-date guidance before making clinical decisions.
