Pharmacology. Norepinephrine is an endogenous catecholamine that stimulates mainly alpha-adrenergic receptors. It is used primarily as a vasopressor to increase systemic vascular resistance and venous return to the heart. Norepinephrine is also a weak beta1-adrenergic receptor agonist, and it may increase the heart rate and cardiac contractility in patients with shock. Norepinephrine is not effective orally and is absorbed erratically after subcutaneous injection. After intravenous administration, the onset of action is nearly immediate, and the duration of effect is 1–2 minutes after the infusion is discontinued.

Indications. Norepinephrine is used to increase blood pressure and cardiac output in patients with shock caused by venodilation, low systemic vascular resistance, or both. Hypovolemia, depressed myocardial contractility, hypothermia, and electrolyte imbalance should be corrected first or concurrently.

Contraindications

1. 
   

   Uncorrected hypovolemia.

   
   
2. 
   

   Norepinephrine is relatively contraindicated in patients who have peripheral arterial occlusive vascular disease with thrombosis or ergot poisoning (See Ergot Derivatives).

Adverse effects

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