#levophed

Common Brand Names: Levophed

Therapeutic Class: An endogenous catecholamine with vasopressor properties

Common Injectable Dosage Forms:

Solution for Injection: 1 mg/mL in 4 mL ampules

Dosage Ranges:

The average adult dosage is 8-12 mcg/minute with initiation at 0.5-1 mcg/minute titrated to response. Some refractory cases of shock may require 8-30 mcg/minute. Blood pressure should be taken every 2 minutes initially, then every 5 minutes until desired rate and response is obtained. Pressures in normotensive patients should be maintained at 80-100 mmHg, and 30-40 mmHg below previous levels in hypertensive patients.

The usual pediatric dose is 2 mcg/minute, or alternatively, 2 mcg/m2/minute.

Administration and Stability: Administer into large vein; norepinephrine is a potent drug that must be diluted prior to administration (D5W or D5NS, not NS) and administered via infusion pump. Parenteral admixture is stable 24 hours at room temperature and must be protected from light. Do not use if solution is brown.

Pharmacology/Pharmacokinetics: Norepinephrine directly stimulates alpha-adrenergic receptors and also stimulates beta-1-adrenergic receptors in the heart resulting in vasoconstriction and cardiac stimulation. Onset of action occurs virtually immediately with pressor action stopping within 1-2 minutes after discontinuation of the infusion. The drug localizes mainly in sympathetic nerve tissue, and its action is terminated by uptake and metabolism at these sites. The drug is metabolized by the liver and other sites with excretion of the metabolites via the urine.

Drug and Lab Interactions: Concomitant use of cyclopropane or halogenated hydrocarbon general anesthetics with norepinephrine may result in cardiac arrhythmias. Atropine enhances the pressor response to norepinephrine. Drugs such as tricyclic antidepressants, some antihistamines, guanethidine, ergot alkaloids, and methyldopa may potentiate pressor effects of this drug.

Contraindications/Precautions: Contraindicated in patients with profound hypoxia, hypercapnia, or receiving previously stated general anesthetics. Caution should be exercised in patients with hypovolemia and hyperthyroid patients. Extravasation at infusion sites may cause tissue sloughing, necrosis, and thrombophlebitis. Corrective measures including administration of phentolamine at the extravasation site should be instituted if this occurs. Pregnancy Category C.

Monitoring Parameters: Lab monitoring not necessary; monitor patient vital signs and for signs of toxicity.

Adverse Effects: Potentially dangerous effects with use include edema, decreased cardiac output, and plasma volume reduction. Other adverse effects include headache, tremors, restlessness, reduced renal blood flow, and cardiac arrhythmias.