#dobutrex

Common Brand Names: Dobutrex

Therapeutic Class: Adrenergic agonist

Common Injectable Dosage Forms:

Solution for Injection: 12.5 mg/mL in 20 mL, 40 mL, and 100 mL.

Premixed in Dextrose: 1 mg/mL (250 mL, 500 mL), 2 mg/mL (250 mL), and 4 mg/mL (250 mL)

Dosage Ranges:

Dobutamine is administered by slow IV infusion using an infusion pump or other device to strictly control the rate of flow. The concentrate for injection must be diluted before infusion to a maximum concentration of 5 mg/mL. Dobutamine infusions should be monitored by evaluating heart rate, blood pressure, urine output, cardiac output, and, if possible, central venous pressure. The normal response range for increasing cardiac output is 2.5-20 mcg/kg/minute with doses as high as 40 mcg/kg/minute in some cases. Rate and duration of dobutamine use should be adjusted according to monitoring parameters.

Administration and Stability: Reconstituted solution is stable for 48 hours refrigerated and 6 hours at room temperature. Admixture is stable at room temperature for 48 hours and 7 days refrigerated. Dobutamine should be administered into a large vein; avoid use of heparin in same IV line. pH 2.5-5.5

Pharmacology/Pharmacokinetics: The mechanism of dobutamine is somewhat complex but it is generally considered a selective beta 1-adrenergic agonist. The beta 1-adrenergic effects exert a positive inotropic effect on the myocardium and result in increased cardiac output accompanied by an increase in myocardial contractility and stroke volume. Following IV administration, dobutamine has an onset of action within 2 minutes. Peak plasma concentrations and effects occur within 10 minutes of the initiation of IV infusion. The drug’s effects cease shortly after discontinuation, but an IV infusion is usually weaned off over several hours.

Drug and Lab Interactions: Some of the cardiac effects of dobutamine may be antagonized by concurrent administration of beta-adrenergic blocking agents such as metoprolol and metoprolol.

Contraindications/Precautions: Patients with idiopathic hypertrophic subaortic stenosis are specifically contraindicated from dobutamine use. Any hypovolemia should be corrected before initiation of dobutamine therapy. Dobutamine may, in rare cases, cause hypokalemia. Pregnancy Category B.

Monitoring Parameters: Blood pressure, ECG, heart rate, CVP, RAP, MAP, urine output, serum potassium

Adverse Effects: The principal adverse effects of dobutamine include ectopic heartbeats, elevated heart rate, angina, chest pain, and elevations in blood pressure. Dobutamine may also cause large decreases in blood pressure, which in rare instances, may not be easily reversible by dosage reduction or discontinuation of the drug. Extravasation of dobutamine may lead to phlebitis and/or tissue necrosis. This reaction may be treated by local injection of phentolamine to help facilitate dispersing the drug.