#primacor

Common Brand Names: Primacor

Therapeutic Class: An inotropic/vasodilator agent

Common Injectable Dosage Forms:

Injection Vials: 1 mg/mL milrinone (as lactate) in 10 mL, 20 mL, and 50 mL single-dose vials.

Premix Flexible Containers: 200 mcg/mL milrinone (as lactate) in 100 mL and 200 mL ready to use dilutions in 5% Dextrose Injection.

Dosage Ranges:

For the short-term treatment of patients with acute decompensated heart failure:

Loading Dose: 50 mcg/kg given slowly over 10 minutes.

Maintenance Dose: 0.59-1.13 mg/kg/day or 0.375-0.75 mcg/kg/minute as a continuous intravenous infusion for up to 48 hours. Patients receiving milrinone should be observed closely with appropriate electrocardiographic equipment and be administered in a facility equipped to treat potential cardiac events, including life-threatening ventricular arrhythmias.

Maintenance doses with impaired renal function (creatinine clearance:infusion rate):

5-9 mL/min/1.73 m2: 0.20 mcg/kg/minute

10-10 mL/min/1.73 m2: 0.23 mcg/kg/minute

20-29 mL/min/1.73 m2: 0.28 mcg/kg/minute

30-39 mL/min/1.73 m2: 0.33 mcg/kg/minute

40-49 mL/min/1.73 m2: 0.38 mcg/kg/minute

50-59 mL/min/1.73 m2: 0.43 mcg/kg/minute

Administration and Stability: The loading dose may be given undiluted or diluted to a volume of 10-20 mL. The maintenance dose should be diluted prior to administration. Compatible diluents include 0.45% Sodium Chloride Injection, USP; 0.9% Sodium Chloride Injection, USP; or 5% Dextrose Injection, USP. The final diluted concentration should be 200 mcg/mL milrinone (1-part milrinone to 4 parts diluent). Should be stored at controlled room temperature. pH 3.2-4

Pharmacology/Pharmacokinetics: Milrinone is a bipyridine inotropic/vasodilator agent. Its mechanism of action is thought to be due to selective inhibition of peak III cAMP phosphodiesterase isoenzyme in cardiac and vascular muscle. This action results in an increase in intracellular ionized calcium and contractile force in cardiac muscle and with cAMP dependent contractile protein phosphorylation and relaxation in vascular muscle. The net result is an increase in the maximum rate of increase of left ventricular pressure and direct arterial vasodilation. Elimination occurs mainly as unchanged drug in the urine with a terminal elimination half-life of 2.4 hours.

Drug and Lab Interactions: There are no known drug interactions. A precipitate is formed when furosemide is injected into an intravenous line of an infusion of Primacor.

Contraindications/Precautions: Contraindicated in patients with known hypersensitivity to milrinone. Use has been associated with increased frequency of ventricular arrhythmias, including non-sustained ventricular tachycardia. Patients should be observed closely with continuous electrocardiographic monitoring. Infusion rates should be slowed or stopped in patients experiencing excessive decreases in blood pressure. Fluid and electrolyte changes should be carefully monitored during therapy. Improved cardiac output and resulting diuresis may predispose patients to hypokalemia. Pregnancy Category C.

Monitoring Parameters: Cardiac monitor and blood pressure monitoring, serum potassium

Adverse Effects: Milrinone has been shown to cause ventricular arrhythmias, including ventricular tachycardia. Appropriate monitoring should be employed during use. Other adverse effects include hypotension, headache, angina/chest pain, hypokalemia, and thrombocytopenia.