Milrinone

INDICATIONS AND USAGE Milrinone Lactate Injection is indicated for the short-term intravenous treatment of patients with acute decompensated heart failure. Patients receiving milrinone lactate should be observed closely with appropriate electrocardiographic equipment. The facility for immediate treatment of potential cardiac events, which may include life threatening ventricular arrhythmias, must be available. The majority of experience with intravenous milrinone lactate has been in patients receiving digoxin and diuretics.

CLINICAL PHARMACOLOGY Milrinone lactate is a positive inotrope and vasodilator, with little chronotropic activity different in structure and mode of action from either the digitalis glycosides or catecholamines. Milrinone lactate, at relevant inotropic and vasorelaxant concentrations, is a selective inhibitor of peak III cAMP phosphodiesterase isozyme in cardiac and vascular muscle. This inhibitory action is consistent with cAMP mediated increases in intracellular ionized calcium and contractile force in cardiac muscle, as well as with cAMP dependent contractile protein phosphorylation and relaxation in vascular muscle. Additional experimental evidence also indicates that milrinone lactate is not a beta-adrenergic agonist nor does it inhibit sodium-potassium adenosine triphosphatase activity as do the digitalis glycosides. Clinical studies in patients with congestive heart failure have shown that milrinone lactate produces dose-related and plasma drug concentration-related increases in the maximum rate of increase of left ventricular pressure. Studies in normal subjects have shown that milrinone lactate produces increases in the slope of the left ventricular pressure-dimension relationship, indicating a direct inotropic effect of the drug. Milrinone lactate also produces dose-related and plasma concentration-related increases in forearm blood flow in patients with congestive heart failure, indicating a direct arterial vasodilator activity of the drug. Both the inotropic and vasodilatory effects have been observed over the therapeutic range of plasma milrinone concentrations of 100 ng/mL to 300 ng/mL. In addition to increasing myocardial contractility, milrinone lactate improves diastolic function as evidenced by improvements in left ventricular diastolic relaxation. The acute administration of intravenous milrinone has also been evaluated in clinical trials in excess of 1600 patients, with chronic heart failure, heart failure associated with cardiac surgery, and heart failure associated with myocardial infarction. The total number of deaths, either on therapy or shortly thereafter (24 hours) was 15, less than 0.9%, few of which were thought to be drug-related.

DOSAGE AND ADMINISTRATION Milrinone Lactate Injection, USP should be administered with a loading dose followed by a continuous infusion (maintenance dose) according to the following guidelines: LOADING DOSE 50 mcg/kg: Administer slowly over 10 minutes The table below shows the loading dose in milliliters (mL) of milrinone lactate (1mg/mL) by patient body weight (kg). Loading Dose (mL) Using 1 mg/mL Concentration Patient Body Weight (kg) kg 30 40 50 60 70 80 90 100 110 120 mL 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 The loading dose may be given undiluted, but diluting to a rounded total volume of 10 or 20 mL (see Maintenance Dose for diluents) may simplify the visualization of the injection rate. MAINTENANCE DOSE Infusion Rate Total Daily Dose (24 Hours) Minimum 0.375 mcg/kg/min 0.59 mg/kg Administer as a continuous intravenous infusion Standard 0.5 mcg/kg/min 0.77 mg/kg Maximum 0.75 mcg/kg/min 1.13 mg/kg Milrinone lactate drawn from vials should be diluted prior to maintenance dose administration. The diluents that may be used are 0.45% Sodium Chloride Injection USP, 0.9% Sodium Chloride Injection USP, or 5% Dextrose Injection USP. The table below shows the volume of diluent in milliliters (mL) that must be used to achieve 200 mcg/mL concentration for infusion, and the resultant total volumes. Desired Infusion Concentration mcg/mL Milrinone Lactate Injection 1 mg/mL (mL) Diluent (mL) Total Volume (mL) 200 10 40 50 200 20 80 100 The infusion rate should be adjusted according to hemodynamic and clinical response. Patients should be closely monitored. In controlled clinical studies, most patients showed an improvement in hemodynamic status as evidenced by increases in cardiac output and reductions in pulmonary capillary wedge pressure. Note: See Dosage Adjustment in Renally Impaired Patients . Dosage may be titrated to the maximum hemodynamic effect and should not exceed 1.13 mg/kg/day. Duration of therapy should depend upon patient responsiveness. The maintenance dose in mL/hr by patient body weight (kg) may be determined by reference to the following table. Milrinone Infusion Rate (mL/hr) Using 200 mcg/mL Concentration Maintenance Dose (mcg/kg/min) Patient Body Weight (kg) 30 40 50 60 70 80 90 100 110 120 0.375 3.4 4.5 5.6 6.8 7.9 9 10.1 11.3 12.4 13.5 0.4 3.6 4.8 6 7.2 8.4 9.6 10.8 12 13.2 14.4 0.5 4.5 6 7.5 9 10.5 12 13.5 15 16.5 18 0.6 5.4 7.2 9 10.8 12.6 14.4 16.2 18 19.8 21.6 0.7 6.3 8.4 10.5 12.6 14.7 16.8 18.9 21 23.1 25.2 0.75 6.8 9 11.3 13.5 15.8 18 20.3 22.5 24.8 27 When administering milrinone lactate by continuous infusion, it is advisable to use a calibrated electronic infusion device. Intravenous drug products should be inspected visually and should not be used if particulate matter or discoloration is present. Dosage Adjustment in Renally Impaired Patients Data obtained from patients with severe renal impairment (creatinine clearance = 0 to 30 mL/min) but without congestive heart failure have demonstrated that the presence of renal impairment significantly increases the terminal elimination half-life of milrinone lactate. Reductions in infusion rate may be necessary in patients with renal impairment. For patients with clinical evidence of renal impairment, the recommended infusion rate can be obtained from the following table: Creatinine Clearance (mL/min/1.73m 2 ) Infusion Rate (mcg/kg/min) 5 0.2 10 0.23 20 0.28 30 0.33 40 0.38 50 0.43

ADVERSE REACTIONS Cardiovascular Effects In patients receiving milrinone lactate in Phase II and III clinical trials, ventricular arrhythmias were reported in 12.1%: Ventricular ectopic activity, 8.5%; nonsustained ventricular tachycardia, 2.8%; sustained ventricular tachycardia, 1% and ventricular fibrillation, 0.2% (2 patients experienced more than one type of arrhythmia). Holter recordings demonstrated that in some patients injection of milrinone lactate increased ventricular ectopy, including nonsustained ventricular tachycardia. Life-threatening arrhythmias were infrequent and when present have been associated with certain underlying factors such as preexisting arrhythmias, metabolic abnormalities (e.g. hypokalemia), abnormal digoxin levels and catheter insertion. Milrinone lactate was not shown to be arrhythmogenic in an electrophysiology study. Supraventricular arrhythmias were reported in 3.8% of the patients receiving milrinone lactate. The incidence of both supraventricular and ventricular arrhythmias has not been related to the dose or plasma milrinone concentration. Other cardiovascular adverse reactions include hypotension, 2.9% and angina/chest pain, 1.2%. In the post marketing experience, there have been rare cases of “torsades de pointes” reported. CNS Effects Headaches, usually mild to moderate in severity, have been reported in 2.9% of patients receiving milrinone lactate. Other Effects Other adverse reactions reported, but not definitely related to the administration of milrinone lactate include hypokalemia, 0.6%; tremor, 0.4%; and thrombocytopenia, 0.4%. Isolated spontaneous reports of bronchospasm and anaphylactic shock have been received; and in the post-marketing experience, liver function test abnormalities and skin reactions such as rash have been reported. Post-Marketing Adverse Event Reports In addition to adverse events reported from clinical trials, the following events have been reported from worldwide post-marketing experience with milrinone: Isolated spontaneous reports of bronchospasm and anaphylactic shock. Liver function test abnormalities and skin reactions such as rash. Administration site conditions: Infusion site reaction. To report SUSPECTED ADVERSE REACTIONS, contact Mullan Pharmaceutical Inc., at 1-800-673-9839 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

WARNINGS Whether given orally or by continuous or intermittent intravenous infusion, milrinone lactate has not been shown to be safe or effective in the longer (greater than 48 hours) treatment of patients with heart failure. In a multicenter trial of 1088 patients with Class III and IV heart failure, long-term oral treatment with milrinone lactate was associated with no improvement in symptoms and an increased risk of hospitalization and death. In this study, patients with Class IV symptoms appeared to be at particular risk of life-threatening cardiovascular reactions. There is no evidence that milrinone lactate given by long-term continuous or intermittent infusion does not carry a similar risk. The use of milrinone lactate both intravenously and orally has been associated with increased frequency of ventricular arrhythmias, including nonsustained ventricular tachycardia. Long-term oral use has been associated with an increased risk of sudden death. Hence, patients receiving milrinone lactate should be observed closely with the use of continuous electrocardiographic monitoring to allow the prompt detection and management of ventricular arrhythmias.

CONTRAINDICATIONS Milrinone Lactate Injection is contraindicated in patients who are hypersensitive to it.

OVERDOSAGE Doses of milrinone lactate may produce hypotension because of its vasodilator effect. If this occurs, administration of milrinone lactate should be reduced or temporarily discontinued until the patient’s condition stabilizes. No specific antidote is known, but general measures for circulatory support should be taken.