Milrinone Lactate in 5% Dextrose

INDICATIONS AND USAGE Milrinone Lactate in 5% Dextrose Injection is indicated for the short-term intravenous treatment of patients with acute decompensated heart failure. Patients receiving milrinone 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 has been in patients receiving digoxin and diuretics. There is no experience in controlled trials with infusions of milrinone for periods exceeding 48 hours.

DOSAGE AND ADMINISTRATION Milrinone Lactate in 5% Dextrose Injection 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 Note: Milrinone (200 mcg per mL) in Plastic Container is for intravenous infusion only. Dosage recommendations using a 1 mg per mL concentration of milrinone are included for informational purposes only. The table below shows the loading dose in milliliters (mL) of milrinone (1 mg/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 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 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 Standard Maximum 0.375 mcg/kg/min 0.50 mcg/kg/min 0.75 mcg/kg/min 0.59 mg/kg 0.77 mg/kg 1.13 mg/kg Administer as a continuous intravenous infusion 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 9.0 10.1 11.3 12.4 13.5 0.400 3.6 4.8 6.0 7.2 8.4 9.6 10.8 12.0 13.2 14.4 0.500 4.5 6.0 7.5 9.0 10.5 12.0 13.5 15.0 16.5 18.0 0.600 5.4 7.2 9.0 10.8 12.6 14.4 16.2 18.0 19.8 21.6 0.700 6.3 8.4 10.5 12.6 14.7 16.8 18.9 21.0 23.1 25.2 0.750 6.8 9.0 11.3 13.5 15.8 18.0 20.3 22.5 24.8 27.0 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. 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 0.20 10 0.23 20 0.28 30 0.33 40 0.38 50 0.43 Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Milrinone Lactate in 5% Dextrose Injection is a clear, colorless to pale yellow solution. DIRECTIONS FOR USE When administering Milrinone Lactate in 5% Dextrose Injection by continuous infusion, it is advisable to use a calibrated electronic infusion device. To open Tear at the notch and open the overwrap to remove solution container. Some opacity of the plastic due to moisture absorption during the sterilization process may be observed. This is normal and does not affect the solution quality or safety. The opacity will diminish gradually. After removing overwrap, check for minute leaks by squeezing inner bag firmly. If leaks are found, discard solution as sterility may be impaired. Preparation for Administration Visually inspect the container. If the administration port is damaged, detached, or not present, discard container as solution path sterility may be impaired. (Use aseptic technique) 1. Suspend container from eyelet support. 2. Remove top portion of twist off port at bottom of container. 3. Attach administration set. Refer to complete directions accompanying set. WARNING: DO NOT USE IN SERIES CONNECTIONS. Do not administer simultaneously with blood. Caution: Do not use plastic containers in series connections. Such use could result in air embolism due to residual air being drawn from the primary container before administration of the fluid from the secondary container is complete.

WARNINGS Whether given orally or by continuous or intermittent intravenous infusion, milrinone 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 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 given by long-term continuous or intermittent infusion does not carry a similar risk. The use of milrinone 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 should be observed closely with the use of continuous electrocardiographic monitoring to allow the prompt detection and management of ventricular arrhythmias.

CONTRAINDICATIONS Milrinone is contraindicated in patients who are hypersensitive to it. Solutions containing dextrose may be contraindicated in patients with known allergy to corn or corn products.

Drug Interactions No untoward clinical manifestations have been observed in limited experience with patients in whom milrinone was used concurrently with the following drugs: digitalis glycosides; lidocaine, quinidine; hydralazine, prazosin; isosorbide dinitrate, nitroglycerin; chlorthalidone, furosemide, hydrochlorothiazide, spironolactone; captopril; heparin, warfarin, diazepam, insulin; and potassium supplements.

ADVERSE REACTIONS Cardiovascular Effects In patients receiving milrinone 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 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 was not shown to be arrhythmogenic in an electrophysiology study. Supraventricular arrhythmias were reported in 3.8% of the patients receiving milrinone. 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. Other Effects Other adverse reactions reported, but not definitely related to the administration of milrinone include hypokalemia, 0.6%; tremor, 0.4%; and thrombocytopenia, 0.4%. 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.

CLINICAL PHARMACOLOGY Milrinone 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, 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 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 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 produces increases in the slope of the left ventricular pressure-dimension relationship, indicating a direct inotropic effect of the drug. Milrinone 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 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. PHARMACOKINETICS Following intravenous injections of 12.5 mcg/kg to 125 mcg/kg to congestive heart failure patients, milrinone had a volume of distribution of 0.38 liters/kg, a mean terminal elimination half-life of 2.3 hours, and a clearance of 0.13 liters/kg/hr. Following intravenous infusions of 0.20 mcg/kg/min to 0.70 mcg/kg/min to congestive heart failure patients, the drug had a volume of distribution of about 0.45 liters/kg, a mean terminal elimination half-life of 2.4 hours, and a clearance of 0.14 liters/kg/hr. These pharmacokinetic parameters were not dose-dependent, and the area under the plasma concentration versus time curve following injections was significantly dose-dependent. Milrinone has been shown (by equilibrium dialysis) to be approximately 70% bound to human plasma protein. The primary route of excretion of milrinone in man is via the urine. The major urinary excretions of orally administered milrinone in man are milrinone (83%) and its O-glucuronide metabolite (12%). Elimination in normal subjects via the urine is rapid, with approximately 60% recovered within the first two hours following dosing and approximately 90% recovered within the first eight hours following dosing. The mean renal clearance of milrinone is approximately 0.3 liters/min, indicative of active secretion. PHARMACODYNAMICS In patients with heart failure due to depressed myocardial function, milrinone produced a prompt dose and plasma concentration related increase in cardiac output and decreases in pulmonary capillary wedge pressure and vascular resistance, which were accompanied by mild-to-moderate increases in heart rate. Additionally, there is no increased effect on myocardial oxygen consumption. In uncontrolled studies, hemodynamic improvement during intravenous therapy with milrinone was accompanied by clinical symptomatic improvement, but the ability of milrinone to relieve symptoms has not been evaluated in controlled clinical trials. The great majority of patients experience improvements in hemodynamic function within 5 to 15 minutes of initiation of therapy. In studies in congestive heart failure patients, milrinone when administered as a loading injection followed by a maintenance infusion produced significant mean initial increases in cardiac index of 25 percent, 38 percent, and 42 percent at dose regimens of 37.5 mcg/kg/0.375 mcg/kg/min, 50 mcg/kg/0.50 mcg/kg/min, and 75 mcg/kg/0.75 mcg/kg/min, respectively. Over the same range of loading injections and maintenance infusions, pulmonary capillary wedge pressure significantly decreased by 20 percent, 23 percent, and 36 percent, respectively, while systemic vascular resistance significantly decreased by 17 percent, 21 percent, and 37 percent. Mean arterial pressure fell by up to 5 percent at the two lower dose regimens, but by 17 percent at the highest dose. Patients evaluated for 48 hours maintained improvements in hemodynamic function, with no evidence of diminished response (tachyphylaxis). A smaller number of patients have received infusions of milrinone for periods up to 72 hours without evidence of tachyphylaxis. The duration of therapy should depend upon patient responsiveness. Milrinone has a favorable inotropic effect in fully digitalized patients without causing signs of glycoside toxicity. Theoretically, in cases of atrial flutter/fibrillation, it is possible that milrinone may increase ventricular response rate because of its slight enhancement of AV node conduction. In these cases, digitalis should be considered prior to the institution of therapy with milrinone. Improvement in left ventricular function in patients with ischemic heart disease has been observed. The improvement has occurred without inducing symptoms or electrocardiographic signs of myocardial ischemia. The steady-state plasma milrinone concentrations after approximately 6 to 12 hours of unchanging maintenance infusion of 0.50 mcg/kg/min are approximately 200 ng/mL. Near maximum favorable effects of milrinone on cardiac output and pulmonary capillary wedge pressure are seen at plasma milrinone concentrations in the 150 ng/mL to 250 ng/mL range.