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Inamrinone (Inamrinone) - Indications and Dosage

 
 



INDICATIONS AND USAGE

Inamrinone injection is for the short-term management of congestive heart failure. Because of limited experience and potential for serious adverse effects (see ADVERSE REACTIONS), inamrinone should be used only in patients who can be closely monitored and who have not responded adequately to digitalis, diuretics, and/or vasodilators. Experience with intravenous inamrinone in controlled trials does not extend beyond 48 hours of repeated boluses and/or continuous infusions.

Whether given orally, continuously intravenously, or intermittently intravenously, neither inamrinone nor any other cyclic-AMP-dependent inotrope has been shown in controlled trials to be safe or effective in the long-term treatment of congestive heart failure. In controlled trials of chronic oral therapy with various such agents (including inamrinone), symptoms were not consistently alleviated, and the cyclic-AMP-dependent inotropes were consistently associated with increased risks of hospitalization and death. Patients with NYHA Class IV symptoms appeared to be at particular risk.

DOSAGE AND ADMINISTRATION

Loading doses of inamrinone injection should be administered as supplied (undiluted). Infusions of inamrinone may be administered in normal or half normal saline solution to a concentration of 1 mg/mL to 3 mg/mL. Diluted solutions should be used within 24 hours.

Inamrinone injection may be administered into running dextrose (glucose) infusions through a Y-Connector or directly into the tubing where preferable.

Chemical Interactions

A chemical interaction occurs slowly over a 24-hour period when the intravenous solution of inamrinone is mixed directly with dextrose (glucose)-containing solutions. THEREFORE, INAMRINONE SHOULD NOT BE DILUTED WITH SOLUTIONS THAT CONTAIN DEXTROSE (GLUCOSE) PRIOR TO INJECTION.

A chemical interaction occurs immediately, which is evidenced by the formation of a precipitate when furosemide is injected into an intravenous line of an infusion of inamrinone. Therefore, furosemide should not be administered in intravenous lines containing inamrinone.

The following procedure is recommended for the administration of inamrinone injection:

1. Initiate therapy with a 0.75 mg/kg loading dose given slowly over 2 to 3 minutes.

LOADING DOSE DETERMINATION

0.75 mg/kg (undiluted)

Patient Weight in kg30405060708090100110120
mL of undiluted Inamrinone Injection4.567.5910.51213.51516.518

2. Continue therapy with a maintenance infusion between 5 mcg/kg/min and 10 mcg/kg/min.

3. Based on clinical response, an additional loading dose of 0.75 mg/kg may be given 30 minutes after the initiation of therapy.

4. The rate of infusion usually ranges from 5 mcg/kg/min to 10 mcg/kg/min such that the recommended total daily dose (including loading doses) does not exceed 10 mg/kg. A limited number of patients studied at higher doses support a dosage regimen up to 18 mg/kg/day for shortened durations of therapy.

The following infusion rate chart may be used to assure that the calculations are made correctly.

To utilize the chart, the concentration of inamrinone infusion solution used must be 2.5 mg/mL (2500 mcg/mL). This concentration is prepared by mixing the inamrinone solution with an equal volume of diluent (normal or half normal saline).

INAMRINONE IV INFUSION RATE (mL/hr) CHART

Using 2.5 mg/mL Infusion Concentration 1

Patient Weight in kg30405060708090100110120

Dosage:

5.0 mcg/kg/min

456781011121314
7.5 mcg/kg/min57911131416182022
10.0 mcg/kg/min7101214171922242629

1 Dilution: To prepare the 2.5 mg/mL concentration recommended for infusion mix inamrinone with an equal volume of diluent. For example, mix three 20 mL vials of inamrinone (3 x 20 mL = 60 mL) with 60 mL of diluent for a total volume of 120 mL of the final 2.5 mg/mL solution of inamrinone.

Example: A 70 kg patient would require a loading dose of 10.5 mL of undiluted inamrinone. If the physician selects a dose of 7.5 mcg/kg/min for the infusion, the flow rate would be 13 mL/hr at the 2.5 mg/mL concentration of inamrinone.

5. The rate of administration and the duration of therapy should be adjusted according to the response of the patient. The physician may wish to reduce or titrate the infusion downward based on clinical responsiveness or untoward effects.

The above dosing regimens can be expected to place most patients’ plasma concentration of inamrinone at approximately 3 mcg/mL. Increases in cardiac index show a linear relationship to plasma concentration of a range of 0.5 mcg/mL to 7 mcg/mL. No observations have been made at greater plasma concentrations.

Patient improvement may be reflected by increases in cardiac output, reduction in pulmonary capillary wedge pressure, and such clinical responses as a lessening of dyspnea and an improvement in other symptoms of heart failure, such as orthopnea and fatigue.

Monitoring central venous pressure (CVP) may be valuable in the assessment of hypotension and fluid balance management. Prior correction or adjustment of fluid/electrolytes is essential to obtain satisfactory response with inamrinone.

Parenteral drug products should be inspected visually and should not be used if particulate matter or discoloration is observed.

HOW SUPPLIED

Inamrinone Injection USP is supplied in single-dose vials of 20 mL sterile, clear yellow solution individually boxed. NDC 55390-042-10.

Each 1 mL contains inamrinone lactate equivalent to 5 mg of inamrinone.

Protect from light. Packaging is light resistant for protection during storage. Retain in carton until time of use.

Store at controlled room temperature 15° to 30°C (59° to 86°F).

Manufactured by:                                                                                  Manufactured for:

Ben Venue Laboratories, Inc.                                                                 Bedford Laboratories™

Bedford, OH 44146                                                                               Bedford, OH 44146

August 2002                                                                                          AMR-P01

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