Inamrinone

Pronunciation: in-AM-rih-nohn
Class: Inotropic agent

Trade Names:
Inamrinone
- Injection 5 mg/mL (as lactate)

Pharmacology

Positive inotropic agent with vasodilator activity.

Pharmacokinetics

Distribution

Vd is 1.2 L/kg. 10 to 49% is protein bound. The t _½ is 4.6 min.

Metabolism

Several metabolites: N-glycolyl, N-acetate, O-glucaronide.

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Elimination

The t _½ is 3.6 h. The primary route is via the urine.

Peak

10 minutes.

Duration

30 min to 2 h (dose-dependent)

Special Populations

There is increased Vd and decreased elimination t _½ .

In CHF patients the mean elimination is t _½ of 5.8 h. Monitor hemodynamic response or drug level.

Indications and Usage

Short-term management of CHF in patients whose condition can be closely monitored and who have not responded adequately to digitalis, diuretics, or vasodilators.

Contraindications

Hypersensitivity to bisulfites.

Dosage and Administration

IV Initial dose: 0.75 mg/kg bolus slowly over 2 to 3 min. Maintenance: 5 to 10 mcg/kg/min; additional 0.75 mg/kg bolus may be given 30 min after initiating therapy, not to exceed total daily dose of 10 mg/kg.

General Advice

• Administer as supplied or dilute in 0.5% or 0.9% saline to a concentration of 1 to 3 mg/mL.
• Do not dilute in dextrose-containing solutions, although product may be injected into running dextrose infusion through Y-connector or directly into tubing. Do not infuse product and furosemide through same line.
• Use diluted solutions within 24 h.

Storage/Stability

Protect ampules from light. Store at room temperature.

Drug Interactions

None well documented.

Incompatibility

Chemical interaction occurs slowly over 24 h when mixed directly with dextrose-containing solutions. Do not inject furosemide into IV line containing inamrinone; immediate precipitate forms.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Arrhythmia; hypotension.

GI

Nausea; vomiting.

Hematologic

Thrombocytopenia.

Precautions

Pregnancy

Category C .

Lactation

Undetermined.

Children

Safety and efficacy not established.

Sulfite Sensitivity

May cause allergic-type reaction in susceptible patients.

Arrhythmias

Supraventricular and ventricular arrhythmias have occurred.

Fluid balance

Vigorous diuretic therapy may cause inadequate response to inamrinone therapy; liberalization of fluids may be needed. CVP monitoring has been advocated.

Hepatotoxicity

Dose may be reduced or drug may be discontinued if there are alterations in liver enzymes; if alterations occur with clinical symptoms, drug is discontinued.

Post MI

Not recommended during acute phase.

Severe aortic or pulmonic valvular disease

Not recommended.

Thrombocytopenia

More common in patients on prolonged therapy.

Overdosage

Symptoms

Arrhythmias, excessive hypotension.

Patient Information

• Instruct patient to avoid sudden position changes to prevent orthostatic hypotension.
• Advise patient to notify health care provider of shortness of breath and increased chest pain.

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