INAMRINONE LACTATE

(in-am'ri-none)

Amrinone
Classifications: cardiac inotropic agent; vasodilator;
Therapeutic: cardiac inotropic agent
Pregnancy Category: C

Availability

5 mg/mL injection

Action

A cardiac inotropic agent with vasodilator activity. Mode of action appears to differ from that of the digitalis glycosides and beta-adrenergic stimulants. In patients with depressed myocardial function, it enhances myocardial contractility, increases cardiac output and stroke volume, and reduces right and left ventricular filling pressure, pulmonary capillary wedge pressure (PCWP), and systemic vascular resistance.

Therapeutic Effect

It reduces preload and afterload by its direct relaxant effect on vascular smooth muscle. Inamrinone produces hemodynamic improvements as well as symptomatic relief in patients in CHF due to ischemic heart disease.

Uses

Short-term management of CHF in patients not adequately controlled by traditional therapy, such as digitalis, diuretics, and vasodilators, and may be used in conjunction with these agents.

Contraindications

Hypersensitivity to inamrinone or to bisulfites; severe aortic or pulmonic valvular disease in lieu of appropriate surgery, acute MI; uncorrected hypokalemia or dehydration; pregnancy (category C). Safe use in children is not established.

Cautious Use

Compromised renal or hepatic function, arrhythmias, hypertrophic subaortic stenosis; decreased platelets; lactation. Concomitant cardiac glycoside therapy recommended in patients with atrial flutter or fibrillation.

Route & Dosage

Congestive Heart Failure
Adult: IV 0.75 mg/kg bolus given slowly over 2–3 min, then start infusion at 5–10 mcg/kg/min, may repeat bolus in 30 min (max: 10 mg/kg/d)

Renal Impairment
Cl_cr <10 mL/min: give 50–75% of dose

Administration

Intravenous

PREPARE: Direct: Give loading dose undiluted or diluted by adding 1 mL of NS or 0.45% NS to each 5 mg (1 mL). IV Infusion: ??Dilute 300 mg (60 mL) in 60 mL of NS or 0.45% NS to yield 2.5 mg/mL.??Natural color is clear yellow. Discard discolored solutions and those with precipitate.

ADMINISTER: Direct: Give loading dose over 2–3 min. May inject into a running D5W infusion through Y-connector or directly. IV Infusion: ??Give diluted solution at a rate of 5–10 mg/kg/min.??Use infusion pump to regulate rate.

INCOMPATIBILITIES Solution/additive: Sodium bicarbonate, dextrose-containing solutions. Y-site: Furosemide, sodium bicarbonate.

Use all diluted solutions within 24 h.
Protect ampules from light.

Adverse Effects (≥1%)

Body as a Whole: Hypersensitivity (pericarditis, pleuritis; myositis with interstitial shadows on chest x-ray and elevated sedimentation rate; vasculitis with nodular pulmonary densities, hypoxemia, ascites, jaundice). CV: Hypotension, arrhythmias. Endocrine: Nephrogenic diabetes insipidus. GI: Nausea, vomiting, anorexia, abdominal cramps, hepatotoxicity. Hematologic: Asymptomatic thrombocytopenia.

Interactions

Drug: Possibility of excessive hypotension with disopyramide.

Pharmacokinetics

Onset: 2–5 min. Peak: 10 min. Duration: About 2 h. Distribution: Unknown if it crosses placenta or into breast milk. Metabolism: In liver. Elimination: Primarily in urine. Half-Life: 3.6–7.5 h.

Nursing Implications

Assessment & Drug Effects

Monitor for therapeutic effectiveness: Increased cardiac output, decreased PCWP, relief of symptoms of CHF. Central venous pressure may be used to assess hypotension and blood volume.
Monitor BP, heart rate, and respirations and keep physician informed. Rate of administration and duration of therapy are prescribed according to clinical response and adverse effects.
Consult physician for guidelines. In general, rate of infusion should be slowed or stopped with excessive drop in BP or arrhythmias.
Monitor infusion site to prevent extravasation.
Monitor I&O ratio and pattern and daily weights. Improvement in cardiac output enhances diuresis with consequent danger of hypokalemia and arrhythmias, particularly in digitalized patients.
Lab tests: Monitor closely platelet counts, liver enzymes, fluid and electrolyte balances, renal function.
Correct hypokalemia before and during therapy.
Note: If platelet count falls below 150,000/mm³, report immediately to physician; may indicate thrombocytopenia.
Allergy alert: IV preparation contains sodium metabisulfite, a reducing agent to which certain susceptible individuals are allergic. Discontinue immediately if patient shows hypersensitivity reactions.
Observe patient closely when drug is withdrawn after prolonged therapy; clinical deterioration may occur within hours.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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