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Inamrinone (Inamrinone) - Warnings and Precautions

 
 



WARNINGS

Contains sodium metabisulfite, a sulfite that may cause allergic-type reactions including anaphylactic symptoms and life-threatening or less severe asthmatic episodes in certain susceptible people. The overall prevalence of sulfite sensitivity in the general population is unknown and probably low. Sulfite sensitivity is seen more frequently in asthmatic than in nonasthmatic people.

PRECAUTIONS

General

Inamrinone should not be used in patients with severe aortic or pulmonic valvular disease in lieu of surgical relief of the obstruction. Like other inotropic agents, it may aggravate outflow tract obstruction in hypertrophic subaortic stenosis.

During intravenous therapy with inamrinone, blood pressure and heart rate shouId be monitored and the rate of infusion slowed or stopped in patients showing excessive decreases in blood pressure.

Patients who have received vigorous diuretic therapy may have insufficient cardiac filling pressure to respond adequately to inamrinone, in which case cautious liberalization of fluid and electrolyte intake may be indicated.

Supraventricular and ventricular arrhythmias have been observed in the very high-risk population treated. While inamrinone per se has not been shown to be arrhythmogenic, the potential for arrhythmia, present in congestive heart failure itself, may be increased by any drug or combination of drugs.

Thrombocytopenia and hepatotoxicity have been noted (see ADVERSE REACTIONS).

USE IN ACUTE MYOCARDIAL INFARCTION

No clinical trials have been carried out in patients in the acute phase of postmyocardial infarction. Therefore, inamrinone is not recommended in these cases.

Laboratory Tests

Fluid and Electrolytes

Fluid and electrolyte changes and renal function should be carefully monitored during inamrinone therapy. Improvement in cardiac output with resultant diuresis may necessitate a reduction in the dose of diuretic. Potassium loss due to excessive diuresis may predispose digitalized patients to arrhythmias. Therefore, hypokalemia should be corrected by potassium supplementation in advance of or during inamrinone use.

Drug Interactions

In a relatively limited experience, no untoward clinical manifestations have been observed in patients in which inamrinone was used concurrently with the following drugs: digitalis glycosides; lidocaine, quinidine; metoprolol, propranolol; hydralazine, prazosin; isosorbide dinitrate, nitroglycerine; chlorthalidone, ethacrynic acid, furosemide, hydrochlorothiazide, spironolactone; captopril; heparin, warfarin; potassium supplements; insulin; diazepam.

One case report of excessive hypotension has been reported when inamrinone was used concurrently with disopyramide.

Until additional experience is available, concurrent administration with disopyramide should be undertaken with caution.

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.

Carcinogenesis, Mutagenesis, Impairment of Fertility

There was no suggestion of a carcinogenic potential with inamrinone when administered orally for up to two years to rats and mice at dose levels up to the maximally tolerated dose of 80 mg/kg/day.

The mouse micronucleus test (at 7.5 to 10 times the maximum human dose) and the Chinese hamster ovary chromosome aberration assay were positive indicating both clastogenic potential and suppression of the number of polychromatic erythrocytes. However, the Ames Salmonella assay, mouse lymphoma study, and cultured human lymphocyte metaphase analysis were all negative. The clastogenic effects are in contrast to negative results obtained in the rat male and female fertility studies, and a three-generation study in rats, both with oral dosing.

Slight prolongation of the rat gestation period was seen in these studies at dose levels of 50 mg/kg/day and 100 mg/kg/day. Dystocia occurred in dams receiving 100 mg/kg/day resulting in increased numbers of stillbirths, decreased litter size, and poor pup survival.

Pregnancy

Teratogenic Effects- Pregnancy Category C

In New Zealand white rabbits, inamrinone has been shown to produce fetal skeletal and gross external malformations at oral doses of 16 mg/kg and 50 mg/kg which were toxic for the rabbit. Studies in French Hy/Cr rabbits using oral doses up to 32 mg/kg/day did not confirm this finding. No malformations were seen in rats receiving inamrinone intravenously at the maximum dose used, 15 mg/kg/day (approximately the recommended daily intravenous dose for patients with congestive heart failure). There are no adequate and well-controlled studies in pregnant women. Inamrinone should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Nursing Mothers

Caution should be exercised when inamrinone is administered to nursing women, since it is not known whether it is excreted in human milk.

Pediatric Use

Safety and effectiveness in pediatric patients have not been established.

Page last updated: 2006-10-11

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