Cardiovascular Effects: In patients receiving PRIMACOR 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 PRIMACOR 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. PRIMACOR was not shown to be arrhythmogenic in an electrophysiology study. Supraventricular arrhythmias were reported in 3.8% of the patients receiving PRIMACOR. 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 PRIMACOR.

Other Effects

Other adverse reactions reported, but not definitely related to the administration of PRIMACOR 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 PRIMACOR:

Isolated spontaneous reports of bronchospasm and anaphylactic shock.

Liver function test abnormalities and skin reactions such as rash.

Administration site conditions: Infusion site reaction.

Read the Primacor IV (milrinone) Side Effects Center for a complete guide to possible side effects »

No untoward clinical manifestations have been observed in limited experience with patients in whom PRIMACOR 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.

Chemical Interactions

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

Last reviewed on RxList: 7/2/2008
This monograph has been modified to include the generic and brand name in many instances.