Episode Details

Core Profile & Mechanism Milrinone is a parenteral positive inotrope and vasodilator with selective phosphodiesterase III (PDE3) inhibitor activity. By preventing cyclic adenosine monophosphate (cAMP) breakdown in cardiac and vascular muscle cells, it increases myocardial contractility, causes vasodilation, and improves diastolic relaxation (lusitropy). This dual action reduces preload, afterload, and systemic vascular resistance with little to no chronotropic activity. Therapeutic effects occur at plasma levels of 100 to 300 ng/mL.

Primary Indications Milrinone is used for the short-term treatment of acute heart failure and other low cardiac output states like cardiogenic shock or post-cardiac surgery low cardiac output syndrome (LCOS). It can provide long-term palliative support in stage D heart failure patients awaiting transplant or mechanical circulatory support. Off-label uses include pediatric septic shock or postresuscitation stabilization, cerebral vasospasm after aneurysmal subarachnoid hemorrhage, and persistent pulmonary hypertension of the newborn (PPHN) with poor nitric oxide response.

Dosing & Administration

• Adult HF Dosing: A 50 mcg/kg IV loading dose over 10–60 minutes (though heart failure guidelines do not recommend a bolus), followed by 0.125 to 0.75 mcg/kg/minute continuous infusion.
• Renal Adjustments: Elimination is primarily renal (83% excreted unchanged in urine, half-life of 2.4 hours). For CrCl ≤ 50 mL/min, the adult continuous infusion rate must be adjusted down sequentially from 0.43 mcg/kg/min (CrCl 41–50) down to 0.2 mcg/kg/min (CrCl ≤ 5). Pediatric rates also require reductions for CrCl < 50 mL/min.
• Administration Safety: Standard infusion is 200 mcg/mL, diluted in 0.45% or 0.9% NaCl or 5% Dextrose, run via a controlled device. It is not FDA-approved for intraosseous use, but the same doses can be given IO if IV access is unavailable.

Critical Safety & Adverse Reactions

• Incompatibilities: Milrinone must never be co-administered with furosemide, as precipitation occurs immediately in the same line. It also cannot be given simultaneously with blood.
• Arrhythmias & Monitoring: Continuous ECG monitoring is mandatory. Milrinone carries a substantial risk of serious ventricular arrhythmias (VT up to 12%, VF 0.2%), atrial flutter/fibrillation (up to 8%), supraventricular tachycardia, and premature ventricular contractions.
• Hypotension & Other Risks: Hypotension occurs in 2.9% to 10.7% of patients. To reduce this risk, clinicians often avoid the loading dose in septic shock and neonatal PPHN. Thrombocytopenia is a delayed reaction occurring in up to 58% of patients.