Milrinone is a phosphodiesterase 3 (PDE3) inhibitor used primarily in the treatment of acute heart failure. It works by increasing the levels of cyclic AMP (cAMP) in cardiac and vascular smooth muscle cells, leading to improved cardiac contractility (positive inotropic effect), vasodilation, and enhanced cardiac output. It’s typically administered intravenously in hospital settings, often for short-term management of decompensated heart failure.

Common side effects include arrhythmias, hypotension, and headache. It’s contraindicated in patients with severe obstructive aortic or pulmonic valvular disease.