Inamrinone

Inamrinone, also known as amrinone, is a phosphodiesterase-3 (PDE3) inhibitor used as an inodilator in the management of acute heart failure and cardiogenic shock. By inhibiting PDE3, it increases cyclic adenosine monophosphate (cAMP) within cardiac myocytes and vascular smooth muscle, producing positive inotropy and vasodilation.

In the heart, elevated cAMP enhances myocardial contractility and can improve stroke volume, while in vascular smooth muscle it promotes vasodilation, reducing both preload and afterload. These combined effects can improve cardiac output and tissue perfusion in the short term.

Administration and pharmacokinetics are oriented toward short-term, intravenous use in hospital settings. Amrinone has a rapid onset of action and a relatively short half-life, necessitating continuous infusion for ongoing hemodynamic support during acute decompensation.

Clinical use is typically limited to acute decompensated heart failure or certain cases of cardiogenic shock when conventional therapies are insufficient or as a bridge to other interventions. It is not indicated for chronic management of heart failure.

Adverse effects commonly include hypotension, tachyarrhythmias, and thrombocytopenia. Other potential issues include hepatic dysfunction and electrolyte disturbances. Because of its vasodilatory effects, careful monitoring of blood pressure and rhythm is required, especially when combined with other vasoactive or antiarrhythmic drugs.

Although amrinone can improve hemodynamics, randomized trials have not consistently shown a survival benefit, contributing to its more restricted use in favor of other PDE3 inhibitors, such as milrinone, in many clinical settings.