What are phosphodiesterase inhibitors?

Cyclic-AMP is broken down by an enzyme called cAMP-dependent phosphodiesterase (PDE) The isoform of this enzyme that is targeted by currently used clinical drugs is the type 3 form (PDE3). Inhibition of this enzyme prevents cAMP breakdown and thereby increases its intracellular concentration. ➔This increases cardiac inotropy, chronotropy and dromotropy The cardiac and vascular effects of cAMP-dependent PDE inhibitors cause : ✓Cardiac stimulation= Increases cardiac output ✓Systemic vascular resistance decreases= Lower arterial pressure. ✓Moderate dilation of both artery and veins leading to decrease in afterload and preload Because of the dual cardiac and vascular effects of these compounds, they are sometimesreferred to as "inodilators."