Phosphodiesterase (particularly PDE10A) (PDE (or PDE10A for specificity))

Papaverine is an opium alkaloid used clinically as a direct smooth muscle relaxant. Its primary molecular target is phosphodiesterase enzymes (notably PDE10A), whose inhibition increases intracellular levels of cAMP and cGMP, disrupting pathways required for sustained muscle contraction. Papaverine also blocks calcium ion channels, further decreasing calcium-dependent contractility. These mechanisms allow papaverine to treat vascular, visceral, and urological spasms. Although it is not structurally related to other opium alkaloids, its unique effects on smooth muscle contraction underpin its clinical utility. Some studies suggest papaverine can affect mitochondrial respiration, offering a secondary route for muscle relaxation in certain tissues.

Other names

PhosphodiesterasecAMP phosphodiesterasecGMP phosphodiesterasePDE10A

Inhibition of phosphodiesterase (especially PDE10A), resulting in increased intracellular cAMP and cGMP levels, causing smooth muscle relaxation. Blockade of calcium ion channels, reducing calcium influx and release, thereby further decreasing contraction. Inhibition of mitochondrial respiration (secondary mechanism in some tissues).