A Comprehensive Monograph on Papaverine (DB01113)

1.0 Executive Summary

Papaverine is a non-narcotic, benzylisoquinoline alkaloid derived from the opium poppy, Papaver somniferum. Structurally and pharmacologically, it is distinct from the analgesic phenanthrene alkaloids of opium, such as morphine and codeine, and lacks their central nervous system and analgesic effects.[1] The primary mechanism of action of Papaverine is direct-acting smooth muscle relaxation, achieved through a multi-faceted approach that includes non-selective inhibition of phosphodiesterase (PDE) enzymes and direct modulation of calcium channels.[4] This inhibition of PDEs leads to an accumulation of intracellular cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), which triggers a cascade resulting in vasodilation and spasmolysis.[6]

Clinically, this pharmacological profile underpins its approved indications for the treatment of visceral spasms of the gastrointestinal tract and vasospasms associated with cerebral and peripheral ischemia.[1] Papaverine has also found a prominent, albeit largely off-label, role in modern medicine, most notably for the management of erectile dysfunction via intracavernosal injection, where its potent local vasodilatory effects are leveraged.[1] Its use extends to intraoperative settings to prevent or relieve arterial spasm during microsurgical and cardiovascular procedures.[1]