ChEBI: Papaverine is a benzylisoquinoline alkaloid that is isoquinoline substituted by methoxy groups at positions 6 and 7 and a 3,4-dimethoxybenzyl group at position 1. It has been isolated from Papaver somniferum. It has a role as a vasodilator agent and an antispasmodic drug. It is a benzylisoquinoline alkaloid, a member of isoquinolines and a dimethoxybenzene.NCI Thesaurus (NCIt): Papaverine is an opiate alkaloid isolated from the plant Papaver somniferum and produced synthetically. As a direct-acting smooth muscle relaxant, papaverine is not closely related to the other opium alkaloids in structure or pharmacological actions; its mechanism of action may involve the non-selective inhibition of phosphodiesterases and direct inhibition of calcium channels. This agent also exhibits antiviral activity against respiratory syncytial virus, cytomegalovirus, and HIV. (NCI04)