Papaverine Hydrochloride is an opium alkaloid that can directly cause smooth muscle expansion and differs from other opium alkaloids in this respect. It is used to treat a variety of smooth muscle spasms, including vascular spasms caused by acute myocardial infarction and angina pectoris, and visceral spasms. The mechanism of action of Papaverine is non-selective inhibition of phosphodiesterase and direct inhibition of calcium channels. It also has antiviral activity against the respiratory syncytial virus (RSV), HIV, and cytomegalovirus.
