Azacosterol (INNTooltip International Nonproprietary Name), or azacosterol hydrochloride (USANTooltip United States Adopted Name) (brand name Ornitrol), also known as 20,25-diazacholesterol, is a cholesterol-lowering drug (hypocholesteremic), which was marketed previously, but has since been discontinued.[1][2][3] It is also an avianchemosterilant used to control pestpigeon populations via inducing sterility.[4] The drug is a sterol and derivative of cholesterol in which two carbonatoms have been replaced with nitrogen atoms.[5]