About Alprostadil Prostaglandin E1, Vasodilator. Mechanism of Action of Alprostadil Patent ductus arteriosus: Alprostadil is a prostaglandin E1 analogue which maintains patency of the ductus arteriosus of fetus. After birth, prostaglandin production falls and the ductus closes. When there is congenital heart defect, it is necessary that the ductus remain patent until corrective surgery can be accomplished. In such conditions Alprostadil maintains patency pending surgery. Erectile dysfunction: Alprostadil produces vasodilatation. It increases blood flow to the penis by expanding blood vessels (cavernosal arteries). This allows blood flow to the lacunar spaces of the penis and produce erection. Alprostadil is used to produce erections in some men who need treatment for erectile dysfunction (sexual impotence). This medicine causes an erection because it increases the blood flow to the penis. Alprostadil injection should not be used as a sexual aid by men who do not have erectile