A naturally occuring prostaglandin E (PGE1) which displays a variety of pharmacologic actions. Alprostadil is a potent vasodilator agent that increases peripheral blood flow, inhibits platelet aggregation, and induces bronchodilation. As an agent used in the treatment of erectile dysfunction, alprostadil produces corporal smooth muscle relaxation by the activation of adenylate cyclase and the subsequent accumulation of 3-5-cAMP. This agent is also used to maintain the patency of the ductus arteriosus in neonates until corrective or palliative surgery can be performed. (NCI04)