Prostaglandin E1 agonists are used to treat erectile dysfunction. They work by relaxing blood vessels and increasing blood flow to the penis to allow an erecion to happen. Prostaglandin E1 agonists come in different forms, including injections and urethral suppositories. Examples include alprostadil injection (Caverject, Edex) and alprostadil urethral suppository (Muse). You can discuss with your healthcare team which option might be right for you.