Alprostadil is a non–PDE-5 inhibitor option for treating erectile dysfunction (ED). It is a synthetic version of prostaglandin E1, which works by relaxing smooth muscle and dilating blood vessels in the penis to increase blood flow. Unlike oral medications, alprostadil is given either as a penile injection (Caverject, Edex) or as a urethral suppository (MUSE). Its onset is rapid—usually within 5–20 minutes—and it doesn’t require sexual stimulation to be effective. Common side effects include penile pain, prolonged erection (priapism), and local irritation; with injections, there is also a small risk of bleeding or scar tissue formation at the injection site.