Prostaglandin E1 (PGE1), known pharmaceutically as alprostadil, is a prostaglandin. It is a drug used in the treatment of erectile dysfunction and has vasodilatory properties. In healthy humans, prostaglandin E1 is biosynthesized "on demand" at its intended site of action from dihomo-γ-linolenic acid. Misoprostol is a synthetic prostaglandin E1 (PGE1) analog that is used to prevent gastric ulcers, to treat missed miscarriage, to induce labor, and to induce abortion.
Alprostadil is also used in maintaining a patent ductus arteriosus in newborns. This is primarily useful when there is threat of premature closure of the ductus arteriosus in an infant with ductal-dependent congenital heart disease, including cyanotic lesions (e.g., pulmonary atresia/stenosis, tricuspid atresia/stenosis, transposition of the great arteries) and acyanotic lesions (e.g., coarctation of the aorta, hypoplastic left heart syndrome, critical aortic stenosis, interrupted aortic arch).
Alprostadil is sold in the United States as urethralsuppositories and in injectable form. The suppositories are sold under the brand name MUSE. The injectable forms are Edex and Caverject. Muse delivers alprostadil as a penile suppository, inserted into the urethra, at least ten minutes before the erection will be needed. Caverject and Edex are similarly fast-acting, but instead are injected by syringe directly into the corpus cavernosum of the penis.
Alprostadil is also available as a generic. The major cost is that it must be mixed by a compounding pharmacy and supplies of alprostadil may be difficult to obtain. There are different formulations, including Bimix and Trimix, which may include papaverine and/or phentolamine. A typical mix might be 30 mg of papaverine, 2 mg of phentolamine, and 20 mcg alprostadil. As a generic, it is much less expensive than the pre-packaged injectables. It is premixed and must be kept refrigerated and the user must load a syringe with the quantity needed.
Alprostadil is also used for critical limb ischemia. It increases blood flow by peripheral vasodilation within 5 minutes and induces angiogenesis. It is most effective when the ankle pressure is at least 30 mmHg and at least one tibial artery is patent.
^Harding LM, Adeniyi A, Everson R, Barker S, Ralph DJ, Baranowski AP (December 2002). "Comparison of a needle-free high-pressure injection system with needle-tipped injection of intracavernosal alprostadil for erectile dysfunction". International Journal of Impotence Research14 (6): 498–501. doi:10.1038/sj.ijir.3900916. PMID12494285.