prostaglandin

n.

one of a group of hormone-like substances present in a wide variety of tissues and body fluids (including the uterus, brain, lungs, kidney, and semen). Prostaglandins have many actions; for example, they cause contraction of smooth muscle (including that of the uterus), dilation of blood vessels, and are mediators in the process of inflammation (aspirin and other NSAIDs act by blocking their production). They are also involved in the production of mucus in the stomach, which provides protection against acid gastric juice; use of NSAIDs reduces this effect and predisposes to peptic ulceration, the principal side-effect of these drugs. There are nine classes of prostaglandins (PGA–I), within which individual prostaglandins are denoted by numerals (e.g. PGE₁). Synthetic prostaglandins are used to induce labour or produce abortion (see dinoprostone, gemeprost) and to treat peptic ulcers (see misoprostol), congenital heart disease in newborn babies (see alprostadil), and glaucoma (see latanoprost).