Autacoids or "autocoids" are biological factors which act like local hormones, have a brief duration, and act near the site of synthesis. The word autacoids comes from the Greek "Autos" (self) and "Acos" (relief, i.e. drug). The effect of autacoids are mostly localized but large amounts can be produced and moved into circulation. Autacoids may thus have systemic effect by being transported via circulation. These regulating molecules are also metabolized locally. So the compounds are produced locally, they act locally and are metabolised locally. Autacoids can have many different biological actions including modulation of the activity of smooth muscles, glands, nerves, platelets and other tissues.