Metamizole, (a.k.a dipyrone) is a very widely used painkiller, spasm reliever, and fever reliever that also has anti-inflammatory effects.

It was discovered in 1922, and originally marketed in Germany - although it has now been withdrawn there due to adverse side effects. Nevertheless, it's still available - without prescription - in many counties. Brand names include : Novalgina, V-Dalgin, Algimabo, Metilon, Dolocalma and more than 500 others.

Its precise mechanism of action is unknown, although it is believed that inhibiting brain and spinal cord prostaglandin (fat-like molecules that are involved in inflammation, pain and fever) synthesis might be involved.

Source : Wikenigma