Dipyrone is a non-opioid analgesic with antipyretic activity, which was developed by the German company Hoechst AG in 1920 with mass production starting in 1922. It is a pro-drug, which is rapidly metabolized after oral administration to active pyrazolone compounds. Dipyrone is also know under different generic names such as metamizole, noramidopyrine, and others.
Metamizole, or dipyrone, is a painkiller, spasm reliever, and fever reliever that also has anti-inflammatory effects. It is most commonly given by mouth or by injection. It is primarily used for perioperative pain, acute injury, colic, cancer pain, other acute/chronic forms of pain and high fever unresponsive to other agents.
Although it is available over-the-counter in some countries, it is prescription or banned in other countries, due to its potential for adverse events, including agranulocytosis.
Dipyrone was sold as an over-the-counter (OTC) analgesic until the 1970s, at which time it was banned in several countries, including the United States, several European nations, Japan, and Australia following reports of users developing agranulocytosis, occasionally resulting in death. The safety of the drug is still controversial, resulting in varying levels of restriction and regulation worldwide. Dipyrone is still available, however, by prescription and OTC in many countries in Europe, South America, and Asia.