Dipyrone

Dipyrone, also known as metamizol or metamizole, is a non-opioid analgesic and antipyretic that belongs to the pyrazolone class. It is used for the relief of moderate to severe acute pain and for fever, and in some settings has antiemetic and spasmolytic effects. Its anti-inflammatory action is generally considered weaker than that of classic nonsteroidal anti-inflammatory drugs.

The exact mechanism of action is not fully understood. Dipyrone is thought to reduce prostaglandin synthesis and may act through central pathways, contributing to its analgesic and antipyretic effects. It is rapidly absorbed when taken orally and is extensively metabolized in the liver to active metabolites, such as 4-hydroxyantispiro compounds, which contribute to its effects. It is usually eliminated via the kidneys.

Safety and regulatory considerations are a central aspect of dipyrone use. A rare but serious adverse effect is agranulocytosis (bone marrow suppression), which can be fatal. Other hematologic, hepatic, and hypersensitivity reactions have been reported. Because of these risks, dipyrone is restricted or banned in several countries and is then available only under medical supervision or not at all. Contraindications generally include known hypersensitivity to the drug and certain hematologic disorders; many guidelines advise caution or avoidance during pregnancy and lactation, and its use may be limited in children or in patients with prior bone marrow issues.

In practice, dipyrone is used in some regions where its benefits are considered to outweigh the risks, with monitoring and restrictions in place. The drug’s status varies by country and over time.