metamizol

Metamizol, also known as dipyrone, is an analgesic and antipyretic medication belonging to the class of painkillers that contain a sulfonamide group. It was first synthesized in the early 20th century and introduced for clinical use in the 1930s. Unlike non‑steroidal anti‑inflammatory drugs, metamizol is not classified as a non‑steroidal anti‑inflammatory agent; it is considered a non‑opioid analgesic, although its precise mechanism of action remains partially understood. It is believed to inhibit prostaglandin synthesis by acting on cyclooxygenase enzymes and may also alter pain signal transmission at the spinal level.

The compound is employed for the relief of moderate to severe pain and fever, especially in patients who cannot tolerate or have contraindications to other analgesics. It is frequently used pre‑operatively and post‑operatively for anesthesia‑related pain, and for breakthrough cancer pain. In some countries, metamizol is a prescription‑only medication, while in others it is available over the counter.

Metamizol is generally well tolerated, but it carries a risk of serious hypersensitivity reactions, including agranulocytosis, a potentially life‑threatening drop in white blood cell count. Consequently, many jurisdictions have restricted or banned its use due to safety concerns. Other adverse effects may include rash, hypotension, and transient gastrointestinal discomfort. Contraindications include a known hypersensitivity to sulfonamides, impaired renal function, and certain hematological disorders. Precautions are advised in pregnancy and lactation, with limited data on safety in these populations.

Regulatory status varies widely; some European nations have phased out metamizol from the market, whereas it remains commonly used in Russia, Brazil, India, and parts of Latin America. The ongoing debate over its risk–benefit profile continues to influence pharmaceutical policy and clinical practice guidelines.