Aminopyrine

Aminopyrine, also known as aminophenazone or pyramidon, is a synthetic analgesic and antipyretic drug. It belongs to the pyrazolone class of compounds. Historically, it was widely used to reduce fever and alleviate pain. Aminopyrine was synthesized in the late 19th century and quickly gained popularity for its effectiveness.

However, concerns about its safety profile emerged over time. The most significant adverse effect associated with aminopyrine is agranulocytosis, a severe and potentially fatal condition characterized by a drastic reduction in white blood cells. This risk led to its withdrawal from the market in many countries. Despite these safety concerns, aminopyrine is still used in some regions, particularly in veterinary medicine.

The mechanism of action of aminopyrine is not fully understood but is believed to involve inhibition of cyclooxygenase (COX) enzymes, similar to other nonsteroidal anti-inflammatory drugs (NSAIDs). This inhibition reduces the production of prostaglandins, which are involved in pain and fever signaling. Research into its metabolism has revealed that it can be converted to other active compounds, including 4-methylaminoantipyrine. The drug is primarily metabolized in the liver.