Aminophenazone

Aminophenazone, also known as pyramidon, is a pyrazolone derivative that was used as a medication. It was introduced in the late 19th century and was prescribed for its analgesic and antipyretic properties. It was commonly used to relieve pain and reduce fever. Aminophenazone is structurally related to antipyrine and has a similar mechanism of action. It works by inhibiting cyclooxygenase enzymes, which are involved in the production of prostaglandins, substances that contribute to pain and fever.

However, the use of aminophenazone declined significantly due to concerns about its safety profile. A major adverse effect associated with its use was agranulocytosis, a potentially fatal condition characterized by a severe drop in white blood cell count, making individuals highly susceptible to infection. This serious side effect led to its withdrawal from many markets and restricted use in others. Due to these safety concerns, it is no longer widely prescribed and has largely been replaced by other analgesics and antipyretics with better safety profiles.