ATC Group: N02BB Pyrazolones

Aminophenazone is a pyrazolone with analgesic, anti-inflammatory, and antipyretic properties but has risk of agranulocytosis. A breath test with 13C-labeled aminopyrine has been used as a non-invasive measure of cytochrome P-450 metabolic activity in liver function tests. It is also used in measuring the total body water in the human body system.

Metamizole sodium is a pyrazolone derivative with analgesic, antipyretic and slight antiinflammatory and spasmolytic properties. It has the most potent analgesic effect of all the pyrazolone derivatives. As with other analgesics, its mechanism of action has not been elucidated in detail. It includes inhibition of prostaglandin synthesis (PGE1 and PGE2) and reversible inhibition of platelet aggregation. It inhibits cyclo-oxygenase and influences the effect of arachidonic acid.

Phenazone has analgesic and antipyretic properties. Topically, solutions have been used locally as ear drops in disorders such as otitis media because of its local anti-inflammatory and analgesic action.

Propyphenazone is a pyrazolone derivative with anti-inflammatory, analgesic and antipyretic activity. As it is structurally related to aminophenazone it has been associated with severe blood dyscrasias. However, it cannot be transformed into potentially carcinogenic nitrosamines and has therefore been widely used as a replacement drug for aminophenazone.