4-Methylaminoantipyrine (hydrochloride)

4-Methylaminoantipyrine is a major active metabolite of the non-opioid prodrug metamizole (Item No. 15771).{25749} It is formed from metamizole by non-enzymatic hydrolysis in the gastrointestinal tract.{57230} 4-Methylaminoantipyrine (0.1 mM) inhibits production of prostaglandin E2 (PGE2; Item No. 14010) induced by the calcium ionophore A23187 (Item Nos. 11016 | 22030) in isolated mouse peritoneal macrophages.{57231} It increases the paw withdrawal threshold in a rat model of carrageenan-induced hyperalgesia when administered at a dose of 160 µg/paw.{57232} 4-Methylaminoantipyrine (60, 90, and 120 mg/kg) reduces LPS-induced pyrexia in rats.{57233} It is also a potential impurity found in commercial preparations of metamizole.{57234}