4,4'-Dihydroxyphenazone as an urinary metabolite of phenazone in different species including man

4,4'-Dihydroxyphenazone (4-hydroxy-1-4'-hydroxyphenyl)-2,3-dimethyl-3-pyrazoline-5-one) was isolated as a metabolite of phenazone (antipyrine) after acid hydrolysis of rat urine. This was characterized and identified by NMR, MS, IR, UV, Fp and epsilon270. After dosage with phenazone, 4,4'-dihydroxyphenazone is excreted in conjugated form by man, rabbit, guinea pig and rat. In the rat it is further shown, that conjugates of 4,4'-dihydroxyphenazone are formed by glucuronidation as well as by sulfatation. The metabolite seems to add substantially to the overall metabolic pattern of phenazone in these species.