Abstract
1. [14C]Prenazone administered to rats (60 mg/kg) as a suspension by stomach tube was excreted to the extent of 43% dose in the urine in 24 h with only 3% in the faeces. After four days the cumulative excretion amounted to 52% in the urine and 15% in the faeces.
2. The two major urinary metabolites were trans-4-(3'-hydroxymethylbut-2'-enyl)-1,2-diphenylpyrazolidine-3, 5-dione (monohydroxyprenazone) and trans-4-(3'-hydroxymethylbut-2'-enyl)-1 -(p-hydroxyphenyl)-2-phenylpyrazolidine-3,5-dione- (dihydroxyprenazone). These did not appear to be conjugated.
3. Only very small amounts of unchanged prenazone were found in the urine.
4. The above monhydroxyprenazone and related compounds were synthesized.