Antipyrine metabolites in two populations.

After ingestion of 1 g antipyrine by healthy subjects of either Caucasian (n = 32) or Oriental (n = 18) background, urine was collected for 48 hr. and three major metabolites of antipyrine were determined. 21.8 +/- 1.1 (S.E.)% of the dose was excreted as 4-hydroxyantipyrine (4OHA), 12.7 +/- 0.6% as norantipyrine (NORA) and 5.9 +/- 0.3% as 3-hydroxy-methylantipyrine (3HMA). Oriental and Caucasian subjects showed similar mean recovery of each metabolite. The range of variation (F-test) of metabolite excretions between the 2 groups was again similar except for 3HMA which showed greater variation (p less than 0.01) in Orientals than in Caucasians. The fundamental similarity in antipyrine metabolism in the two populations is remarkable, because metabolite patterns of antipyrine differed significantly between subjects, and because the same two populations are known to differ much in their capacity for other drug oxidations.