Antipyrine metabolite formation in children in the acute phase of malnutrition and after recovery.

1. The plasma elimination rate of antipyrine and the urinary excretion of antipyrine and its primary metabolites 4-hydroxy-antipyrine, norantipyrine, 3-hydroxymethyl-antipyrine and 3-carboxyantipyrine were measured in five children in the acute phase of malnutrition and after recovery. The results were compared with those obtained in 3 normal children. 2. Upon nutritional rehabilitation antipyrine clearance increased from 0.65 +/- 0.14 ml min-1 kg-1 to 1.07 +/- 0.20 ml min-1 kg-1. 3. The urinary excretion of 4-hydroxy-antipyrine increased from 6.1 +/- 4.5 to 14.7 +/- 5.9%, norantipyrine from 8.8 +/- 5.7 to 14.3 +/- 5.4 and 3-hydroxy-methyl-antipyrine from 11.8 +/- 8.3 to 20.5 +/- 5.6% (% of dose/24h urine). Excretion of unchanged antipyrine decreased from 5.2 +/- 3.7 to 2.7 +/- 0.9% dose. The metabolite profile (ratio between the amounts of the various metabolites excreted) was not significantly different. 4. It is concluded that malnutrition decreases the rate of antipyrine metabolism, but it does not affect the three oxidative pathways differently.