Urinary recovery of caffeine and its metabolites in healthy African children

Abstract

Consumption of caffeine containing products is very popular in African children, particularly during ill health in the belief that caffeine promotes good health. This study aims to define the metabolism of caffeine, which takes place in the liver in a group of healthy Nigerian children. About lOOmg of caffeine was ingested after an overnight fast. Urine was collected before caffeine ingestion and over 12-hour periods for 36 hours in 13 healthy Nigerian children. The percentage of caffeine and metabolites recovered in urine was determined by high performance liquid chromatography. The total urinary caffeine and metabolites recovered over the 36-hour sampling period was 63.6%, with only 0.4% of the caffeine dose ingested recovered as unchanged caffeine during the same period. Insignificant amounts of 3,7- dimethyluric acid (0.2%), 3-methyluric acid (0.3%) and 1,3,7- dimethyluric acid (0.4) were recovered in the 36hour urine sample. This study also found that the N3-dcmcthylation pathway was the principal pathway of caffeine metabolism accounting for 83.3% of the total metabolites recovered while C8-hydroxylation accounted for only 0.6% of metabolites recovered. The pattern of urinary metabolites recovered suggested that N3-demethylation is the principal pathway of caffeine metabolism in healthy African children and that small amounts of unchanged caffeine, as well as 3,7-dimethyluric acid, 3-methyluric acid and 1,3,7-dimethyluric acid were recovered during the sampling period.