Urinary excretion of an uracilic metabolite from caffeine by rat, monkey and man.

Caffeine (C) metabolism has been studied in rat, monkey (Macaca cynomolgus) and man after oral administration of the compound. Eleven metabolites were quantified in urine; particular attention has been drawn to 4-amino [5-formyl methylamino]1,3-dimethyl uracil (ADMU) because of its structural analogies with 5-fluorouracil. The rat has been found to produce a much larger fraction of ADMU (about 30%) in respect to monkey an man (1-2%). The potential toxicological implications of this findings are discussed.