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Clin Pharmacol Ther. 1979 Apr;25(4):447-53.

Caffeine metabolism in the newborn.


The concentrations of caffeine and metabolites in urine have been examined as a function of age to explore the remarkably slow elimination of caffeine by human infants. Urine samples were obtained from 3 adults and 10 infants aged 8 days to 8 months during therapeutic treatment with caffeine. A high-performance liquid chromatographic (HPLC) procedure involving reversed-phase partition chromatography was developed to separate caffeine and 13 of its metabolites. During the first month of life, caffeine accounted for more than 85% of the identifiable products in urine. Caffeine remained the predominant component for the first 3 months, but its percentage decreased gradually to the adult value of less than 2% by the age of 7 to 9 months. This change reflected increasing metabolite production, not decreasing urinary caffeine concentration. The adult metabolite pattern of partially demethylated xanthines and urates was attained by 7 to 9 months. The data indicate that the 4-day plasma t1/2 of caffeine characteristic of the newborn depends in large part on slow urinary excretion of unchanged drug since there is little or no metabolism. Subsequent decrease in the t1/2 to about 4 hr by the age of 8 months correlates closely with the rise in metabolite production.

[Indexed for MEDLINE]

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