Abstract
Significant changes in hepatic drug clearance occur in the transition from childhood to adulthood. These changes probably parallel the functional capacity of the hepatic cytochrome P-450 dependent mixed function oxidase (MFO) system. GH decreases hepatic MFO activity in animals and may act similarly in humans. Caffeine labelled with stable 13C has been shown to be a substrate for the MFO system. Five GH deficient children underwent CBT, with collections of expired air for 13CO2 enrichment analysis following ingestion of 13C-caffeine (3 mg/Kg) before, and 4-5 weeks following GH 0.1 u/Kg S.C. t.i.w. All children showed a decrease in % 13CO2 dose exhaled over 2 hours following GH administration:
Pre 9.1±1.5, Post 7.3±2.9 (p < .05, paired t-test) The CBT is a safe effective technique for the measurement of the hepatic MFO system. N-demethylation of caffeine is decreased by GH therapy in GH deficient children. The capacity for N-demethylation is highest in prepubertal children. This may partially correlate with changing patterns of GH release.
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Levitsky, L., Lambert, G., Schoeller, D. et al. 29 DECREASE IN CYTOCHROME P-450 DEPENDENT 3-N-DEMETHYLATION OF CAFFEINE MEASURED BY THE CAFFEINE 13CO2 BREATH TEST (CET) FOLLOWING GROWTH HORMONE THERAPY IN GROWTH HORMONE (GH) DEFICIENT CHILDREN. Pediatr Res 19, 608 (1985). https://doi.org/10.1203/00006450-198506000-00049
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DOI: https://doi.org/10.1203/00006450-198506000-00049