Indexed on: 10 Jun '18Published on: 10 Jun '18Published in: Drug metabolism and disposition: the biological fate of chemicals
The induction of cytochrome P450 enzymes (CYPs) in response to drug treatment is a significant contributing factor to drug-drug interactions, which may reduce therapeutic efficacy and/or cause toxicity. As most studies on CYP induction are performed in adults, enzyme induction at neonatal, infant, and adolescent ages is not well understood. Previous work defined the postnatal ontogeny of drug-metabolizing CYPs in human and mouse livers; however, there are limited data on the ontogeny of the induction potential of each enzyme in response to drug treatment. Induction of CYPs at the neonatal age may also cause permanent alterations in CYP expression in adults. The goal of this study was to investigate the short-/long-term effects of phenytoin treatment on mRNA and protein expressions and enzyme activities of CYP2B10, 2C29, 3A11, and 3A16 at different ages during postnatal liver maturation in mice. Induction of mRNA immediately following phenytoin treatment appeared to depend on basal expression of the enzyme at a specific age. While neonatal mice showed the greatest fold-changes in CYP2B10, 2C29, and 3A11 mRNA expression following treatment, the levels of induced protein expression and enzymatic activity were much lower than that of induced levels in adults. The expression of fetal CYP3A16 was repressed by phenytoin treatment. Neonatal treatment with phenytoin did not permanently induce enzyme expression in adulthood. Taken together, our data suggest that inducibility of drug metabolizing CYPs is much lower in neonatal mice than it is in adults and neonatal induction by phenytoin is not permanent. The American Society for Pharmacology and Experimental Therapeutics.