Cisapride disposition in neonates and infants: in vivo reflection of cytochrome P450 3A4 ontogeny

(1) In neonates and infants, cisapride absorption and metabolism to its primary metabolite, norcisapride, were developmentally dependent; (2) approximately 99% of cisapride CL/F in neonates and young infants was nonrenal in nature; (3) CL/F of cisapride in neonates and infants noted in this study was reduced compared with data from older children and adults, likely as a result of developmental reductions in CYP3A4 activity; (4) as reflected by the correlation between postconceptional age and lambda(z), a rapid increase in total CYP3A4 activity occurs in the first 3 months of life.