First-pass and systemic metabolism of cytochrome P450 3A substrates in neonates, infants, and children
Growth and development affect the metabolism of drugs administered to neonates, infants, and children.
- Brussee, J.M.
- 04 december 2018
- Thesis in Leiden Repository
Growth and development affect the metabolism of drugs administered to neonates, infants, and children. Research in this thesis focused on the metabolism by cytochrome P450 (CYP) 3A enzymes, aiming to predict CYP3A-mediated clearance in neonates, infants, and children, by development of pediatric (physiological) population pharmacokinetic models. CYP3A-mediated systemic metabolism of midazolam in critically ill pediatric patients was found to be impacted by body weight, critical illness, and inflammation. The developed model was subsequently found to accurately predict clearance in postoperative children or critically ill patients. Furthermore, advanced physiological modelling methods were applied to distinguish between first-pass and systemic CYP3A-mediated metabolism to elucidate the role of intestinal and hepatic CYP3A in neonates and children covering the whole pediatric age range. Lastly, it was described when a pediatric covariate function for CYP3A-mediated midazolam clearance could be applied to scale plasma clearance of other CYP3A substrates in the pediatric population. This work will significantly improve CYP3A-mediated clearance predictions in neonates, infants, and children, which will ultimately lead to rational support for pediatric doses of CYP3A substrates in first-in-child studies during drug development and for pediatric dose recommendations for CYP3A substrates in clinical practice.