Interpreting Pharmacogenetic Data in the Developing Neonate: The Challenge of Hitting a Moving Target

In a 2010 review in Clinical Pharmacology & Therapeutics, Nick Holford noted that in neonates and young infants, maturation of the organs responsible for drug clearance is a more important determinant of pharmacokinetics (PK) than is body size.(1) Here we review recent developments that provide new insights into how physiological and environmental changes associated with adaptation to extrauterine life affect the ontogeny of drug biotransformation and interpretation of genotype-phenotype relationships in newborns and infants.