TABLE 4

Ontogeny of CYP3A, CYP2C, and CYP2J subfamilies in human GIT

P450 EnzymesQuantityExpression/ActivityNotes
FetusNeonatesPediatric Population
CYP3A4mRNA+ (Miki et al., 2005; Betts et al., 2015)<x (Miki et al., 2005; Betts et al., 2015)+ (Chen et al., 2015)+ (Fakhoury et al., 2005; Chen et al., 2015)Higher expression levels in fetus compared with adults
Increase during the first 3 mo after birth followed by a decrease with age to reach lower levels in older children or adults
Protein− (Johnson et al., 2001)+ (Johnson et al., 2001; Chen et al., 2015)+ (Johnson et al., 2001; Chen et al., 2015)Lower expression levels in neonates and pediatric population compared with adults; increase with age
Activity− (Johnson et al., 2001)+ (Johnson et al., 2001)+ (Johnson et al., 2001)Increase after birth with age
CYP3A5mRNA+ (Fakhoury et al., 2009)NANAIncrease with gestational age
CYP3A7mRNA+ (Betts et al., 2015)NA+ (Fakhoury et al., 2005)Lower expression levels compared with CYP3A4 and CYP3A5 in pediatric populations
Limited contribution of CYP3A7 in overall CYP3A-dependent enterocytic metabolism in children
CYP2C8 CYP2C9 CYP2C19Protein+ (Cizkova et al., 2014)NANAEquivalent to adult expression levels during first or second trimester
  • −, absent; NA, not assessed; +, present.