Table 2

Examples of some alterations in hepatic metabolising enzymes with agea

Metabolizing enzymeAge-related alteration
CYP3A7High prenatally, low in adults.
CYP3A4Weak/absent prenatally, low in neonates/infants (40% of adults at age one month); high in adults.
CYP3A5More commonly expressed in children and adolescents than adults.
CYP1A2Low pre-natally, low in neonates/infants rising to adult levels (around age 3 years).
CYP2E1Low prenatally, rising after birth to adult levels (from age 1 year onwards).
Microsomal epoxide hydrolaseSimilar or lower level prenatally compared with adults.
N-acetyltransferaseLower in infants (1–2 years) than adults.
GlucuronidationExtremely low prenatally, lower in infants than adults.
SULT1A3Higher prenatally than in adults.
SULT1A1Lower prenatally than in adults.
  • a Adapted from Refs. 2 , 29 .