Neonate, drug metabolism

As with neonates, drug-metabolizing capacity in elderly subjects is also reduced in comparison with young adults for some compounds, such as benoxaprofen, propranolol, and... 

As with neonates, drug-metabolizing capacity in elderly subjects is also reduced in comparison with young adults for some compounds, such as benoxaprofen, propranolol and lignocaine. Other drugs such as isonazid and warfarin show a similar plasma half-life in elderly as in young adults. It seems that phase 1 metabolism is more likely to be affected in the elderly than phase 2 reactions. However, it... 

The activity of CYP3A isoenzymes in the human fetal liver is similar to that seen in adult liver microsomes. The fetal activity for CYP3A7 isoenzyme is unusual as most other fetal isoenzymes of CYP450 exhibit 5 to 40% of fhe adulf isoenzymes. Fetal and neonatal drug-metabolizing enzyme activities may differ from those in the adult. 

Neonate Immature kidney Immature drug metabolizing enzymes Risk of Cp rise if dose not adjusted... 

Table 5. Drug metabolism in the neonate, infant and child...

Another consideration for the neonate is whether or not the mother was receiving drugs (such as phenobarbital) that can induce early maturation of fetal hepatic enzymes. In this case, the ability of the neonate to metabolize certain drugs will be greater than expected, and one may see less therapeutic effect and lower plasma drug concentrations when the usual neonatal dose is given. 

Both in vitro and in vivo metabolic studies have shown that some drug metabolism occurs or can be induced in placental tissues (20). Further degradation of parent chloroquine that reaches the placenta would result in the appearance of less chloroquine and more of the nonpolar metabolites in the fetal or neonatal circulation. (17). 

Bickers DR, Dutta-Choudhury T, Mukhtar H. 1982. Epidermis A site of drug metabolism in neonatal rat skin. Studies on cytochrome P-450 content and mixed-function oxidase and epoxide hydrolase activity. Mol Pharmacol 21 239-247. 

Blake MJ, Castro F, Feeder JS, Kearns GF. Ontogeny of drug metabolizing enzymes in the neonate. Semin Fetal Neonatal Med 2005 10 123-38. 

Dotta A, Chukhlantseva N (2012) Ontogeny and drug metabolism in new borns. J Metern Fetal Neonatal Med 4 83-84... 

Age. The pharmacokinetic and pharmacodynamic effects of a drug can be influenced by age, and drug metabolism plays an important role in understanding the differences observed. Differences between the levels of metabolism enzymes for the fetal and neonatal (first 4 weeks postpartum) liver versus the adult liver have been observed in both animal and human studies (125). At birth, total CYP levels are approximately 30%of adult levels and glucuronidation activity is at 10-30% of adult levels. Interestingly, sulfotransferase activity in neonates seems to be comparable with that in adults. 

K. Yamauchi, and R. Kato (1988). Alteration of hepatic drug metabolizing activities and contents of cytochrome P-450 isozymes by neonatal monosodium glutamate treatment. Biochem. Pharmacol, yi, 1687-1691. 

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