Glomerular development newborn

NRC 1993 Vieira et al. 1996). Whether differences in xenobiotic metabolism make the child more or less suseeptible also depends on whether the relevant enzymes are involved in activation of the parent compound to its toxic form or in detoxification. There may also be differences in excretion, particularly in the newborn who has a low glomerular filtration rate and has not developed efficient tubular secretion and resorption capacities (Altman and Dittmer 1974 NRC 1993 West et al. 1948). Children and adults may differ in their capacity to repair damage Irom chemical insults. Children also have a longer lifetime in which to express damage Irom chemicals this potential is particularly relevant to cancer. 

Age-related alteration of renal function is a very important factor in selecting the dose regimen. Renal function in newborns is incompletely developed. Neonatal renal plasma flow and glomerular filtration rates (normalized for body surface) are only 30-40% of those of adults. The half-life of penicillin G is 3.2 h in newborns (up to 6 days of age) and 1.4 h in infants (14 days of age or older), whereas in older children and adults, it is about 0.5 h. The mean half-life of gentamicin is about 5h in newborns under 1 week of age and about 3 h in infants 1-4 weeks of age. The half-life of gentamicin in older infants and adults is approximately 2 h. Thus, drugs that depend on renal excretion as the principal mode of elimination would be expected to have a longer residence time in infants. 

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