Which bodily change contributes to differences in drug distribution in neonates compared to adults?

The correct answer relates to the higher body water composition found in neonates compared to adults. Neonates have a significantly higher percentage of body water, typically around 75-80%, compared to adults, who have around 50-60% body water composition.

This increased body water affects the distribution of water-soluble drugs within the body. When a drug is administered to a neonate, it can distribute more widely due to the larger volume of water in which it can dissolve. Consequently, this can lead to differences in the drug's concentration in the bloodstream and its overall effect, requiring careful dosing considerations to avoid underdosing or overdosing.

Liver function, metabolic rate, and fat stores do play roles in drug pharmacokinetics as well, but the most significant difference in drug distribution for neonates hinges on their unique body composition, particularly their higher water content. This factor fundamentally influences how drugs are absorbed, distributed, and eliminated, which is essential to consider in pediatric pharmacotherapy.