Which of the following differences during the neonatal and early infancy period has the greatest impact on drug disposition?
a) Decreased total body water
b) Decreased fat content
c) Decreased total body protein composition
d) Decreased plasma binding proteins
Answer d.
Plasma binding protein levels, primarily albumin and α1-acid glycoprotein, are diminished at birth and during early infancy resulting in an increased apparent volume of distribution for highly protein-bound drugs. Total body water is actually increased in the neonatal period. Developmental changes in fat and protein composition during infancy have not been shown to have a significant impact on drug disposition.