Clinical pharmacology of the perinatal period and early infancy.

A consistent body of data, acquired in the last 20 years, indicates that at birth most of the physiological variables regulating drug kinetics are immature, thus conditioning modified kinetic profiles in the neonate. The situation may be greatly complicated by the possible 'in utero' exposure to agents capable of altering the activity of liver and/or kidney excretory functions, and/or the presence of severe pathological conditions capable of significantly altering regional or general haemodynamics. The different variables mature at different rates depending on the gestational age and physiopathological conditions. A review of the available information on drug kinetics in the neonate and early infancy is presented here. Therapeutic drug monitoring appears to be the only possible way to assure a safer therapy for at-risk populations.