paediatric pharmacology

Paediatric pharmacology is the study of how drugs act in children and how they should be dosed for them. The old warning that a child is not just a small adult is the heart of the subject: a child's body handles and responds to drugs differently, and these differences change rapidly from a newborn to an infant to a school-age child to a teenager.

Many of the differences are about pharmacokinetics. A newborn's liver enzymes and kidneys are immature, so they clear some drugs much more slowly and can accumulate them to toxic levels, while older children may actually clear certain drugs faster than adults relative to their size. Body composition shifts too, with more body water early on, which changes how widely water-soluble drugs spread. Doses are therefore usually scaled to body weight or surface area, not simply guessed down from the adult dose.

Children are also vulnerable in ways adults are not, because drugs can disturb growth and development. A medicine may damage developing bones, teeth, or the brain, or interfere with growth, so some drugs that are safe for adults are avoided in the young. Practical problems matter as well, such as the need for liquid formulations, palatable taste, and avoiding tablets a small child cannot swallow.

A persistent honest difficulty is that children are studied far less than adults. Running trials in children raises ethical and practical hurdles, so a great deal of paediatric prescribing has historically been off-label, relying on extrapolation and experience. Regulators now actively require or encourage paediatric studies to shrink this evidence gap.