A–Z of prescribing for children

It is commonly stated that children are not just small adults; yet, most paediatric medication doses are still calculated from studies in adults (O'Hara, 2016). A knowledge of physiological differences between children and adults is imperative to have a thorough understanding in differences in pharmacokinetics.

Unless administered intravenously, drugs need to cross semipermeable cell membranes before they finally reach the systemic circulation. There are many other ways in which drugs are administered by extravascular routes, such as via the gastrointestinal (GI) tract, topical or transdermal, and through the lungs being the most common routes (van den Anker et al, 2018). Most drugs in children are administered orally. The taste of medications is an important factor (see ‘T’ later in this series), as children will naturally reject bitter or foul-tasting medications. However, once successfully taken, drugs will enter the stomach and gastric pH needs to be considered (Figure 1).