In the second part of her update series Agnes Kanneh considers general pharmacokinetic principles and their specific application in children

Pharmacokinetics denote the movement of drugs through the body over time, and addresses the absorption from the site of administration, distribution throughout the body, metabolism of the drug, and its elimination from the body. In everyday terms, it is viewed as what the body does to drugs after intake, regardless of the route of administration (McLeod 1999). The notion of the drug that is totally safe is a myth as no science can guarantee such a utopia and children feature highly in this note of caution. Indeed, the basic tenet in paediatric pharmacotherapeutics is ‘therapy without toxicity’. Therefore in child health care, practitioners have to weigh up the expected benefits against risks inherent in the drug in each circumstance.