ABSTRACT
When designing drug dosage regimens for clinical use, one of the most important factors to be defined during drug development is how drugs are handled by the body, i.e. the pharmacokinetic parameters need to be characterised. Initial studies are typically performed in healthy subjects then, in later phases of drug development, studies are undertaken using patients with the underlying disease. Historically, there were limited opportunities for evaluating drug handling in infants and children and, consequently, paediatric drug dosage regimens were developed empirically from adult regimens by adjusting for weight or body surface area. Unfortunately, this approach fails to recognise age-related differences, both in drug handling and drug response, that might influence drug dosage requirements independently of “size”. The “population approach” allows drug handling to be studied in paediatric patients with a technique that is less invasive and, consequently, has fewer ethical and practical limitations than conventional methodologies.
