[Application of population pharmacokinetic approach to clinical evaluation of anticancer agents]

Population pharmacokinetics deals with the typical profiles and the inter- and intra-individual variability in the target patient population to which the drug is applied. It also describes factors that can affect the inter-individual variability in pharmacokinetics, including physiological, pathological, genetic, and external factors. The sample population is the actual patients with a variety of backgrounds, which enables us to analyze the influences of several factors such as severity of illness, advanced age, childhood, and renal or hepatic dysfunction, and also to identify the special populations where dose adjustment is needed. Pharmacokinetic and pharmacodynamic information are useful to a rational dosage regimen. The findings obtained by the population pharmacokinetic and pharmacodynamic analysis, provide an advice about whether a dosage regimen should be individualized in all patients or in identified special populations, together with how to adjust the dose. The study design for population pharmacokinetic analysis is called "pharmacokinetic screen", where drug concentration data are collected from a large number of patients while only a few blood samples are taken from individual patients. The population pharmacokinetic approach is useful not only for establishing the rationale dosage regimen but also for international exchange of clinical data in the global drug development.