Population modelling in drug development

In this paper we discuss the Vital role that population (hierarchical) mode lling can play within the drug development process. Specifically, populatio n pharmacokinetic/pharmacodynamic models can provide reliable predictions o f an individualized dose-exposure-response relationship. A predictive model of this kind can be used to simulate and hence design clinical trials, fin d initial dosage regimens satisfying an optimality criterion on the populat ion distribution of responses, and individualized regimens satisfying such a criterion conditional on individual features, such as sex, age, etc. Thro ughout we emphasize prediction and advocate mechanistic as opposed to empir ical modelling, and argue that the Bayesian approach is particularly natura l in this setting.