These proceedings provide a general update in an important area of clinical pharmacology; describing how individual subjects vary in their response to drugs and how this information can be used to optimise drug dosing in disease. These proceedings cover areas such as the relevance of studies at various stages of drug development, in optimising drug dosing, the role that pharmacokinetics and pharmacodynamics play and how molecular biology has an increasingly important role in this area. As examples of how these influences may play a role, consideration is given to how drug dosing is optimised in various diseases such as cancer, psychiatric and cardiovascular disease, as well as considering the role that age may play in predicting drug dose. The major theme of this volume is that choosing the optimal dose of a drug has never been more important as risk and benefits must be carefully assessed. There are a series of underlying principles which help determine the optimal dose, and these are dealt with in a systematic manner, using relevant disease states to illustrate these principles.