Introduction

The concept of individualized drug therapy has been a central focus in clinical pharmacology and medicine for many decades (1). In practice, there are two key elements concerning customized therapies: choice of the dosing regimen and/or the drug itself. Both of these factors contribute to personalized medicine. Despite its apparent simplicity, individualization of treatment is a daunting challenge due to molecular heterogeneity in human diseases and marked patient-to-patient and between-population differences in drug effects as well as therapeutic dose requirements.