The past, present and future of pharmacoepigenomics.

A significant number of instances of interindividual variability in drug response, where a clear phenotypic consequence is evident in the population, have not yet been associated with variations in gene sequence. Epigenetics, along with, for example, drug interactions and disease, provides answers to some of these inconsistencies. The role of epigenetics in drug response has just started to be perceived, but its impending influence on drug metabolism and disposition promises to be important. Research in this area can provide us with novel mechanisms for this variation and also with novel biomarkers that can be useful for understanding drug response, as well as for the development of new drugs and which can, in addition, constitute predictive biomarkers for today's and tomorrow's pharmacotherapy, yielding a substantial improvement in human health.