ABSTRACT
Drug metabolism was defined previously as that part of the intermediary metabolism which is not related to the formation of ATP. This was generally accepted in spite of the fact that the various reactions of different phases of drug metabolism are ATP-consuming processes. This definition cannot be maintained anymore. It has turned out that several DME participate in intermediary metabolism pathways and their regulation is in accordance with the control of metabolism especially at the level of gene expression. Thus, there is a strong interrelationship between biotransformation and intermediary metabolism, which influences signal transduction through the metabolism of the signal molecules.
