Development of a new Japanese guideline on drug interaction for drug development and appropriate provision of information.

Drug interactions, in particular with concomitant drugs having a narrow therapeutic range, sometimes cause serious adverse drug reactions or attenuation of the therapeutic effect. Therefore, evaluation of the characteristics and severities of possible drug interactions in drug development is essential to understand such interactions to help prevent any potential risk for patients. In Japan, a regulatory document which was notified in 2001 to outline the basic principles of drug interaction studies during drug development was revised as a new guideline after 17 years to present general procedures that are currently considered scientifically valid. This article aims to present an overview of development process of the new Japanese guideline for investigating drug interactions and show the impact of implementating this guideline on drug interaction evaluations, thereby providing future perspectives of regulatory activities on drug interactions.