Approaches to Japanese dose evaluation in global drug development: factors that generate different dosages between Japan and the United States.

Drug development in Japan is shifting from a bridging strategy to a global strategy, and the number of multiregional trials in which Japan is included is increasing every year. The Japanese drug regulatory authority requires that data be collected in Japanese populations, and therefore dose-response studies of various drugs are frequently conducted in Japan. However, the current standard for adequate dose-finding processes may sometimes hinder the timely participation of Japan in these multiregional trials. We studied the development approaches and review patterns of 99 new molecular entities (NMEs) approved in 2003-2008 and have identified some common factors that result in differences in approved dosages in Japan as compared with other countries, such as dose-response study design, pharmacokinetics, and the timing of development. The findings of our research will serve as an initial information base on which to build an efficient global drug development strategy in Japan.