International harmonization of bioequivalence studies and issues shared in common.

In the course of a review of the current health insurance system in Japan, promotion of the use of generic products of lower price is expected in direction for minifying the drug costs which occupy about 20% thereof. However, the use of generic products has not increased so much as expected. One of the reasons to explain the fact might be that concerns exist about switchability from an innovator product to a generic product or among generic products because of bias in bioequivalence. Namely, hesitation about the difference in quality between generic products and innovator products, particularly in bioequivalence due to differences in the manufacturing process and pharmaceutical technology, exists among professionals in medical practice. The bioequivalence study to guarantee that a generic product is bioequivalent to an innovator product in terms of effectiveness and safety is most important in assuring the quality of generic products. There are various specifications and study methods to prove bioequivalence which differ slightly from one to another in different countries. We have investigated bioequivalence studies which are conducted in the major countries. Consequently, we clarified that bioequivalence studies are in international harmonization in terms of the major portions thereof. However, different conditions, e.g., selection of subjects, food effect, application of multiple dose study, and in vitro dissolution study, are still employed for the studies. Therefore, we consider that these differences constitute the topics to be reviewed in future.