[The history of drug reevaluation in Japan]

The drug reevaluation system was established to review the quality, efficacy and safety of drugs approved in the past based on current medical and pharmaceutical scientific standards. There have been three reevaluations of ethical drugs in Japan implemented according to the approved dates. The first reevaluation started in 1971 and finished in 1995 for the drugs that were approved up until September 1967. The second reevaluation started in 1984 and finished in 1996 for the drugs that were approved between October 1967 and March 1980. The new reevaluation system for all drugs regardless of the approval date consists of periodic reevaluation and Ad Hoc reevaluation. This system started in 1988 and has continued up to the present. Periodic reevaluation is a system where the efficacy and safety of drugs of all therapeutic categories are reviewed every five years based on literature screening. However, this system is currently suspended. Ad Hoc reevaluation is used to supplement periodic reevaluation and is performed at the onset of an emergency or when an entire therapeutic category becomes roblematic. In the second reevaluation and new reevaluation system, it is harder to judge which products must be reevaluated than in the first reevaluation for all drugs. In addition, the quality reevaluation for oral solid formulations based on dissolution studies started in February in 1997 and is almost finished.