Delays in neurological drug development in Japan

The lag in the approval and development of neurological drugs between Japan and other countries has been a major issue for patients with neurological diseases. The objective of this study was to analyze the factors contributing to the delay in the launching of neurological drugs in Japan.

We analyzed data from Japan and the US for the approval of 36 standard neurological drugs and examined the potential factors that may cause the delay of their launch.

Of the 36 standard neurological drugs, all of which were approved in the US, only 21 were introduced in Japan from June 1999 to April 2010, whereas the other 15, whose indications were Alzheimer disease, epilepsy, migraine, multiple sclerosis, and Parkinson disease, remained unapproved. The US led Japan in the number of introductions (20 versus 1), with introductions in Japan occurring at a median of 87 months after introductions in the US. Japan's review time of new drug applications (23 months) could not explain this lag. In 15 of the 21 approved drugs, the application data package included overseas data. The mean review time of these 15 drugs was significantly shorter than that of the other 6 drugs without overseas data. The maximum daily doses of 7 of the drugs were higher in the US than in Japan.

These results show that there is still a large gap between Japan and the US with regard to access to standard neurological drugs, despite several important reforms in the Japanese drug approval system.