[The 1998 domestic state of development of cognitive enhancers]

Recently, there is a great social problem that geriatric disorders, especially senile dementia, are growing rapidly with the increasing percentage of aged individuals in the total population. However, there is yet no drug that has reliable effects on senile dementia on the market. Therefore, society requires the development of new drugs that can support patients so that they can smoothly live their daily lives by themselves. In this study, we attempted to investigate the 1998 domestic state of development of cognitive enhancers by summarizing many publications and by gathering questionnaires from pharmaceutical, food, synthetic fiber and chemical manufacturing companies. There were 40 currently investigated cognitive enhancers in Japan as of the end of March, 1999 including 37 newly synthesized compounds and 3 new dosage forms or applications of additional effects. On the classification according to the mechanism of drug action, 12 of the investigated drugs are cholinomimetic agents, 12 are ameliorators of neuronal transmission, 1 is an intracellular mediative substance, 3 are neuropeptides, 2 are cerebral metabolic activators, 2 are cerebral circulation enhancers and 7 are neuronal cell protectors, and 1 is another type. For dementia of the Alzheimer's type, there are 1, 3, 10 and 2 drugs in prerecognition, phase late II, early II and I of clinical trials, respectively. For cerebrovascular dementia and cerebrovascular disease, there are 19 drugs being investigated. Seven of these compounds such as E2020 (donepedil HCl), DM-9384 (nefiracetam), TA-0910 (taltirelin), NS-3 (montirelin), TTC-909 (clinprost), DR-3305 (ebselen) and AVS (nicaraven) are at the prerecognition stage for marketing. It is important that effective cognitive enhancers will be supplied for clinical stage use as soon as possible.