Correlation between prescription volumes of generic antiepileptic drugs and the number of clinical epileptologists across prefectural regions in Japan: A descriptive study using a national claims database

Although generic drugs are essential in reducing medical costs, their use in epilepsy therapy remains a subject of ongoing debate. In this study, we analysed prescription trends of generic drugs using data from the National Database of Health Insurance Claims and Specific Health Checkups (NDB) Open Data Japan. The number of generic drug prescriptions from 2017–2021 was extracted from the NDB Open Data Japan, with data for each medication stratified by prefectural region, sex, and age, allowing for the analysis of the impact of each factor. We analysed the correlation between the prescription volumes of generic antiseizure medications (ASMs) and the number of clinical epileptologists registered with the Japan Epilepsy Society per 100,000 population. In 2021, the prescription volume of generic ASMs was 49 %, whereas that for other pharmacological agents was between 70–80 %. Notably, for children < 15 years of age, generics made up approximately 20 % of prescriptions, which was significantly less than that in other age groups. Analysis by prefecture revealed a negative correlation between prescription volumes of ASMs and the number of clinical epileptologists across prefectural regions in Japan (R = −0.47, p < 0.01). Our findings indicate that the higher the proportion of clinical epileptologists in each prefecture, the lower the number of prescribed generic ASMs. Clinical epileptologists in Japan therefore prescribe antiseizure agents in accordance with the Japanese epilepsy treatment guidelines that do not recommend the use of generic agents. •Generic use in epilepsy therapy remains a subject of ongoing debate.•Prescription trends of generics were analysed using a claims database in Japan.•The use of antiepileptic generics is relatively low in Japan.•To reduce healthcare costs, the increase in generic prescribing is necessary.•Potential adverse effects of switching to generics in epilepsy should be considered.