Trends in prescription of anti-seizure medications in Japan between 2018 and 2021: A retrospective study using the National Database Open Data Japan.

Purpose: This retrospective study aimed to analyze anti-seizure medication (ASM) prescription trends in Japan, particularly among older adults and women of childbearing age, to inform future treatment strategies and optimize ASM selection criteria.

Methods: Data were extracted from the National Database Open Data Japan for fiscal years (FY) 2018-2021, covering prescriptions across sex and 5-year age groups. We conducted data imputation for prescriptions under 1,000 units to maintain anonymity, calculated the estimated number of patients using standard adult maintenance doses, and adjusted for pediatric dosing using Augsberger's formula.

Results: Our analysis revealed a 7.6% increase in ASM usage, with a notable shift from older to newer ASMs, such as levetiracetam (LEV) and lamotrigine (LTG). LEV and LTG prescriptions increased by 26.7% and 15.0% from FY 2018 to FY 2021, respectively, whereas older ASMs such as phenytoin, declined. Sex-specific analysis showed a higher LTG prescription rate among women, especially in adolescent and young adult cohorts, where the female-to-male prescription ratio increased from 1.65 to 1.85. Valproate (VPA) and LEV accounted for 57.0% of ASM prescriptions in older adults. The number of inpatient LTG prescriptions was notably lower than that of outpatient LTG prescriptions across age groups. Pediatric use of generics was lower than that in other age groups.

Conclusion: This study revealed that newer ASMs are being used increasingly, with a significant proportion of VPA continuously prescribed among women of childbearing age. In older adults, VPA and LEV accounted for more than half of the ASM prescriptions. These findings are crucial for developing future treatment strategies and improving the ASM selection criteria.