OBJECTIVES

Antiepileptic drugs (AEDs) constitutes a significant portion of the direct cost imposed by epilepsy and other chronic neurologic disease treatment. We aimed to measure AEDs trends in utilization, expenditure and prices per prescription, and analyze the market share competition.

METHODS

A retrospective, descriptive analysis was conducted using the National Medicaid pharmacy claims database from 1991 to 2018. This study included three generations of AEDs: phenytoin, clonazepam, gabapentin, and lacosamide, etc. Annual trends of number of prescriptions, reimbursement expenditures, and price per prescription were calculated for each generation of AEDs. All expenditures were inflated to 2018 US dollars using the medical services component of the Consumer Price Index.

RESULTS

The total reimbursement for AEDs increased rapidly by 522.5% from $0.5 billion in 1991 to $3.1 billion in 2018, peaking at $3.7 billion in 2004. During the same period, the average price per prescription increased from $53.1 in 1991 to $85.85 in 2018, peaking at $122.9 in 2004, and the total number of prescriptions increased from 9.4 million in 1991 to 36.1 million in 2018, an increase of 285.4%. The 1^st generation AEDs prescription number declined from 2004, whereas the 2^nd generation AEDs prescriptions rose from 8.9 million in 2004 to 26.7 million in 2018, which was 74.0% of the total AEDs prescription in 2018. The 3^rd generation AEDs accounted for only 2.6% of the total prescription for AEDs in 2018 but 44.2% of the total reimbursement in the same year due to rapid increase in price from $536.9 in 2009 to $1467.8 in 2018.

CONCLUSIONS

Medicaid expenditure and the total number of prescriptions for AEDs increased substantially over time, which might be due to off-label use, new indications, and use for adjunct therapy. The 1^st generation AEDs were gradually replaced by the 2^nd and 3^rd generations AEDs in drug utilization.