Abstracts

Rationale: Despite cost-effective generics, the median anti-seizure medications (ASM) cost per person nearly doubled from 2006 to 2021. The past decade, marked by the rise of generics and major events like the COVID-19 pandemic and high inflation presents a critical period for analyzing ASM price dynamics in the US.

Methods: We analyzed Medicare’s National Average Drug Acquisition Cost (NADAC) from Nov 2013 to July 2023 for prices of ASM. Prices were adjusted using the U.S. city average seasonally adjusted CPI data for medicinal drugs from the U.S. Bureau of Labor Statistics. The study examined the influence of the number of labelers per ASM and assessed the impact of the COVID-19 pandemic on ASM prices through correlational and interrupted time series analyses.


Results: We analyzed pricing data of 23 ASM (223 oral formulation types and strengths). The prices in this analysis reflect the cost per unit, such as per tablet or capsule. The average price of branded oral ASM increased from $8.71 (SD5.9) to $15.45 (SD10.7) between 2013-16 and 2020-23. Conversely, the price of generic oral medications declined from $1.39 (SD1.8) to $1.25 (SD1.68) over the same period (Fig 1A; Table 1). The mean price difference between branded and generic ASMs widened from 1452.39% in 2013-16 to 3419.36% in 2020-23 (Table 1). From 2013-16 to 2020-23, the share of generic ASM priced below $0.25 rose from 38.9% to 43.6%, while branded ASM priced above $20 increased from 9.09% to 27.2% (Fig 1B). For matched ASM formulations, the proportion of ASMs with a price difference > 1000% & < 10000% rose from 34.29% in 2013-16 to 43.28% in 2020-23. Formulations with a price difference greater than 10,000% increased from 17% to 20.9% over the same period (Fig 1D,1E). A consistent pattern emerged showing higher prices for individual branded ASMs compared to generics (Fig 1C, 1D, 1E; Table 1).



Each additional generic labeler decreased generic ASM prices by 5.45% (p=0.001) while increasing branded ASM prices by 2.46% (p< 0.001), across 17 brand ASM (86 variations). We analyzed the price impact on six branded ASMs (20 formulations) after losing market exclusivity. Within six months of generic entry, brand prices increased by 3.63% (p=0.004). Following the onset of COVID-19 in late 2019, the average monthly price of 17 branded medications (87 variants) rose by 24.4% (p< 0.001), while 18 generics (106 variants) fell by 23.1% (p< 0.001). Branded ASM prices continued to rise throughout the pandemic. Excluded from the main analysis, nasal ($305.6) and rectal ($268.6) seizure rescue medications were the most expensive ASM.


Conclusions: Our analysis of 23 antiepileptic medications from 2013 to 2023 showed an increase in branded ASM prices and a slight decrease in generic prices. The price gap between branded and generic ASMs significantly widened, with more generics priced below $0.25 and more high-priced branded formulations. Factors like additional generic labelers and COVID-19 disruptions underscore the urgency of strategic interventions in drug pricing policies.


Funding: This study received no funding.