What happened
Drug Channels, in a rerun of a post originally published in June 2026, highlighted new JAMA Health Forum research showing a sharp change in Medicare Part D formulary coverage for multiple sclerosis drugs in 2025. According to the piece, Part D plans had often preferred high-list, high-rebate branded MS drugs over lower-cost generics before the Inflation Reduction Act reshaped plan incentives. The article says 2025 formularies shifted to near-universal generic coverage, after years in which generic-only coverage remained very low even after the first generic was approved. Drug Channels ties that reversal to the IRA Part D redesign. Before 2024, plans paid just 15% of costs above the catastrophic threshold, while the federal government covered 80% through reinsurance and beneficiaries paid the remaining 5% coinsurance. The post also cites a 46brooklyn analysis of 2020 glatiramer acetate, generic Copaxone, that found plans paid $13,187 annually, at most 17% of total costs, for branded Copaxone versus $21,226 for the generic, a difference of $8,039.
Why it matters
The cleanest read is that the IRA fixed a very specific Part D distortion in at least one specialty category. Drug Channels’ framing is straightforward: when plans had limited exposure in catastrophic coverage, high-list-price brands with rebates could be economically rational for the plan even if they were not the lowest-cost option for the system. Once the redesign increased plan liability and eliminated the 5% beneficiary coinsurance starting in 2024, plans had more reason to focus on net drug spending. In MS, that appears to have produced exactly the behavioral change policymakers were looking for.
Not a simple win. Patients, according to Drug Channels, got narrower formularies, higher upfront costs, and “way more taxpayer dollars spent than expected.” That tradeoff matters for payers and investors. It suggests the IRA can correct one incentive problem while creating pressure elsewhere in benefit design and public spending. The likely next question is whether this MS pattern extends beyond the four drugs tracked in the research, or whether, as Drug Channels notes, this “wasn’t the case for all drug classes.” For more on PBM economics, see RxPBM.ai. For drug pricing context, see RxInfo.ai.
