A working paper from the Eira Initiative examines data on pharmaceutical innovation. The author, Professor Erika Lietzan, finds that the evergreening narrative (which alleges companies patent revisions to drugs to prolong intellectual property protection) is conceptually flawed, misrepresents how patents and exclusivity intersect with drug approval frameworks, and risks misleading policymakers into enacting measures that would punish innovation to the detriment of patients.
For more than two decades, pharmaceutical companies have faced allegations of "evergreening" -- making minor changes to existing drugs in order to delay generic competition. These claims have fueled proposals to weaken patent rights.
The paper argues the evidence does not support the evergreening narrative. The research points to a dynamic innovation process in which incremental improvements to existing medicines continue alongside eventual generic entry, which typically occurs 12 to 14 years after FDA approval.
The full article is openly available on SSRN via this link.
To note, the working paper will also become part of the forthcoming book Bringing Medicines to Life: How Intellectual Property Enables Innovation in the Life Sciences (eds. Jonathan M. Barnett and Bowman Heiden), Cambridge University Press, slated for release later in 2026.