A study published Monday in JAMA quantifies what patients, pharmacists and regulators have long suspected: the patent wall around a typical prescription drug has grown steadily thicker, mostly for reasons unrelated to better medicine.
Researchers led by S. Sean Tu, an expert in drug and patent law at the University of Alabama, tracked every patent associated with small-molecule drugs approved by the FDA between 1990 and 2019. A drug approved in 1990 carried an average of 2.1 patents; by 2019 that figure was 6.9. Over the same period, the average time a drug spent under patent protection rose from about two years to 6.1 years.
The growth came overwhelmingly from "nonprimary" patents — claims that are not about a drug's active ingredient but about secondary details: tweaks to inactive ingredients, new ways of using an existing molecule, or the design of a delivery device such as an auto-injector. Stacked together, they form what the literature calls a "patent thicket," a legal maze that delays cheaper generics without delivering a clinical advance.
The economics are blunt. Patent protection is what lets a brand manufacturer charge monopoly prices, so every extra year of exclusivity is an extra year of spending for patients and insurers. The authors note their figures likely understate the problem: patent activity now stretches up to nine years past FDA approval, while their analysis stopped at a five-year follow-up window.
One limitation is baked into the data — the FDA does not systematically list patents for biologics, so the study covers only small-molecule drugs. The policy implication is nonetheless direct: proposals aimed at "evergreening," the practice of layering trivial patents onto an aging product, now have a fresh dataset to argue from.
