Study: Add-on patents have tripled, keeping drug prices high

A study published in JAMA has measured how far drugmakers expanded patent protection over three decades: the average number of patents per small-molecule drug more than tripled between 1990 and 2019. The growth came mostly from add-on filings that do not cover a drug's active ingredient and that, together, can hold back cheaper generics.

From 2.1 patents to 6.9

The research, led by S. Sean Tu of the University of Alabama, examined small-molecule drugs approved by the FDA and the patents filed on them. Medicines approved in 1990 carried an average of 2.1 patents; for those approved in 2019 the figure had reached 6.9.

Most of that increase came from what the authors call nonprimary patents, covering minor changes to a drug's non-active ingredients, new ways of using an existing medicine, or the design of delivery devices such as auto-injectors. Between 1990 and 2019 the FDA approved 1,981 small-molecule drugs, which together accounted for 10,940 patents. Nonprimary patents made up 84 percent of the total.

Patent thickets and longer exclusivity

Those extra filings form what researchers call a patent thicket: a dense set of overlapping claims that can make it harder for generic manufacturers to bring a competing version to market. Over the study period, the time a drug spent under patent rose from an average of two years in 1990 to 6.1 years in 2019.

Patent protection determines how long a brand-name firm can charge monopoly prices, the authors note, so the growth of nonprimary patents can restrict price competition. Inflation-adjusted US spending on prescription drugs per person rose from $291 in 1990 to $1,084 in 2019, per a Peterson-KFF analysis, and a Commonwealth Fund study earlier this year found Americans spend nearly twice as much on medicines as the average of other high-income countries.

Limits and proposed reforms

The study has a key limitation: it did not directly measure delays to generic drugs. Drugmakers often argue that additional patents do not hold up generics, but Tu's team notes that the examples usually cited involve medicines approved before 2010, when patent thickets were smaller than today. The five-year follow-up also probably understates current thickets, since patent activity now extends up to nine years after FDA approval.

The authors call for tougher scrutiny by the US Patent and Trademark Office (USPTO), laws limiting minor add-on patents, and the power for courts to force companies found to have abused patents to give back profits. Without such changes, they write, patent thickets will likely entrench exclusivity periods disconnected from genuine therapeutic innovation and keep delaying generic entry.