Drug Patent “Thickets” Are Keeping Generic Medicines Off the Market for Years

Americans already pay some of the world’s highest medical costs, but prescription drugs are a particularly serious source of financial strain. A new study suggests that the growing number of patents attached to individual medicines may be helping drugmakers delay generic competition and keep prices high.

The study was published Monday in the journal JAMA. Researchers found that the average number of patents associated with small-molecule drugs approved in the United States more than tripled—from 2.1 patents per drug in 1990 to 6.9 patents per drug in 2019.

How drug patent “thickets” delay generic competition

Much of this growth involved what researchers describe as “minor” patents. Rather than covering a drug’s active ingredient, these patents often involve changes to inactive ingredients, updates to how a medicine is used, or specialized delivery devices such as auto-injectors.

Individually, these patents may appear limited. Taken together, however, they can form a so-called patent thicket—a dense collection of overlapping patents that can make it more difficult for generic manufacturers to enter the market.

That delay can allow branded drugmakers to maintain high prices for longer periods, even when the additional patents do not represent major clinical advances.

Patent protections lasted longer in 2019 than in 1990

The study was led by S. Sean Tu, a drug and patent law expert at the University of Alabama. Tu and his colleagues found that the increase in patents per drug extended the average patent life of the medicines they examined from two years in 1990 to 6.1 years in 2019.

“Because patent protection typically determines the length of time a branded company can charge monopoly prices, the rapid growth of non-key patents could contribute to limited price competition that benefits patients and health systems by avoiding unnecessary expenses,” Tu and his colleagues wrote.

What the study examined

The researchers used public data to examine small-molecule drugs approved by the US Food and Drug Administration, along with the patents filed for those medicines. They categorized the patents associated with each drug and assessed how those patents affected the drug’s patent term.

The analysis focused on small-molecule drugs that received FDA approval between 1990 and 2019. Researchers tracked patents for five years after approval. The study did not examine other types of medicines, such as biological products.

The authors note that the findings may underestimate the current size of the patent thicket. Patent activity can now continue for as long as nine years after a drug receives FDA approval, compared with the five-year tracking period used in the study.