Pharmaceutical companies have built dense thickets of patents around individual drugs to block cheaper generics and protect billions in revenue, according to a study published Tuesday in the journal Health Affairs.
Researchers examined 15 top-selling drugs and found an average of 74 patents filed on each one. The blood thinner Xarelto led the group with 125 patents. The diabetes drug Januvia carried 71.
The strategy, known in the industry as "evergreening," works by layering new patents on minor changes to a drug, such as a new formulation, dosing schedule, or delivery method. Each patent adds another legal hurdle for generic manufacturers trying to enter the market.
"The patent system is being used to extend monopolies, not to reward genuine innovation," said Robin Feldman, a law professor at UC Hastings and one of the study's authors. "Consumers pay the price at the pharmacy counter."
The study found that 78 percent of the patents on the drugs reviewed were for changes rather than the active ingredient itself. Many covered things like the color of a pill or how a patient takes the medication.
Brand-name drugs enjoy market exclusivity for years after launch. Generic competition typically cuts prices by 80 percent or more once it arrives. Delaying that competition by even a few months can be worth hundreds of millions of dollars to a manufacturer.
The findings arrive as Congress weighs legislation to curb prescription drug costs. A bipartisan bill introduced last year would cap out-of-pocket spending for Medicare recipients and allow the government to negotiate prices on certain drugs.
The pharmaceutical industry has pushed back hard against such proposals. Lobbying groups argue that strong patent protections fund the research and development that produces new treatments. The industry spent $306 million on lobbying in 2019, according to the Center for Responsive Politics.
Critics say the patent stacks rarely reflect meaningful advances. The study's authors pointed to AbbVie's Humira, the world's best-selling drug, which has more than 100 patents protecting it in the U.S. and no generic competitor until 2023, despite the drug launching in 2002.
"This is not about protecting invention," Feldman said. "It's about protecting profits."
The study's authors called for reforms, including tighter standards for what qualifies as a patentable improvement and limits on how many patents a single drug can hold.
