Pharmaceutical companies are taking advantage of the drug patent system to keep prices of essential medications high, according to a new report — and that includes blockbuster weight-loss drugs and other expensive medications set for government price negotiations this year.

The new findings illustrate how drugmakers file dozens of patents to cover minor modifications in the same drug in order to extend their market exclusivity, delaying the entry of cheaper generic medications and generating billions of dollars in extra revenue.

“We want to expose how the patent system has become a tool to drive the business model and financial gain,” said Tahir Amin, CEO of Initiative for Medicines, Access & Knowledge, a research and policy advocacy organization focused on patent laws that published the report. “It’s a corruption of the patent system.”

A standard drug patent lasts twenty years from the date it is first filed, though the time a drug company holds market exclusivity is often roughly half that, due to the lengthy regulatory approval process required before a drug can be sold. To compensate for regulatory delays, drug companies can request up to five years of additional protection thanks to the 1984 Hatch-Waxman Act — the same law that aimed to streamline the entry of generic drugs into the market.

Experts like Amin argue that drugmakers are abusing these extensions by filing hundreds of additional patents for anything from minor drug updates to particular manufacturing processes, thus prolonging their market monopoly. A 2023 study published in Yale Law and Policy Review found that of the 236 top-selling drugs, 91 percent that received patent extensions preserved their monopolies well past the expiration of their Hatch-Waxman extensions thanks to these add-on patents.

In their new report, Amin and his team examined the patent histories of four widely popular and pricey prescription drugs: the blood thinner Eliquis; the blockbuster weight-loss drug Wegovy; and two diabetes drugs, Ozempic and Rybelsus. All four medications have been chosen for price negotiations between Medicare and drugmakers — part of the 2022 Inflation Reduction Act that requires the government to negotiate lower prices of especially expensive and popular drugs directly with pharmaceutical companies. Millions of patients take Eliquis, Wegovy, Ozempic, and Rybelsus, costing the government’s public health care system billions of dollars annually.

Novo Nordisk, the powerful Danish pharmaceutical manufacturer behind Rybelsus, Ozempic, and Wegovy, owns two key patents for the drugs’ active ingredient, semaglutide, that were originally set to expire in March 2026.

However, the drugmaker received a five-year extension under the Hatch-Waxman Act on one of those patents, bumping the expiration date to December 2031. Over that five-year period, according to the report, the drugmaker is projected to earn an estimated $166 billion from the drugs — all of which have already benefited from billions of dollars of US taxpayer funding to develop the products.

On top of that, Novo Nordisk has been granted forty-nine follow-on patents that provide protection until 2042 — amounting to around sixteen years of extra patent protection overall.

The same goes for Eliquis, which received a Hatch-Waxman extension for a key patent on the drug’s active ingredient that was originally set to expire in September 2022. The drugmakers behind Eliquis, Bristol Myers Squibb and Pfizer, were also granted five add-on patents, the last of which is set to run out in November 2040 — providing about eighteen years of additional patent protections. Altogether, Bristol Myers Squibb and Pfizer are expected to make an additional $50 billion in profits by extending their monopoly, according to the report.

Critics argue that this is an abuse of the patent extension system.

“The abundant use of these secondary patents is explicitly counter to what Congress intended when crafting the Hatch-Waxman legislation,” Robin Feldman, a law professor at the University of California Law, San Francisco, and patent law expert, wrote in her 2023 study for Yale Law and Policy Review. In fact, Feldman notes, Congress stressed that secondary patents provide “less of an inventive contribution to society.”

The systematic abuses within the patent system must be addressed, said Amin, for the sake of patients and the US health care system.

“We need to revisit Hatch-Waxman, as it is out of date given how we know the pharmaceutical industry abuses the patent system today,” Amin said. “Essentially, we should end patent term extensions, at least for blockbuster drugs, and we would see generics much sooner.”