A recent analysis led by Sean Tu of the University of Alabama School of Law suggests that a legal framework designed to make it easier for generic drugmakers to enter the market is now being used by brand-name pharmaceutical companies to maintain their exclusivity. The findings, published in Health Affairs Scholar in December 2025, highlight how serial litigation is used to delay competition and keep drug prices high.
Tu described the process faced by generic manufacturers: “I’m litigating. I think the litigation is done. And then I get sued again,” he said. “And I do the litigation. And I think the litigation is done. And I get sued again. And it’s really problematic when it’s these patents that are really the same.”
Julia Pike, global head of IP at Sandoz, a generics company, noted that this practice has become more common over the past decade or so as major pharmaceutical firms approach significant patent expirations that could impact their revenues. According to analysts at William Blair, drugs losing exclusivity accounted for over 30% of combined revenues from companies such as Bristol Myers Squibb, Pfizer, AstraZeneca, Novartis and Regeneron in 2024.
The strategy takes advantage of provisions in the Hatch-Waxman Act of 1984. Before this law was enacted, generic companies had to conduct their own clinical trials even if an original product had already been approved by the FDA. The act streamlined this process by allowing generics makers to file an Abbreviated New Drug Application (ANDA) with certifications regarding relevant patents.
If a brand-name manufacturer sues for patent infringement after an ANDA filing, there is an automatic 30-month stay on FDA approval while legal proceedings take place. Tu explained that initially most drugs only had one or two patents each and challenges often led to lower prices once generics entered the market.
However, since around 2010 there has been a sharp increase in continuation patents—patents similar or nearly identical to previous ones—which allow repeated lawsuits against generics attempting to launch competing products.
“If we stop competition, that’s a win for brand companies, right? That means that we’re going to have higher drug prices for longer periods of time,” Tu said. “How do I get less competitors? I make it riskier. I make it more expensive. I force them to come on the market later. All of that I can do through patents.”
Pike stated that each round of Hatch-Waxman litigation costs more than $6 million and described ongoing cases where Sandoz has faced multiple waves of lawsuits trying to bring generic drugs like Bimatoprost and Myrbetriq (mirabegron) to market.
She referred specifically to Astellas’ actions regarding Myrbetriq: “We’ve been in four waves of litigation on that case since 2011. And that case continues.” She called this “a textbook example of serial patent litigation,” but added: “It’s not an Astellas strategy. It’s a broader industry strategy.”
Astellas did not comment on these claims.
Pike also noted that defending such lawsuits can cost more than developing some drugs themselves: “Before you’ve even set foot in the U.S., you’re anticipating that the cost of developing that product is going to double just because of the first round of litigation.”
Tu emphasized his support for patents but questioned current practices: “People say, ‘oh, this guy doesn’t like patents.’ That’s not true. Patents are very effective at promoting innovation... But your patents shouldn’t last for forever. And we’re asking the patent system to do something now that it was never intended to do, which is extend monopoly power.”
