Merck & Co., after settling with nearly two dozen drugmakers aiming to launch generics of its blockbuster Type 2 diabetes med Januvia, has successfully parried a Viatris patent assault in court.

A U.S. District Court in West Virginia sided with the New Jersey-based drugmaker over intellectual property challenges tied to sitagliptin, which is an active ingredient in Januvia and its offshoots Janumet and Janumet XR. The court found both Merck patents involved in the feud were valid and infringed, the company said in a release Thursday. Viatris still has the option to appeal the decision.

The patents in the case cover the dihydrogen phosphate salt of sitagliptin and the co-formulation of sitagliptin and metformin found in Janumet, Merck said. They provide intellectual property protections until 2027 and 2029, respectively.

Like many other generic drugmakers, Viatris is angling to market U.S. generics of the big-selling diabetes medicines. The pair ranked as Merck’s third best-selling drugs last year with total 2021 sales of about $5.3 billion.

But unlike the other generic companies, Viatris has opted against a patent settlement and instead took its arguments to trial.

Earlier this year, Merck said Januvia was set to lose U.S. exclusivity in January 2023. But Merck cautioned that if its 2027 "salt/polymorph patent" is upheld, that "would preclude generic manufacturers from making sitagliptin phosphate salt and polymorphic forms until 2027."

That means with the latest decision, Merck could have secured itself several more years of lucrative exclusivity for the medicine, subject to any appeals.

Whenever the Merck diabetes drugs lose exclusivity, the drugmaker expects sales to drop "substantially" following generic launches. The company has inked at least 21 settlements with generics companies allowing them to launch in May 2026 or earlier "under certain circumstances."