U.S. District Court Rules In Favor of Merck in Sitagliptin Phosphate Patent Lawsuit

Merck, known as MSD outside of the United States and Canada, announced that the U.S. District Court for the Northern District of West Virginia ruled in favor of the company in a patent infringement suit against Viatris related to sitagliptin, an active ingredient in JANUVIA, JANUMET and JANUMET XR. The Court found that both Merck patents at issue were valid and infringed. The decision is subject to appeal.

Two Merck patents were involved in the suit. The first, U.S. Patent No. 7,326,708, covers the dihydrogen phosphate salt of sitagliptin and is set to expire on Nov. 24, 2026, with pediatric exclusivity extending to May 24, 2027. The second, U.S. Patent No. 8,414,921, covers the co-formulation of sitagliptin and metformin found in JANUMET and is set to expire Jan. 21, 2029, with pediatric exclusivity extending to July 21, 2029. Merck had filed infringement actions against Viatris under both patents, for which Viatris alleged non-infringement and/or invalidity.

Viatris is seeking U.S. Food and Drug Administration approval to market generic versions of JANUVIA and JANUMET in the U.S.

Viatris had previously challenged validity of the salt patent in an Inter Parties Review before the U.S. Patent Office. On May 7, 2021, the Patent Office issued a decision in Merck’s favor, finding all challenged claims valid. Viatris has appealed that decision to the Court of Appeals for the Federal Circuit, which is pending.

In addition, Merck has entered into patent litigation settlement agreements with multiple generic companies, allowing them to bring their generic versions of JANUVIA and JANUMET to the market in the U.S. in May 2026 or earlier under certain circumstances, and their generic versions of JANUMET XR to the market in July 2026 or earlier under certain circumstances.

Judge Irene Keeley presided over the trial. Merck was represented by the law firm of Williams & Connolly LLP.