Merck (MSD outside of North America) has reported that it received a ruling in favour of the company from the US District Court for the Northern District of West Virginia in a patent infringement suit against Viatris linked to sitagliptin.

Sitagliptin is an active ingredient in the Januvia, Janumet and Janumet XR therapies.

The suit involved two Merck patents. The first is for the dihydrogen phosphate salt of sitagliptin. It will expire on 24 November 2026, and the paediatric exclusivity lasts until 24 May 2027.

Merck’s second patent covers the co-formulation of sitagliptin and metformin present in Janumet. It is expected to expire on 21 January 2029, with paediatric exclusivity lasting until 21 July 2029.

Under these patents, Merck filed infringement actions against Viatris, which claimed non-infringement and/or invalidity.

Viatris is seeking approval from the US Food and Drug Administration (FDA) to market Januvia and Janumet’s generic versions in the country.

According to the latest ruling, the court determined that both of the Merck patents at issue were legitimate and infringed.

The trial was presided over by Judge Irene Keeley, and the ruling is subject to appeal, the company noted.

Earlier, Viatris had challenged the salt patent’s validity in an Inter Parties Review before the US Patent Office.

Subsequently, the Patent Office issued a decision favouring Merck on 7 May last year, declaring that all challenged claims were genuine.

Viatris has filed an appeal against the decision to the Court of Appeals for the Federal Circuit, which is now pending.

Additionally, Merck has signed patent litigation settlement deals with various generic firms, permitting them to offer generic versions of Januvia and Janumet to the US market in May 2026, or before under specific conditions.

Merck has also permitted the sale of generic versions of Janumet XR to the market in July 2026 or before.

In June, the company received approval from the FDA for a pneumococcal 15-valent conjugate vaccine, Vaxneuvance, for children aged between six weeks and 17 years.