Doctrine of equivalents removes painkiller from German market: Grünenthal wins preliminary injunction on appeal

Context: The doctrine of equivalents (DoE), more commonly referred to as “doctrine of equivalence” in Europe, is a means of broadening the scope of a patent claim beyoind its literal meaning that courts apply only sparingly as there would otherwise be too much legal uncertainty. Nevertheless the DoE is regularly invoked, such as in a Unified Patent Court (UPC) case on which we reported yesterday (September 15, 2025 ip fray article).

What’s new: Litigation boutique Arnold Ruess just announced a landmark DoE-based victory in the Oberlandesgericht Düsseldorf (Dusseldorf Higher Regional Court). On Friday (September 12, 2025), firm client Grünenthal, a major player in the pain management market and maker of the Vimovo drug, obtained a preliminary injunction (PI) against Abdi Farma, a German subsidiary of Turkish generics maker Abdi Ibrahim, against a painkiller named Naproxen/Esomeprazol Abdi 500/20 mg (case no. I-2 U 60/25). The court below, the Landgericht Düsseldorf (Dusseldorf Regional Court), had denied a PI as it was not prepared to grant one on the DoE basis the plaintiff proposed. However, the regional court’s 8th Chamber for Commercial Litigation did grant Grünenthal two PIs over inaccurate product and package information as a result of representations Abdi made in the course of the patent PI proceedings. Separately, Grünenthal is enforcing its IP in Portugal and Norway against a product that Abdi makes for Sandoz, but with no injunction having issued thus far.

Direct impact: The German patent-in-suit, DE 602 37 087.6, has already expired, and a supplementary protection certificate (SPC), DE 12 2012 000 052.7, will do so on November 5, 2025. Therefore, the PI will only be short-lived, as in many time-to-market cases involving generics. On the fast track, the Dusseldorf Higher Regional Court decision marks the end of the road for the German proceedings apart from the (slower) main proceedings. The ultimate outcome could differ, though the most likely result is that the appeals court would reach the same conclusion and that the lower court would anticipate as much. As a result, Grünenthal will presumably be able to recover damages, though it would have had a far greater benefit from a PI in the first instance.

Wider ramifications: Regardless of how the timing of the decision relative to the impending expiration of the SPC limits its commercial value, there can be no doubt about the significance of this precedent. Since the Bundesgerichtshof (Federal Court of Justice of Germany) decided pemetrexed in 2016, this is the first time for a plaintiff to have prevailed in the Dusseldorf regional appeals court on a DoE basis.