The U.S. Court of Appeals for the Federal Circuit recently upheld a district court ruling regarding the generic version of the ZTlido topical pain patch. The dispute centered on patent infringement allegations brought by Scilex Pharmaceuticals, which holds an exclusive license for the lidocaine patch technology. Scilex argued that the generic product developed by Aveva Drug Delivery Systems infringed on its patent claims under the doctrine of equivalents.
At the core of the case was the interpretation of the term dissolving agent. Scilex contended that the dissolving agent served only to keep lidocaine in a dissolved state within the patch. However, the district court disagreed after a four-day bench trial. It found that a person of ordinary skill in the art would recognize that the agent serves two distinct purposes: dissolving the lidocaine and preventing it from crystallizing during the manufacturing process.
The appellate panel confirmed the lower court's construction of the patent claims. The court noted that the patent specification consistently describes the use of an organic acid and a polyalcohol combination to perform the dissolution. The court stated that n-heptane, the solvent used in Aveva’s product, does not act as a functional equivalent to the specific two-component agent claimed in the Scilex patents.
Because the court affirmed the claim construction, it did not need to address additional arguments regarding prosecution history estoppel or claim vitiation. This decision serves as a significant outcome for Aveva, as the court effectively closed the door on the infringement claims brought by the patent holders. The ruling clarifies the functional requirements for dissolving agents in this specific category of lidocaine patch technology.