In the District of Delaware, Judge Leonard Stark recently issued a final judgment and permanent injunction in Cadence Pharms., Inc. v. Exela Pharma. Scis., LLC, No 11-733, 2013 U.S. Dist. LEXIS 166097 (D. Del. Nov. 14, 2013), which prevents defendant Exela Pharmaceutical, Inc. from manufacturing its generic version of OFIRMEV®, an injectable liquid acetaminophen composition.  Thereafter, Exela’s motion to reconsider was denied on December 27, 2013, and barring a contrary decision from the Federal Circuit, Exela will be enjoined from producing its generic formulation until June 6, 2021.

After conducting a seven-day bench trial, the court rejected Exela’s anticipation and obviousness argument and determined that Exela literally infringed U.S. Patent No. 6,028,222 (directed to a formulation of liquid acetaminophen) and infringed under the doctrine of equivalents U.S. Patent No. 6,992,218 (directed to a method for making liquid acetaminophen).

As to the ʼ222 patent, claim 1 requires an “aqueous medium” that contains “a buffering agent.”  The court rejected Exela’s arguments that the sodium ascorbate in its ANDA product was not a buffering agent because it did not sufficiently “help” resist a change in pH.  The court was persuaded by Cadence’s expert, who presented titration experiments showing that sodium ascorbate resisted a change in pH.  Meanwhile, Exela presented no laboratory tests in support of its argument or to rebut the results of Cadence’s titration experiments.

Claim 1 of the ʼ222 patent also required a “free radical scavenger,” and Cadence argued that this claim was satisfied through Exela’s use of mannitol.  The court agreed and found that Exela had waived any argument to the contrary, as it did not contest this argument prior to trial.  Moreover, Exela’s own expert report identified mannitol as a “free radical scavenger/antagonist.”

And although Cadence was unable to prove literal infringement as to the four asserted claims in the ʼ218 patent, it did prevail as to these claims under the doctrine of equivalents.  Indeed, the court had construed claim 1 of the ʼ218 patent as requiring the 2.0 ppm dissolved oxygen threshold to be met only after to the addition of acetaminophen, but Exela’s ANDA process showed that it met this threshold prior to the addition of acetaminophen.  The court found this to be a distinction without a difference, however.  Importantly, the court relied on testimony from Exela’s formulation scientist who testified that the ANDA product showed “no substantial differences” between the process in which acetaminophen is added before reducing the oxygen content of the formulation to below 2.0 ppm and a process in which acetaminophen is added after reducing the oxygen content to below 2.0 ppm.

In sum, this case highlights the potential value of hiring an expert to conduct experiments, the importance of crafting a coherent litigation strategy early in discovery, and assuring that all expert submissions and testimony support the arguments presented during trial.