Federal Circuit Clarifies What the “Product” Is In Para IV Infringement Litigation

The Federal Circuit recently issued an opinion that reminds us of the importance of being consistent in our statements to the FDA and in patent matters.  What matters for the sake of infringement analysis is the product specified in the ANDA filing.

The case, Sunovion Pharmaceuticals., Inc. v. Teva Pharmaceuticals USA, Inc. et al. (Fed. Cir, Sept. 2013) arose from a summary judgment decision that one of the co-defendants, Dr. Reddy’s Laboratories, Ltd. did not infringe Sunovion’s patent, US 6,444,673.  The patent covers the d-enantiomer of zopiclone, known as eszopiclone, which is the sleep-aid drug sold under the brand Lunesta®.  The patent claims the zopliclone molecule “or a pharmaceutically acceptable salt thereof, in the form of its dextrarotatory isomer and essentially free of its levorotatory isomer.”

The trial judge construed the phrase “essentially free of its levorotatory isomer” to mean containing less than 0.25% of the l-isomer.  The Federal Circuit agreed with this construction.  Noting that the term “essentially free” appeared only in the claims and was not defined in the specification, the Federal Circuit found support for this construction in a declaration filed during prosecution of the ‘673 patent by one of the inventors, who stated that the pure form of the d-isomer described in one of the examples contained lower than 0.25% of the l-isomer.  Sunovion had also relied on this declaration in an interference with another patent claiming an enantiomeric form of zopiclone.

In its original ANDA filing, Dr. Reddy’s had requested approval for generic eszopiclone containing between 0.3% and 1% of the l-isomer.  The FDA found this limit to be unacceptable and requested Dr. Reddy’s to reduce the l-isomer range to not more than 0.3%.  In response, Dr. Reddy’s revised its application to eszopiclone with 0% – 0.6% of the l-isomer.   At trial, Dr. Reddy’s moved for summary judgment of noninfringement, providing the judge with a certification that its eszopiclone products would contain only between 0.3% and 0.6% of the l-isomer.  The judge granted summary judgment, stating that Dr. Reddy’s eszopiclone products would be outside of the infringing range of less than 0.25%.

The Federal Circuit agreed with Sunovion and overturned the noninfringement decision on summary judgment.  In its opinion, the Federal Circuit panel pointed out that, unlike traditional infringement where an infringing product is made, used or sold, under the Hatch-Waxman framework the infringing action is the filing of the ANDA itself.  Consequently, the determination of infringement in such cases is made on the product for which approval has been requested from the FDA.  Any promise made by Dr. Reddy’s to stay outside the scope of the claims did not change the fact that it hoped to gain approval from the FDA to market a product that was covered by the claims.  The Federal Circuit reasoned that a finding of infringement was mandated, since the requested approval was for an aszopliclone product having an l-isomer content in the range of 0% – 0.6%, and that this range overlapped with the claimed range of less than 0.25%.  The panel summarized their position thus: “any so-called certification pledging not to infringe cannot override the conclusion that when a drug manufacturer seeks FDA approval to market a generic compound within the scope of a valid patent, it is infringement as a matter of law.”  The panel did note, however, that there may be some cases where the ANDA itself does not provide sufficient information to determine whether there is infringement and that it might be appropriate to use experimental test results under those exceptional circumstances.

The important takeaway from this is that an infringement inquiry looks first to the product described in the ANDA.  If that description provides the answer to infringement, the court will look no further and will consider no extrinsic evidence.  This case highlights the importance of ensuring that the description of the proposed generic product in an ANDA is outside the scope of the orange book patent claims if the manufacturer wants to mount a non-infringement defense.