Purdue Pharma L.P v. Accord Healthcare Inc.

Case Name: Purdue Pharma L.P v. Accord Healthcare Inc., Civ. No. 22-913-WCB, 2024 WL 4120717 (D. Del. Sept 9, 2024) (Bryson, J.)

Drug Product and Patent(s)-in-Suit: OxyContin® (oxycodone HCl); U.S. Patent No. 11,304,908 (“the ’908 Patent”)

Nature of the Case and Issue(s) Presented: Accord submitted an ANDA seeking to sell a generic version of Purdue’s OxyContin® product. Accord argued that Purdue was collaterally estopped from asserting the ’908 patent based on a prior judgment against Purdue on three related patents. The ’908 patent is directed to an extended-release pharmaceutical dosage form comprising a shaped, convention heated matrix with polyethylene oxide (“PEO”) and certain rheological characteristics. After trial and post-trial briefing, the court found the ’908 patent invalid as obvious.

Why Accord Prevailed: Accord argued that the ’908 patent was obvious because a POSA was motivated, with a reasonable expectation of success, to adapt a prior art reference, Bartholomäus, to generate a tamper-resistant matrix tablet on a commercial scale by using a convection heating device such as a coating pan and by heating the tablets without simultaneous exposure to pressure. Accord further argued that collateral estoppel resolved most, if not all, issues of the obviousness analysis in its favor.

With regard to collateral estoppel, the court explained that the prior district court decision was pending on appeal. And while collateral estoppel can be applied without a final Federal Circuit decision, the court nevertheless decided to address Accord’s obviousness argument on the merits.

Purdue made several arguments in support of the non-obviousness of the ’908 patent. The Court rejected each argument. First, Purdue argued that Bartholomäus was not a proper lead reference. In particular, Purdue argued that Bartholomäus was not a good starting point for an anti-abuse strategy, given that as of the effective filing date, the industry was more focused on other strategies, such as antagonists. The court disagreed with this conclusion and noted that nothing in the prior art criticized the approach taken by Bartholomäus, meaning that although there might have been other approaches to reducing abuse, a POSA still would have been motivated by the teachings of Bartholomäus. Second, Purdue argued that three claim limitations were missing from Bartholomäus and that a POSA would not have been motivated with a reasonable expectation of success to arrive at the claimed invention. As to the limitation requiring heated PEO particles that fuse with the matrix, the court found that Purdue was estopped, based on arguments made in a prior litigation, from arguing that this limitation was not taught by Bartholomäus. With regard to the heating by convection oven or in a coating pan, the court credited Accord’s expert testimony explaining that a coating pan is a common piece of equipment in a tablet manufacturing facility and that a POSA would be motivated to use this approach. As to the compression before heating and time of heating limitations, the court concluded that Purdue’s litigation positions were contrary to their description of the same prior art in a previous litigation and also credited the testimony of Accord’s expert. Third, Purdue advanced secondary indicia of non-obviousness. With regard to failure of others, Purdue identified the approval and subsequent withdrawal of another opioid, Endo’s Opana®. Given the different API and inactive ingredients in Opana®, the court was unpersuaded that the withdrawal of this drug product established failure of others. The court also rejected Purdue’s statements of industry skepticism, as FDA’s delay in approving Purdue’s drug product was not “skepticism.” Further, with regard to acclaim, Purdue presented testimony from only a named inventor, which the court did not credit as supporting any indicia of non-obviousness. Finally, the court rejected Purdue’s argument of unexpected results because the alleged unexpected property—reduced tablet density—was minimal and not material to the invention. The court concluded that no alleged secondary indicia of non-obviousness supported the alleged non-obviousness of the ’908 patent.