Amneal Pharmaceuticals came up short in its bid to knock out numerous claims of Endo Pharmaceuticals’ US Patent No. 8,329,216 in a Final Written Decision issued on July 22, 2015, Amneal Pharm., LLC v. Endo Pharm. Inc., IPR2014-00360. The ‘216 patent relates to oral controlled release pharmaceutical formulations comprising oxymorphone and related methods for pain relief. A strong lesson learned in this case is that arguments based on inherency can be difficult and it is important to introduce sufficient evidence to demonstrate that a purported “inherent disclosure” necessarily is present in the prior art. Bare expert testimony is often insufficient.

At the outset of its analysis, the PTAB construed “controlled release” and “about” from the claims of the ‘216 patent. The Board adopted Petitioner’s proposed constructions: 1) controlled release = release no more than about 80% of their active pharmaceutical ingredients within 60 minutes (taken from specification); and 2) about = at least the standard statistical error.

Petitioner’s obviousness argument was largely based on the contention that the prior art inherently disclosed a dissolution profile that required “two or three peaks” of blood plasma levels of the active ingredient. The vast majority of the Board’s decision discussed whether Petitioner had sufficiently shown that the prior art necessarily disclosed the claimed dissolution profile. For example, with regard to one of the grounds for unpatentability, Patent Owner attacked this argument by citing to certain clinical studies, including one disclosed to the FDA, that showed that two or three peaks did not necessarily occur. Petitioner sought to rebut this argument by explaining that the data in that clinical study was not tested frequently enough to show multiple peaks, but there was insufficient evidence provided on this point.

The takeaway from this case is that an argument based on inherent disclosure can be fact intensive and requires strong evidence that the limitation necessarily is in the prior art. Often, an expert declaration is not sufficient – certainly not one that merely states conclusorily that the property is inherent. Testing, reference to studies, etc. is required to prove this type of argument.