Addressing obviousness in the context of a non-obvious problem source, the US Court of Appeals for the Federal Circuit affirmed the US District Court for the Southern District of New York's ruling that the claimed product was obvious where one would have arrived at the claimed product without knowing the source of the problem. Purdue Pharma L.P. v. Epic Pharma, LLC., 811 F.3d 1345 (Fed. Cir., Feb. 1, 2016) (Prost, C.J.)

The case concerned an improved version of the opiate pain reliever OxyContin® (oxycodone HCI) that no longer contained an excessive amount of a toxic byproduct, 14-hydroxy. The excess 14-hydroxy was thought to be derived from two sources: 8α and 8β. While 8β was known in the art to be a source of 14-hydroxy, Purdue scientists were the first to discover 8α as a source. They found that 8α, formed early in the manufacturing process, was being converted to 14-hydroxy during the step of converting the oxycodone free base to oxycodone hydrochloride (the API)—the salting step. The scientists also determined that adding a hydrogenation step after the salting step fixed the problem of excess 14-hydroxy. The claims at issue cover the API with low levels of the toxic 14-hydroxy, but explicitly recite 8α as the source of at least a portion of 14-hydroxy remaining after the salting step.

On appeal, Purdue argued that the lower court failed to properly credit the core of its claimed inventions, i.e. its discovery of 8α. According to Purdue, because the source of the problem was non-obvious, the solution also is non-obvious as a matter of law, and that without knowing that 14-hydroxy is derived from 8α, a skilled artisan would not know when and under what conditions to perform the hydrogenation step. The Federal Circuit rejected Purdue's arguments. It distinguished legal precedent, explaining that Purdue is not claiming the remedy to the problem of excess 14-hydroxy after the salting step, i.e., performing the second hydrogenation step, but instead is claiming the end-product which may be arrived at even if the source of the problem was unknown. Expanding further on the breadth of the patent claims at issue, the court noted that if the patent claims had required the remedy of hydrogenating the salt, Defendants' product would not infringe. Likewise, the court noted that the conditions for removing 14-hydroxy derived from 8β would not be any different from that for removing 14-hydroxy derived from 8α, rejecting Purdue's argument that one would not know the conditions necessary for the hydrogenation step without knowing that 14-hydroxy is derived from 8α.

Purdue also contended that the claim limitation "derived from 8α[ ]" was improperly identified as a process limitation and incorrectly disregarded. Rejecting Purdue's arguments, the court explained that "derived from 8α[ ]" is a process limitation: it does not describe the structure of 14-hydroxy, impart any new structure on 14-hydroxy or require a different hydrogenation process for removal. As to the relevance of a process limitation in obviousness analysis, the court noted that the focus remains on the product, not the process by which it is made in a product-by-process claim because of the "longstanding rule that an old product is not patentable even if it is made by a new process." The court also declined to find this case to be an exception because the claim limitation did not impart any new "structural or functional differences" distinguishing the claimed product from prior art. According to the court, no new structure is imparted on 14-hydroxy nor is the hydrogenation process different because 14-hydroxy is derived from 8α.

Practice Note

Do not assume that a solution to a problem would be non-obvious because a source of the problem was non-obvious—how the invention is claimed matters. Beware of drafting the novel aspect of the invention as a process limitation in a product claim.

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