By Dennis Crouch
In an important Hatch-Waxman related decision, the Federal Circuit has affirmed the lower court’s holding that Purdue Pharma’s abuse deterrent OxyContin patent claims are invalid as anticipated and/or obvious over the prior art.
Of interest, it appears that the patentee was harmed here by the Patent Act’s objective approach to obviousness that, according to the statute, must be considered without regard to the actual “manner in which the invention was made.” In particular, during the process of creating its low-ABUK oxycodone, the innovators first discovered an 8α impurity isomer created during drug manufacture that led to a problematic 14-hydroxy compound. The claimed invention was a product having a reduced 14-hydroxy level. In the appeal, the Federal Circuit noted that, while the 8α impurity may have been a new discovery, it was not necessary to achieve the claimed low-ABUK results. In particular, the court noted that reduction of both the 8α and 8β impurities would also achieve the same result without having to distinguish between the two — affirming that “a skilled artisan would recognize that hydrogenation could be used to remove the remaining 14-hydroxy, regardless of the source of the 14-hydroxy.”
Of course, the claims did expressly require that the impurity being reduced be “derived from 8α.” That limitation, however, was deemed an illusory product-by-process limitation.
We also conclude that, because “derived from 8α” is a process limitation, the district court did not err in disregarding the limitation in its obviousness analysis. We have clearly stated that “‘[i]n determining validity of a product-by-process claim, the focus is on the product and not the process of making it.’” Greenliant Sys., Inc. v. Xicor LLC, 692 F.3d 1261 (Fed. Cir. 2012) (quoting Amgen Inc. v. F. Hoffman-La Roche Ltd., 580 F.3d 1340 (Fed. Cir. 2009)). “That is because of the . . . longstanding rule that an old product is not patentable even if it is made by a new process.” Id.; see also SmithKline Beecham Corp. v. Apotex Corp., 439 F.3d 1312, 1317 (Fed. Cir. 2006) (“It has long been established that one cannot avoid anticipation by an earlier product disclosure by claiming . . . the product as produced by a particular process.”); In re Thorpe, 777 F.2d 695, 697 (Fed. Cir. 1985) (“If the product in a product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process.”).
In Amgen, the Federal Circuit did find that the particular claimed process will be relevant if it imparts distinguishing structural differences on the resulting product. Here, however, the court found that the fact that the negative 14-hydroxy byproduct was derived from 8α “imparts no structural or functional differences” over the prior art that already included low-ABUK product achieved without focusing on the 8α isomer.
Generic OxyContin has been on the market for the past year – following the district court judgment that has now been affirmed – and so this decision should not have a major market impact.
This case here is one part of a complex web of battles that Purdue appears to be fighting to protect its exclusive rights to sell OxyContin – or at least delay competition. Although these asserted claims have been found invalid, Purdue is asserting a set of new patents, including U.S. Patent Nos. 8,309,060, 8,337,888, 8,808,741, 8,894,987, 8,894,988, 9,060,976, 9,034,376 and 9,073,933.
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 App. No. 2014-1294 (Fed. Cir. 2016); on appeal from In re OxyContin Antitrust Litig., 994 F. Supp. 2d 367 (S.D.N.Y. 2014).
 Asserted patents include U.S. Patent No. 7,674,799 (“’799 patent”), U.S. Patent No. 7,674,800 (“’800 patent”), U.S. Patent No. 7,683,072 (“’072 patent”) (collectively, “the low-ABUK patents”), and U.S. Patent No. 8,114,383 patent (“’383 patent”).