Federal Circuit Affirms Invalidity of OxyContin® Patents[1]: The Low ABUK Patents

Yesterday, the Federal Circuit affirmed a decision from the Southern District of New York that four patents listed in the Orange Book for OxyContin® are invalid as anticipated and obvious in Purdue Pharma, L.P. v. Teva Pharmaceuticals USA, Inc.  This decision addressed two groups of patents:  three product-by-process patents directed to oxycodone API, and a fourth patent directed to tamper resistant formulations of opioids.  Today we will address the portion of the decision concerning the product-by-process patents.

The Low ABUK Patents. Three of the four patents were directed to oxycodone with low levels of impurities known as “ABUKs” (alpha, beta unsaturated ketones) thought to be toxic at high levels. As Purdue explains it, the inventors discovered that these impurities were created by a compound—8-α—that was unwittingly formed during one of the earlier synthetic steps. Purdue argued that the discovery of 8-alpha was a nonobvious discovery that paved the way for the synthetic solution to the ABUK problem.  To highlight the relevance of this discovery, the inventors drafted their claims in product-by-process form, to cover oxycodone API with low-ABUK levels.  The claims further specified that the ABUK was “derived from” 8- α, as opposed to another known source of ABUK called 8-β.

The Federal Circuit Decision. In affirming the district court’s obviousness ruling, the Federal Circuit concluded that the source of the ABUK present in the end product, be it 8-α or 8-β, was immaterial to the analysis. Purdue chose to claim the end product—low ABUK oxycodone­—not the solution to the problem­—a specific synthetic process.  Second, ABUK is ABUK no matter its source.  That is, the claim limitation referring to the source of the ABUK was only a process parameter that did not impart any structural or functional differences to the claimed product.  For this reason, the Federal Circuit held the court was correct to disregard this limitation when it performed its obviousness analysis.  Third, there were known methods for removing ABUK that could be used regardless of how that ABUK came to be present in the oxycodone.

The Federal Circuit also affirmed the lower court’s decision to discount secondary considerations.  The Court held that Purdue failed to show a nexus between the invention and the alleged commercial success because the inventor failed to market its low-ABUK oxycodone API to anyone but its corporate affiliate (Purdue) who purchased its oxycodone from Rhodes because it was cheaper.  The Court also held that there was no long-felt need.  While there was awareness that ABUKs may present toxicity concerns, there was no pressing need for companies to create low-ABUK product until the FDA issued a mandate.  And no companies failed to meet that mandate.

The Takeaway:  Process parameters set forth in product-by-process claims may be disregarded when assessing obviousness if they do not impart any structural or functional properties to the claimed product.