Federal Circuit Affirms Invalidity of OxyContin® Patents : The Tamper-Resistance Patent
On Monday, 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 post addresses the second half of that decision, which was directed to a patent covering tamper resistant opioid formulations. While the case was focused on Purdue’s OxyContin® product, this tamper-resistance patent (U.S. Patent No. 8,114,383) is listed in the Orange Book for other opioid products, such as Opana ER®.
The Tamper-Resistance Patent. The tamper-resistance patent was owned by Grunenthal and licensed to a number of drug manufacturers, including Purdue. The claims were directed to formulations that make it more difficult for abusers to crush and snort or inject opioid dosage forms, such as oxycodone, to elicit a “high” similar to that of heroine. Grunenthal’s patent required the formulations to have high “breaking strengths” in order to deter tampering.
The Federal Circuit affirmed the court’s judgment of anticipation, based on a reference known as “McGinity.” McGinity described the use of hot-melt extrusion of high molecular weight PEO to create controlled-release dosage forms. Among the claim limitations at issue was whether McGinity disclosed oxycodone. McGinity identified the formulations as being suitable for use with compounds from a variety of therapeutic classes, including “analgesics” “such as aspirin, acetaminophen, diflunisal and the like.” Purdue argued that identified compounds were all non-opioids and so this category should be confined to non-opioid analgesics. The Federal Circuit disagreed, holding that the “such as” and “and the like” language referred to a broader group of analgesics than those expressly identified. Further, the Court credited the district court’s findings that opioids were a major class of analgesics, and that McGinity was concerned with sustained-release dosage forms and oxycodone was one of the few sustained release analgesics on the market at the time.
Purdue also disputed that Teva had adequately demonstrated that McGinity taught formulations having the requisite breaking strength. The Federal Circuit rejected this argument as well. While McGinity did not discuss the breaking strength of the tablets, Teva’s expert, Dr. Fernando Muzzio, offered “experimental results [that] indicate[d] unanimously, reliably, clearly, and convincingly that any tablet made according to the McGinity Application would exhibit this characteristic.” The court found this experimental evidence “pivotal” to Teva’s inherency defense.
The Takeaway. Invalidity defenses based on inherency will often require carefully designed experiments that correspond to the scope of the passages from the prior art reference upon which the defense is based. But with this evidence, courts may find anticipation based on a prior art reference that does not otherwise address a critical claim element.
 Carlson Caspers had the pleasure of representing Teva at both the trial court and on appeal at the Federal Circuit.