Oxycodone - USA

On Apr 17, 2019 Federal Circuit affirmed PTAB’s decision that claims of oxycodone formulation patent with gelling agent are obvious over certain prior arts.

Purdue appealed from the decisions of the PTAB in IPRs, IPR2016-01412 and IPR2016-01413. The Board found claims 1–13 and 16–19 of U.S. Patent No. 9,034,376 unpatentable as obvious. The ’376 patent, entitled “Pharmaceutical Formulation Containing Gelling Agent,” is directed to abuse-deterrent, extended release formulations of oxycodone. The ’376 patent contemplates using two gelling agents, polyethylene oxide (“PEO”) and hydroxypropylmethylcellulose (“HPMC”) in an oxycodone formulation. When the oxycodone formulation is exposed to an aqueous liquid, those gelling agents impart a viscosity to the formulation that makes it unsuitable for parenteral and nasal administration.

Prior to reaching the merits in both proceedings, the Board addressed Joshi’s status as prior art. Amneal (Petitioner) contended that Purdue was collaterally estopped from relitigating Joshi’s availability as prior art based on the final judgment in a district court case regarding U.S. Patent No. 8,337,888, which derived from the same provisional application as the ’376 patent. The Board held that Purdue was collaterally estopped from challenging Joshi’s status as prior art. The Board recognized that Purdue has never previously argued that Joshi (filed on Aug 30, 2001 which claims priority to Apr 30, 2001) did not qualify as prior art. The Board further held that, even if collateral estoppel did not apply to the issue of Joshi’s priority, Joshi qualifies as prior art under section 102(e) because Purdue failed to satisfy its burden of production to show that the ’376 patent is entitled to a filing date earlier than August 6, 2002. Because the claims of the ’376 patent do not have written description support in either the ’534 provisional or a draft of the patent application dated April 25, 2001.

On appeal, Purdue challenged the Board’s conclusion that Joshi qualifies as prior art. Purdue contended that the Board improperly invoked collateral estoppel, and that the claims of the ’376 patent do not have written description support in the ’534 provisional application. Purdue also challenged the Board’s conclusion that claims 1–13 and 16–19 of the ’376 patent are unpatentable as obvious. It argued that a person of ordinary skill would have lacked motivation to combine HPMC and PEO in an abuse-deterrent, extended release oxycodone formulation, and would have lacked a reasonable expectation of success in doing so.

Purdue challenged the Board’s invocation of collateral estoppel on two grounds: that the issue of Joshi’s priority was not actually litigated in the district court case involving the ’888 patent, and that the priority issues regarding the ’888 patent are not identical to the priority issues for the ’376 patent. Federal Circuit agreed with Purdue & held that Joshi’s priority was not actually litigated in the district court case involving the ’888 patent, and therefore do not address whether the priority issues regarding the ’888 patent are identical to the priority issues for the ’376 patent. Federal Circuit further said that Board's collateral estoppel ruling on the notion that “collateral estoppel applies to ‘issues that were or could have been raised’ in the prior litigation, however conflates the principles of collateral estoppel and res judicata. Federal Circuit further said that there is no support for the proposition that failing to distinguish between a provisional and non-provisional application, without more, indicates that Joshi’s priority date was actually litigated. Nor does the fact that Joshi’s priority date might have been a potentially important question in the earlier litigation mean that it was actually litigated. The priority date for the Joshi reference therefore cannot be determined based on collateral estoppel.

With respect to the priority to ’534 application, Federal Circuit said that in the ’534 application disclosure, PEO and HPMC are merely two of many undifferentiated compounds that fall within the genus of gelling agents. Such “laundry list” disclosures do not provide adequate specificity to constitute written description support for Purdue’s claim of priority. To be sure, the language “mixtures thereof” suggests the possibility of combining two or more of the listed gelling agents. Without more, however, that language fails to highlight any preference for how many and which gelling agents to combine. Federal Circuit held that the additional references to PEO and HPMC throughout the provisional application do not constitute “blaze marks” that indicate or direct that a particular combination should be made “rather than any of the many others which could also be made. Accordingly, the court found that substantial evidence supports the Board’s conclusion that the claims of the ’376 patent do not have written description support in the ’534 provisional application. Therefore, Joshi qualifies as prior art under 35 USC 102(e).

With respect to the obviousness, Federal Circuit found Purdue’s each argument unconvincing. Federal Circuit sided with PTAB which held that prior arts teach the claimed invention. Specifically, Royce teaches a sustained release formulation that includes both PEO and HPMC. Royce also suggests that sustained release dosage formulations may be used for analgesics, a category of drug that includes oxycodone. McGinity teaches controlled release dosage forms of analgesics. Hoffmeister and Joshi teach that HPMC and PEO are gelling agents that may be used in an abuse-deterrent formulation. And the PDR teaches extended release oxycodone formulations in doses of 10 mg, 20 mg, 40 mg, and 80 mg. Person skilled in the art thus would have been motivated to use HPMC & PEO with reasonable expectation of success.

Federal Circuit therefore affirmed the Board’s determination that claims 1–13 and 16–19 of the ’376 patent are unpatentable for obviousness.