In Persion Pharmaceuticals LLC v. Alvogen Malta Operations Ltd., No. 18-2361 (Fed. Cir. Dec. 27, 2019), the Federal Circuit affirmed a district court’s decision that Persion Pharmaceutical’s asserted claims were invalid as obvious under 35 U.S.C. § 103.

The two asserted patents in this case are Orange Book listed in connection with the drug product Zohydro ER. The patent claims in this case cover not only the specific Zohydro ER formulation but also methods of using any extended-release formulation with hydrocodone as the only active ingredient to treat pain in patients with compromised liver functionality.

In March 2016, Persion sued Alvogen after Alvogen filed an ANDA seeking approval for a generic version of Zohydro ER. After a bench trial, the district court concluded that the asserted claims in this case were invalid as obvious under § 103. Specifically, the district court found that a person of ordinary skill in the art would have been motivated to administer a particular prior art hydrocodone formulation to patients with compromised liver function. Furthermore, the court found that the pharmacokinetic limitations in this case were “inherent in any obviousness combination” because the recited parameters in these patents were “necessarily present” in the particular prior art references identified by Alvogen. The district court also found the asserted claims in this case invalid under § 112 for inadequate written description support.

On appeal, Persion contended that the district court improperly relied on inherency because no singular piece of prior art taught administering a hydrocodone-only formulation to patients with compromised liver functionality. The Court disagreed, explaining that in this case “inherency may supply a missing claim limitation in an obviousness analysis where the limitation at issue is the natural result of the combination of prior art elements.” Thus, the Court found that the district court in this case did not err in relying on inherency because the combination of these particular prior art elements necessarily resulted in a formulation in this case that exhibited the claimed pharmacokinetic parameters.

Persion further argued that the district court erred in relying on pharmacokinetic data from formulations and patient groups not covered by the asserted claims. The Court once again disagreed, explaining that the toxicity of the additional drugs in this case would have motivated a skilled artisan to develop a hydrocodone-only formulation that would be safer and less toxic than the combination formulations disclosed in the particular prior art cited by Alvogen.

The Federal Circuit rejected Persion’s remaining arguments and affirmed the district court’s finding that the asserted claims are invalid as obvious under 35 U.S.C. § 103. Having found that the asserted claims were all invalid for obviousness in this case, the Federal Circuit did not comment on the district court’s decision regarding lack of written description support.