Federal Circuit Affirmed District Court Decision That Patent Satisfied Written Description Requirement Without The Method Disclosed In The Specification

  • November 1, 2019


Nalpropion Pharmaceuticals, Inc. v. Actavis Laboratories FL, Inc., No. 2018-1221

In Nalpropion, the Federal Circuit affirmed a district court decision that Actavis’s patent satisfied the written description requirement even though the patent’s required dissolution profiles were obtained using a method not disclosed in the specification, because that claim language was “substantially equivalent” to the method for obtaining dissolution profiles that was disclosed in the specification.

Nalpropion markets Contrave®, an extended release tablet containing a fixed amount of both naltrexone and bupropion for the treatment of obesity. Actavis filed an Abbreviated New Drug Application to enter the market with a generic form of Contrave®, which resulted in Nalpropion asserting three patents against it. Actavis counterclaimed that one of the patents lacked written description support because the claim in question required that the dissolution profile of the tablet be characterized using a specific method (USP 2 Method), even though the specification disclosed dissolution profile data obtained using a different method (USP 1 Method). The district court held that the specific method used was not relevant to whether the inventors has possession of the invention, and further asserted that claimed method and the method used to obtain the dissolution data in the specification were “substantially equivalent.” As such, the court held that the claim was adequately supported, ruling in favor of Nalproprion.

The written description of an invention must clearly allow persons of ordinary skill in the art to recognize that the inventor invented what is claimed. The test for sufficiency is whether the disclosure of the application relied upon reasonably conveys to those skilled in the art that the inventor had possession of the claimed subject matter as of the filing date.

The Federal Circuit held that the district court’s factual determination that the USP 1 and USP 2 methods were substantially equivalent was supported by substantial evidence, and affirmed on that basis. Although it is normally the case that the written description requirement cannot be satisfied by a so-called equivalent disclosure, the Federal Circuit concluded that in this case, the district court’s fact finding, combined with the fact that the equivalence related to the resulting dissolution profile and not to the operative claim steps of treating obesity using naltrexone and bupropion, the written description requirement could be satisfied by such an equivalent disclosure. Judge Lourie, writing for the majority, argued that “[r]igidity should yield to flexible, sensible interpretation.

Key takeaway: Generally, the written description requirement may not be satisfied by a disclosure that is allegedly equivalent but that fails to show that the patentees possessed what was claimed. However, where the disputed claim limitation relates only to a resultant parameter, and not the operative steps of the claimed method, and where there is strong factual support for the alleged equivalence of the claimed method and the method of the disclosure, the written description requirement may be satisfied under a “flexible, sensible interpretation” of the requirement.


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