Endo Pharmaceuticals Solutions, Inc. v. Custopharm Inc., No. 2017-1719 (Fed. Cir. July 13, 2018)

The patents claim testosterone injections in a formulation consisting of castor oil and benzyl benzoate. The Abbreviated New Drug Application (ANDA) filer argued that the formulation was inherently disclosed in prior art articles describing clinical trials and pharmacokinetic properties of the drug in castor oil. The articles did not disclose the use of a co-solvent generally or benzyl benzoate specifically, but later disclosures indicated that the clinical trials described in the articles used the claimed formulation of castor oil and benzyl benzoate. The district court found that the prior art articles did not inherently disclose the formulation, the ANDA filer appealed, and the Federal Circuit affirmed. 

The doctrine of inherency requires that “the limitation at issue must be necessarily present, or is the natural result of the combination of elements explicitly disclosed by the prior art.” Although the clinical trials described in the articles had used the same formulation as claimed in the patents, the articles did not disclose the formulation until well after the priority date of the claims at issue. “The prior art was replete with potential co-solvents,” and there may have been other formulations that could achieve the same clinical and pharmacokinetic results. The ANDA filer had failed to present clear and convincing evidence that the claimed formulation was the only viable formulation and was therefore “necessarily present” in the prior art articles. Thus, the claimed formulation was not inherently disclosed.

A copy of the opinion can be found here