Client Alert
Differences in an Inactive Ingredient That Do Not Change How the Claimed Invention Works Are Not “Substantial” Under the Doctrine of Equivalents
Client Alert
Differences in an Inactive Ingredient That Do Not Change How the Claimed Invention Works Are Not “Substantial” Under the Doctrine of Equivalents
June 24, 2019
UCB, Inc. v. Watson Laboratories Inc., Nos. 2018-1397, 2018-1453 (Fed. Cir. June 24, 2019)
The patentee brought suit alleging patent infringement by a proposed generic version of the drug Neupro (transdermal rotigotine). The district court concluded that under the doctrine of equivalents, an inactive ingredient (polyisobutylene adhesive) used in the accused generic product was equivalent to a “matrix . . . based on []an acrylate-based or silicone-based polymer adhesive system.” Specifically, the district court found that under the insubstantial differences test, a skilled artisan would understand that polyisobutylene shares several properties with acrylates and silicates relevant to forming a polymer adhesive system. While polyisobutylene differs from the claimed acrylates and silicates in numerous respects — including chemical structure and polarity — the district court found that these differences did “not change how the polymer adhesive system works,” and therefore did not preclude a finding of equivalency.
The Federal Circuit affirmed, explaining that the district court reasonably explained that a skilled artisan would find polyisobutylene equivalent to an acrylate-based or silicone-based polymer adhesive, and “why the similarities matter more than the differences for the claimed system.” The Federal Circuit also rejected arguments that the patentee was legally barred from asserting equivalency, explaining, for example, that the patentee did not surrender polyisobutylene as an equivalent where it was unrelated to the examiner’s restriction requirement.