Buprenorphine & Naloxone - USA

On Jul 12, 2019, Federal Circuit affirmed non-infringement & validity decisions of district court in Suboxone® case.  

Litigated patents in this case were U.S. Patents 8,603,514; 8,900,497; 8,017,150 and 8,475,832. Broadly these patents relate to pharmaceutical films with a uniform distribution of active ingredient with their components & process parameters.  Several generic drug companies (Dr Reddy’s Lab, Teva/Actavis, Alvogen) filed ANDAs to market generic versions of Suboxone® film prior to the expiration of the patents in suit. After trial, district court found DRL & Alvogen non-infringing & Actavis infringing. District court also upheld the validity of patents except US 8,475,832. Appeals & cross appeals filed.

Appeals involve issues of infringement and invalidity of these patents. Central issue litigated here was mainly based on “drying limitation” in the asserted claims. District court construed the claims to exclude “conventional top air drying” because specification disclaimed the conventional top drying as it produces non-uniform films. Inventors thus instead used bottom drying to dry the film so that there is uniform distribution of active ingredients. Federal Circuit affirmed the district court & held that Dr. Reddy’s & Alvogen’s manufacturing processes include conventional top drying & therefore do not infringe the asserted claims. Though some drying may happen at bottom of the film but this is very insubstantial.  Indivior argued that the specification describes other factors that affect film uniformity. But the court said that unequivocal disparagement of conventional top air drying demonstrates that other factors may not substitute for controlled drying of a wet cast film to achieve uniformity.

With respect to invalidation, Federal Circuit affirmed district court that the claims are not invalid for “indefiniteness” & are not obvious. The parties’ indefiniteness dispute focused on claim 62’s recitation of a “cast film comprising a flowable water-soluble or water swellable filmforming matrix.” Defendants argued that this limitation is indefinite because a cast film in its final dosage form is not flowable, and the claim thus required a physical impossibility. While the court agreed that the final cast film could not be flowable, it reasoned that a product claim may recite elements “in the state in which they exist during manufacture, before the final product exists.” And because the intrinsic evidence made clear that the cast film was made from a matrix that was flowable only before drying, the court concluded that the defendants failed to prove that the claims were indefinite.

With respect to obviousness, the key dispute between the parties was whether the prior art’s teachings would motivate a skilled artisan to make a uniform pharmaceutical film according to the claimed invention with a reasonable expectation of success. Federal Circuit affirmed district court& said that there was limited use of air convection dryers in the context of pharmaceutical films at the time of invention. Given the nascent status of pharmaceutical films at the time of invention and the limited knowledge of drying techniques, a person of ordinary skill would not have been motivated to combine the prior art to achieve uniformity. Secondary considerations also supported nonobviousness. The court considered evidence that obtaining pharmaceutical film content uniformity was a long-felt need yet difficult to achieve, and the court gave some credit to Inventor’s’s work related to the ’514 patent in solving that need. Federal Circuit thus agreed with Indivior & district court that claims are not invalid.