Reversing the district court’s erroneous claim construction, the U.S. Court of Appeals for the Federal Circuit held that Apotex’s product infringed SmithKline Beecham’s (now GlaxoSmithKline’s) claim covering the active ingredient of the antidepressant Paxil, but further held the claim invalid because SmithKline’s clinical tests prior to one year before filing constituted a public use not qualifying under the experimental use exception. SmithKline Beecham Corp. v. Apotex Corp., Case Nos. 03-1285, -1313 (Fed. Cir. Apr. 23, 2004) (Rader, J.) (Gajarsa, J., dissenting) (errata, Apr. 28, 2004).

Claim 1 of SmithKline’s U.S. Pat. No. 4,721,723, recites, in its entirety, "Crystalline paroxetine hydrochloride hemihydrate" (PHC hemihydrate), which is the active ingredient of SmithKline’s antidepressant drug Paxil. Apotex filed an Abbreviated New Drug Application (ANDA) with the U.S. Food and Drug Administration (FDA), seeking approval to market its own PHC antidepressant drug. Apotex identified the active ingredient in its antidepressant as PHC anhydrate and included in its ANDA a paragraph IV certification that its drug would not infringe the `723 patent. PHC anhydrate comprises crystals of PHC without bound water molecules. PHC hemihydrate comprises PHC crystals with one bound water molecule for every two PHC molecules.

Commencing its review with the claim construction, the Federal Circuit held that the district court erred in adding a "commercially significant" limitation into the compound claim by holding that anything less than a commercially significant quantity of the PHC hemihydrate falls outside the scope of SmithKline’s claim. Rather, the Court noted that the claim language unambiguously "describes a very specific compound without further limitation." The district court considered, but precluded such a broad, literal interpretation on the basis that it would produce an "absurd result." The Court, however, was emphatic that claim construction is not a policy-driven inquiry.

The Court also addressed the district court’s perceived conflict between claim breadth and indefiniteness under §112, noting that the claim covers a definite chemical structure and, regardless of its breadth, cannot be indefinite under §112. Addressing its 1993 decision in Morton Int’l v. Cardinal Chem., the Court noted that a claim to a chemical compound is only indefinite if "one skilled in the art could not determine whether a given compound was within the scope of the claim" and "does not depend on a potential infringer’s ability to ascertain the nature of its own accused product to determine infringement."

Turning to the issue of experimental use, the Federal Circuit emphasized its commitment to the strict requirements of the experimental use negation of the statutory bar as being limited to testing claimed features, or features "inherent" in a claimed composition. Here, the Court pointed out that the claim at issue broadly covered PHC hemihydrate regardless of use and concluded that SmithKline’s clinical trials to establish the efficacy and safety of the compound as an antidepressant for FDA approval did not involve the claimed features of the invention so as to qualify as experimental use.

In a concurrence that featured a sua sponte analysis of §101, Judge Gajarsa concluded that, because the manufacture of PHC hemihydrate could be "a natural physical process" occurring "under normal climactic conditions and with no human intervention," the claim at issue was invalid as directed to an unpatentable process of nature.

Practice Note: This case is a reminder to patentees that testing the properties, uses and commercial significance of a compound claimed solely in structural terms may start the clock under §102(b) for any claim that is not limited by any property, commercially significant amount or other use of the compound.

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