Aventis Pharma., Inc. v. Amino Chemicals Ltd.

Reversing and remanding the case finding that the district court misconstrued the term "substantially pure."

July 15, 2013

GENERICally Speaking: A Hatch Waxman Litigation Bulletin

Case Name: Aventis Pharma., Inc. v. Amino Chemicals Ltd., Fed. Cir. No. 2011-1335, 2011-1336, 2013 U.S. App. LEXIS 10007 (Fed. Cir. May 20, 2013) (Circuit Judges Newman, Bryson and Reyna presiding; Opinion by Reyna; Dissent by Bryson) (Appeal from D.N.J., Brown, C.J.)

Drug Product and Patent(s)-in-Suit: Allegra® (fexofenadine); U.S. Pat. No. 5,750,703 (“the ’703 patent”)

Nature of the Case and Issue(s) Presented:  The parties stipulated to non-infringement following the district court’s Markman opinion. The case concerns the processes used to make various piperidine derivatives, which are commonly used as active ingredients in antihistamines. The term “substantially pure” appears in claim 1 of the ’703 patent in two claim limitations—(i) “providing a substantially pure regioisomer of the following formula…;” and (ii) “converting the substantially pure regioisomer to the piperidine derivative compound….” The district court construed the terms “substantially pure regioisomer of the following formula” and “substantially pure” as requiring 98% purity of both the intermediate and final products. The district court found that the specification indiscriminately equates the purity of the intermediates and the final product. The district court found that the prosecution history of the ’703 patent and the prosecution history of a related divisional patent, U.S. Pat. No. 5,578,610 (“the ’610 patent”) demonstrated that the inventor clearly and unambiguously disavowed any other claim scope. The Federal Circuit reversed, finding that a single construction for the term “substantially pure” with respect to both the intermediate and final product was incorrect and adopting a different claim construction.

Why Aventis Prevailed:  The Federal Circuit found that it was improper to rely on the divisional ’610 patent when construing the term “substantially pure.” The court, and the parties agreed, that the claims themselves were insufficient to define “substantially pure.” The court noted that, while “substantially pure” refers both to the intermediates and the end product in the specification, the claims use “substantially pure” only in reference to the intermediate. The Federal Circuit also noted that one of ordinary skill in the art would recognize that an intermediate would not be required to have the same purity as the end product. Therefore, the court concluded that the “one-size-fits-all” construction for “substantially pure” truncates the claim term “substantially pure regiosiomer,” and that such a construction was wrong. The district court also erred in its actual construction of the term. The Federal Circuit found that the statements during the prosecution of the divisional patent were little help in construing the term. The district court assumed that “substantially pure” must apply to all impurities present in solution, not just regioisomeric purity. The Federal Circuit disagreed stating that one of ordinary skill in the art would understand that the ’703 patent improved the regioisomeric purity of the end product compared to the prior art. The Federal Circuit also found that the processes disclosed in the ’703 patent and the prior art required further purification. Rather than requiring a numerical boundary for purity, the Federal Circuit adopted Aventis’s proposed construction that “substantially pure regioisomer of the following formula” means “largely but not wholly the para regioisomer of the intermediate of the structure shown, as compared to the meta isomer.”

Judge Bryson dissented, and would have affirmed the district court’s finding that the term “substantially pure” should apply to both the intermediate and the end product. Judge Bryson disagreed with the majority’s construction since it ignored the intrinsic record and the presumption that the terms have a consistent meaning throughout the patent. According to Judge Bryson, if the patentee wanted “substantially pure” to have different meanings when it applied to different elements, it needed to explicitly “unlink” them.

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