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Court “Nixes” Patentee’s Mixes

February 13, 2001

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Last Month at the Federal Circuit - March 2001

Judges: Gajarsa (author), Newman, and Clevenger

In Biovail Corporation International v. Andrx Pharmaceuticals, Inc., No. 00-1260 (Fed. Cir. Feb. 13, 2001), the Federal Circuit affirmed a district court’s finding of noninfringement in favor of Andrx Pharmaceuticals, Inc. (“Andrx”).

Biovail Corporation International and Biovail Laboratories, Inc. (“Biovail”) are the exclusive licensees of U.S. Patent No. 5,529,791 (“the ‘791 patent”) directed to a drug to be taken once a day that is prescribed to treat hypertension and angina. Biovail markets the drug described in the ‘791 patent under the trade name Tiazac®.

In 1998, Andrx filed an Abbreviated New Drug Application (“ANDA”) with the United States Food and Drug Administration (“FDA”) for a generic version of Tiazac®. Andrx also filed a certification pursuant to paragraph IV of 21 U.S.C. § 355(j)(2)(A)(vii), asserting that its ANDA product does not infringe the ‘791 patent and that the ’791 patent is invalid. The Andrx product comprised a diltiazem salt (the active ingredient in Tiazac®) and sugar as a wetting agent.

Biovail filed suit against Andrx in the U.S. District Court in the Southern District of Florida, alleging infringement of the ‘791 patent under 35 U.S.C. § 271(e)(2)(A). The district court denied cross motions for SJ and subsequently held a bench trial, conducting both claim construction and infringement analyses. 

The district court had construed the claim term “admixture” to describe “two or more items [that] are commingled and interdispersed together to obtain a homogeneous product,” and ruled that claim 1 was limited to admixtures of the active ingredient diltiazem with a wetting agent. The district court had found that because the Andrx product was not mixed during the manufacturing process, it did not literally infringe claim 1. It further concluded that Biovail had failed to prove that an “admixture” forms in vivo following ingestion of Andrx’s product, as claimed. Finally, the district court found that Biovail was estopped from asserting that the Andrx product infringed claim 1 under the DOE because Biovail had amended the claim to add the “admixture” limitation during prosecution.

In affirming the district court’s finding of noninfringement, the Federal Circuit noted that the case turns on whether the admixture limitation must be “homogeneous.” Following a review of the prosecution history of the ‘791 patent, the Court determined that claim 1 was indeed limited to homogeneous mixtures of diltiazem with a wetting agent, based on arguments made by Biovail during prosecution to distinguish a prior art reference. The Federal Circuit then reviewed the district court’s findings that ingestion of the Andrx product does not result in a homogeneous admixture in vivo and concluded that these findings were not clearly erroneous.

Finally, relying on Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 234 F.2d 558 (Fed. Cir. 2000) (en banc), the Court determined that Biovail was completely barred from any range of equivalents for the “admixture” limitation because it had been added to claim 1 during prosecution for patentability reasons.

Accordingly, the Court affirmed the judgment of noninfringement.