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Patents Covering Duragesic® Transdermal Fentanyl Patch Upheld

December 10, 2004

Decision icon Decision

Last Month at the Federal Circuit - January 2005

Judges: Archer (author), Newman, and Dyk (concurring-in-part and dissenting-in-part)

In Alza Corp. v. Mylan Laboratories, Inc., No. 04-1344 (Fed. Cir. Dec. 10, 2004), the Federal Circuit affirmed a finding that U.S. Patent No. 4,588,580 (“the ‘580 patent”) is not invalid and had not been procured by inequitable conduct.

Alza Corporation and Janssen Pharmaceutica, Inc. (collectively “Alza”) asserted the ‘580 patent against Mylan Laboratories, Inc. and Mylan Pharmaceuticals, Inc. (collectively “Mylan”). The ‘580 patent concerns a system for the transdermal administration of the narcotic fentanyl for an extended period of time at analgetically effective rates. In particular, the ‘580 patent is directed to the transdermal administration of fentanyl in its base form. One embodiment of the ‘580 patent is sold by Janssen as the Duragesic® patch. Mylan developed a generic transdermal fentanyl patch that is a bioequivalent to Duragesic® and filed an ANDA seeking approval to market its patch before the ‘580 patent expires. The ‘580 patent has been through two reexamination proceedings.

The claims in question all recite the claim limitation “skin permeable form.” The district court construed this to mean fentanyl that is in a form that can pass through the skin, excluding solutions of fentanyl citrate. Based on this construction, the district court concluded that Mylan’s application for an ANDA was an act of infringement. The district court also concluded that one prior art reference (“the Keith reference”) did not anticipate because it disclosed fentanyl citrate, which had been expressly disclaimed by the inventors in the ‘580 patent specification and during the patent’s prosecution. The Federal Circuit agreed that the patent specification clearly demonstrated that fentanyl citrate is not a skin-permeable form of fentanyl and that this was confirmed by the prosecution history. The Court agreed that because the Keith reference teaches a fentanyl citrate solution that was expressly disclaimed by the ‘580 patent’s inventors, the Keith reference did not anticipate. Concerning obviousness, other prior art that Mylan wanted to combine with the Keith reference actually taught that fentanyl would not be a good transdermal candidate due to its low solubility.

Mylan had also argued that the ‘580 patent was unenforceable for inequitable conduct, specifically, for misleading statements submitted in a declaration filed by one of the inventors during one of the reexamination proceedings. The Federal Circuit found, however, that the statements made in the declaration were true, no information had been omitted, and no information was affirmatively misstated. Moreover, the district court had the opportunity to question the declarant in determining the witness’s credibility. Accordingly, the Federal Circuit agreed that inequitable conduct had not been shown.

Judge Dyk agreed with the findings on validity, but would have found inequitable conduct. He was troubled by the majority’s conclusions that the statements in the declaration had not been shown to be untrue. According to Judge Dyk, there was no basis to find certain statements in the declaration literally true. Accordingly, he considered a remand necessary to reconsider the issue of intent.