IMPAX LABORATORIES INC. v. LANNETT HOLDINGS INC.

Federal Circuit Summary

Before Lourie, Dyk, and Taranto. Appeal from the  District Court for the District of Delaware.

Summary:  A passing reference in the prior art to a formulation containing the claimed active ingredient and the claimed administration route may not be sufficient to invalidate a claim.

Astrazeneca AB, Astrazeneca UK Limited, and their exclusive licensee Impax Laboratories Inc. (together, “Astrazeneca”) sued Lannett Holdings Inc. (“Lannett”) for patent infringement based on Lannett’s ANDA seeking approval to manufacture and sell generic versions of Zomig® Nasal Spray.  The asserted claims addressed a zolmitriptan formulation capable of nasal administration.  Appellant argued the asserted claims were invalid as obvious over, inter alia, a reference disclosing an oromucosal formulation that indicates the formulation could also be administered intranasally and may use zolmitriptan as the active ingredient.  Despite this disclosure, the district court found after a bench trial that the prior art taught away from formulating zolmitriptan for intranasal administration because of the prior art’s teaching that the active metabolite of zolmitriptan was more effective than zolmitriptan itself, while a nasal spray would require zolmitriptan itself to be effective.  As a result, the district court found that a person skilled in the art would not have had a reasonable expectation of success in making a nasal formulation of zolmitriptan. 

The Federal Circuit found that the case was “close.”  But applying the deferential “clearly erroneous” standard, the Federal Circuit affirmed the district court’s factual findings, and thus affirmed its judgment of non-obviousness based on those findings.  The Federal Circuit noted that it was “especially persuaded” by the testimony supporting Astrazeneca’s teaching-away argument from one of Astrazeneca’s experts, whom the district court found to be more credible than Lannett’s experts.

This case is: IMPAX LABORATORIES INC. v. LANNETT HOLDINGS INC.

Edited by: Paul Stewart

Written by: Sabrina Wang and Christie Matthaei