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Executive Summary

DANBURY/SCHEIN CYCLOBENZAPRINE LAUNCH SET FOR MAY 15, following a decision by the federal patent appeals court, which ruled on May 2 that Merck's Flexeril patent is valid but unenforceable. Affirming a Delaware Federal Court decision, the Court of Appeals for the Federal Circuit determined that the lower court did not abuse its discretion in declaring the Flexeril patent unenforceable for having been inequitably procured. The ruling upholds Danbury's challenge of Merck's patent, which was scheduled to expire in 1992. Danbury received on Oct. 31, 1986 FDA's prospective approval for its cyclobenzaprine ANDA, which was submitted with a certification (claim) of non-infringement. The decision gives Danbury a six-month period as the exclusive marketer of generic cyclobenzaprine ("The Pink Sheet" Oct. 3, T&G-9). The three-judge panel comprised Chief Judge Howard Markey, who wrote the opinion, and Circuit Judges Edward Smith and H. Robert Mayer. Their ruling also affirms the lower court's award of attorney's fees to Danbury. "Merck's brief attacks the award only on the ground that the inequitable conduct determination is wrong," Judge Markey wrote. "That attack having failed, we affirm the award." Merck said it "strongly disagrees with the finding of unenforceability" but has "exhausted legal remedies and will not be able to enforce our U.S. patent rights on Flexeril, which is Merck's 14th largest selling product." The product has sales of roughly $ 100 mil., according to analyst estimates. The appeals court agreed with the lower court finding that, when applying for its patent, Merck withheld from the Patent & Trademark Office information about the similarity of cyclobenzaprine to an earlier drug product, amitriptyline (Merck's Elavil). The withheld information was material and "would clearly have been important to a reasonable [PTO] examiner," the opinion states. "The district court correctly found" that amitriptyline's activity was comparable to cyclobenzaprine's. The CAFC also disagreed with Merck that its misrepresentation in telling the PTO that Flexeril does not cause drowsiness was immaterial. Merck argued that drowsiness is unrelated to the product's unique selectivity as a muscle relaxant that does not cause central nervous system effects. The lower court ruled that Flexeril "produces sedative effects, although not muscle weakness" and that its "selectivity is limited to its operation without loss of muscle tone." The CAFC decided: "Merck has not shown that finding to have been clearly erroneous or that the district court abused its discretion in so viewing the evidence." Regarding Merck's contention that it did not intend to mislead the PTO, the appeals court said: "We cannot say that the [lower] court's finding of intent to mislead was clearly erroneous. Nor can we conclude that the court abused its discretion in determining that Merck was guilty of inequitable conduct." The opinion cites Merck's "simultaneous submission of amitriptyline data to FDA and its withholding from the PTO" and "the material misrepresentation to the PTO" of Flexeril's drowsiness effect."

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