Addressing the validity and infringement of three patents in an Abbreviated New Drug Application (ANDA) case, the U.S. Court of Appeals for the Federal Circuit affirmed a decision of a lower court finding the patents not obvious and infringed.  The Court issued an injunction.  Pozen, Inc. v. Par Pharmaceuticals, Inc., Case Nos. 11-1584, -1585, -1586 (Fed. Cir., Sept. 28, 2012) (Wallach, J.) (Clevenger, J., dissenting-in-part).

The three patents-in-suit relate to the drug Treximet®—a combination of sumatriptan, a known 5-HT agonist effective against migraines, and naproxen, a known non-steroidal anti-inflammatory drug (NSAID).  Pozen developed a method of treating migraines using this combination and received approval from the FDA to market the drug.  The defendants filed ANDAs with the FDA seeking approval to market generic forms of the drug.  Thereafter, Pozen filed suit. 

The district court construed two important claim limitations.  First, the court construed “concomitant administration” to mean “simultaneous administration,” based on the patents’ use of the term “unit dose.”  Second, the court construed the term “substantially all” to mean “at least 90%, and preferably greater than 95%.”

After claim construction the district court held a bench trial, after which it found the claims valid and infringed and issued an injunction against the generic manufacturers.  The generics appealed.

On appeal, the Federal Circuit found that the prior art clearly disclosed a 5-HT agonist administered simultaneously with a NSAID, but did not disclose any additional details of the combination.  The Court found that the combination was not obvious because the prior art failed to disclose the relative success of the combination of reducing migraine relapse or producing longer efficacy or the dosage of the combination treatment.  Thus, even though the prior art taught the claimed combination, the Court held that there was no motivation to combine the two elements. 

The Federal Circuit, considering infringement, stated that the ANDA filings disclosed a multilayered tablet wherein each distinct layer contained 85 percent of either sumtripan or naproxen.  The Court found infringement of the “substantially all” limitation based on the doctrine of equivalents (DOE).  While recognizing precedent that the doctrine of equivalents cannot be relied on to broaden claims when a patentee has brought what would otherwise be equivalents of a limitation into the literal scope of the claim, the same was not true for the construed claim language.  Since the patentee never stated that the claims should be limited to the construed language, DOE was properly applied to find that 85 percent was an insubstantial change from 90 percent. 

The dissent argued that the majority failed to quantitatively evaluate whether 85 percent and 90 percent could be equivalent and further asserted that such equivalence would be impossible because they are “numerically nonequivalent.”