Federal Circuit Finds Prosecution History Estoppel Prevents Coverage of Equivalent Since Amendment Was Foreeseable Equivalent

In Duramed Pharmaceuticals, Inc v Paddock Labritories, Inc., 644 F3d 1376, 99 USPQ2d 1388 (Fed. Cir. 2011), Duramed (now known as Teva Women’s Health Inc.) owns U.S. Patent No. 5,908,638 (‘638 patent.), which is directed to estrogen pharmaceutical compositions.  When originally filed, original independent claim 1 recited a conjugated estrogen pharmaceutical composition “coated with a moisture barrier coating,” and original dependent claim 7 limited “said moisture barrier coating” to one that “comprises ethylcellulose.”  During prosecution, the examiner rejected both claims for obviousness.  However, after an interview, the Examiner indicated that if the limitation of claim 7 was included the independent claim 1, it would be allowed. Duramed amended claim 1 to include the limitation, and the claim was allowed.  Thus, claim 1 of the issued ‘638 patent claimed pharmaceutical compositions for hormonal treatment of pre-menopausal, post-menopausal, and menopausal disorders with “a moisture barrier coating comprising ethylcellulose.”

In 2009, Duramed brought suit against Paddock under 35 U.S.C. §271(e)(2) for infringement of  the ‘638 patent. Paddock had proposed in an Accelerated New Drug Application for a generic version of Duramed’s hormone replacement utilizing polyvinyl alcohol (PVA) for a moisture barrier coating (marketed as Opadry AMB.)  Duramed asserted that the generic version infringed claims 1, 4, and 6-8 under the doctrine of equivalents because Paddock’s proposed generic product uses a polyvinyl alcohol (“PVA”) MBC, marketed as Opadry AMB. Paddock moved for summary judgment of noninfringement, arguing that Duramed was barred by amendment-based prosecution. Continue reading