Federal Circuit Again Rules Equivalent Foreseeable in Duramed
In Duramed, the invention claimed in U.S. Pat. No. 5,908,638 (the “’638 patent”) involved a conjugated estrogen pharmaceutical compositions for use in hormone replacement therapies. The critical aspect of the claimed invention was the moisture barrier coating (MBC) which surrounded the composition. Claim 7 (which depended from independent Claim 1) specified that this MBC “comprises ethylcellulose.” During patent prosecution, the examiner rejected both Claims 1 and 7 for obviousness under 35 U.S.C. § 103. As a result of an interview with the examiner, Claim 1 was amended to include the recitation in Claim 7, and in due course, the ‘638 patent issued. Sounds to me like a classical instance of prosecution history estoppel coming into play and barring any application of the doctrine of equivalents.