On September 4, 2012, the Federal Circuit issued an opinion in
an appeal from the U.S. District Court for the District of
Delaware. Santarus, Inc., et al. v. Par Pharm., Inc., No.
2010-1360, -1380 (Fed. Cir. Sept. 4, 2012). Plaintiff Santarus is
the exclusive licensee of patents on specified formulations of
proton pump inhibitors (PPIs) used in the brand name drug Zegerid.
Par filed an Abbreviated New Drug Application (ANDA) seeking FDA
approval to sell generic Zegerid prior to the expiration of these
patents, thus invoking a patent infringement suit under the
Hatch-Waxman Act. The district court found that Par's ANDA
products infringed the patents, but held that the asserted claims
were not entitled to priority and that all of the asserted claims
were invalid for obviousness. In addition, the district court held
that certain claims were invalid for lack of written description.
The district court also found the patents enforceable.
The Federal Circuit affirmed the district court's ruling that
the patents were enforceable, reasoning that the inventor did not
commit inequitable conduct and, in particular, that intent to
deceive was not found. However, the Federal Circuit held that the
district court erred in finding (1) that the asserted claims failed
to meet the written description requirement; (2) that some of the
asserted claims were not entitled to priority; and (3) that some of
the asserted claims were obvious over the prior art. With respect
to the written description issue, the Federal Circuit held
specifically that the district court erred by holding that, when a
claim includes a negative limitation (i.e., "contains no
sucralfate"), it is necessary for the specification to include
evidence demonstrating that the negative limitation is
contraindicated. Rather, the majority stated that negative claim
limitations are adequately supported when the specification
describes a reason to exclude the relevant limitation. Such written
description support need not rise to the level of disclaimer.
With respect to the priority and obviousness issues, for those
claims for which Santarus appealed priority, the Federal Circuit
reversed and held that the claims were entitled to a priority
filing date and were not obvious over a parent patent. The primary
issue on appeal was whether a solid dosage form of non-enteric
coated PPI, such as omeprazole, would have been obvious to one of
ordinary skill in the art. The Federal Circuit concluded that the
prior art "ruled out" the use of non-enteric coated
conventional oral dosage forms such as tablets, capsules, or
granules so claims limited to those dosage forms were found valid.
The court nevertheless affirmed that the broader claims, not
limited to tablets, capsules or granules, were invalid.
Judge Newman dissented to three aspects of the majority opinion.
First, Judge Newman agreed that the district court erred in finding
no written description, but disagreed that negative claim
limitations only find written description support if the
specification states a reason to exclude the relevant limitation.
Second, Judge Newman stated that the panel majority created another
new ground of invalidity in holding that the common disclosure in a
parent patent is prior art to the chain of continuing patents.
Third, Judge Newman dissented to any finding of obviousness,
stating that the prior art and the expert witnesses were explicit
and uniform, that benzimidazole PPIs require an enteric coating for
practical oral administration to patients. There was no evidence
contrary to the position that an enteric coating was believed to be
necessary. This is a classic example of "teaching
away."
What This Means for You
Based on the majority opinion, there is now a question of whether negative claim limitations can only find written description support if the specification states a reason to exclude the relevant limitation.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.