Bayer Schering Pharma AG v. Barr Labs., No. 05-2308 (D.N.J. 2008)
On Monday, the U.S. District Court for the District of New Jersey invalidated
Bayer's U.S. Patent No. 6,787,531
on grounds of obviousness, relying heavily on KSR. The '531 patent,
claiming pharmaceutical formulations of micronized drospirenone and
ethinylestradiol, protects Bayer's Yasmin birth control pill.
Barr Labs had challenged the '531 patent in a paragraph IV certification with
its ANDA filing.
The court's opinion
follows a bench trial held over a two-week period late last year. The main
issues in the case were whether it would have been obvious "to (1) micronize
drospirenone so as to increase its bioavailability, and (2) not protect the
drospirenone from the gastric environment with an enteric coating."
Drospirenone is a relatively difficult molecule to formulate due to its poor
water solubility and sensitivity to acid.
While Bayer argued that the prior art taught away from micronizing
acid-sensitive drugs like drospirenone, the court concluded: "Undoubtably, there
would be some concern about dissolution of a poorly water soluble acid sensitive
drug, but the person of ordinary skill in the art could conclude that
micronization is a viable option." Similarly, while Bayer asserted that the
prior art taught that acid sensitive drugs must be enteric coated, the court
credited Barr's argument, finding that "inter- and intra-subject variability is
a major disadvantage" of enteric coating, and concluding therefore that one
"could not rule out formulating a micronized drospirenone without enteric
coating." Furthermore, the court concluded that a prior art reference teaching
that drospirenone isomerzies when exposed to hydrochloric acid in vitro
(Nickisch) should be discounted because its results were not corroborated by in
vivo studies.
In addition to concluding that the invention claimed in the '531 patent would
have been obvious, the court concluded that the invention was obvious to
try:
As noted, in KSR the Supreme Court ruled that a patent claim may be obvious
if the combination of elements was "obvious to try." In this case, the
testimony was limited to discussion about whether or not to employ to common
formulation techniques — micronization and enteric coating. As in KSR "there
are a finite number of identified predictable solutions." In this case, based
on the prior art as a whole, micronizing and immediately releasing drospirenone
was obvious to try.
The '531 patent, which would expire in 2020, is one of three Orange Book-listed patents for Yasmin. The others are U.S. Patent No. 5,569,652, claiming methods of use and expiring in 2013; and U.S. Patent No. 6,933,395, claiming compositions and expiring in 2017. Although Barr is the first ANDA filer for a generic version of Yasmin, if Barr filed paragraph III certifications with respect to the '652 and '395 patents, then it must wait at least until those patents expire before it launches its generic product.
The U.S. market for Yasmin is approximately $500 million annually. Bayer is expected to appeal Monday's decision to the U.S. Court of Appeals for the Federal Circuit.
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