Duramed Parmaceuticals (Teva Women's Health) v. Paddock Labs. (Fed. Cir. 2011)
By Dennis Crouch
Note: This case supports the already accepted notion that the presumptive bar to the doctrine of equivalents created by a narrowing amendment during patent prosecution is very difficult to overcome.
Teva is the largest worldwide manufacturer of generic drugs. In this case, however, the tables are turned. In 2008, Teva purchased Barr and its subsidiary Duramed. In 2009, the company sued Paddock – alleging that the defendant's application with the FDA to distribute a generic estrogen-derived hormone replacement constituted patent infringement under 35 U.S.C. § 271 (e)(2)(A).
(2) It shall be an act of infringement to submit - (A) an application under section 505(j) of the Federal Food, Drug, and Cosmetic Act … for a drug claimed in a patent or the use of which is claimed in a patent.
The asserted patent – No. 5,908,638 – covers Duramed's Cenestin ERT product and appears to be set to expire in 2015.
Narrowing Amendment: During prosecution of the patent, Duramed amended narrowed its claim 1 in response to an office action rejection. The amendment took a limitation from a dependent claim and added it to claim 1 so that the independent claim now required that the pharmaceutical composition be "coated with a moisture barrier coating comprising ethylcellulose."
In its abbreviated new drug application (ANDA), Paddock indicated its plans to use a barrier made of polyvinyl alcohol rather than ethylcellulose. So, when it sued, Duramed alleged infringement under the doctrine of equivalents (DOE).
Festo and Prosecution History Estoppel: The district court rejected the DOE claim – holding that Duramed was barred from claiming equivalents over the ethylcellulose coating based upon the doctrine of prosecution history estoppels. (Citing Festo).
On appeal, the Federal Circuit affirmed – holding that the district court had properly ruled the patent not infringed.
A patent is literally infringed only when the accused action or device meets all of the elements of the invention as defined by the patent claims. Long ago, courts added some leeway to the infringement analysis through the Doctrine of Equivalents. Through application of the DOE, infringement can be found even when the accused device is outside of the literal scope of a patent claim – so long as there is "equivalence between the elements of the accused product or process and the claimed elements of the patented invention." Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17 (1997).
DOE and PHE: The courts have limited the DOE in a number of ways. One of the most important limitations is that of prosecution history estoppel (PHE). In Festo and other cases, the courts held that it would be unfair to allow a patentee to use the DOE to recapture patent scope that had been voluntarily surrendered in order to acquire the patent.
The process for determining whether prosecution history estoppel applies first asks whether estoppels presumptively applies and then asks whether the patentee can overcome the presumption. Thus:
- PHE is presumed when a patent claim is narrowed for reasons relating to patentability;
- However, the presumption can be overcome by showing that the patentee did not intend to surrender the particular equivalent.
In Festo, the Supreme Court offered two specific arguments that could be used to overcome the presumption: (1) that the alleged equivalent would have been unforeseeable at the time the amendment was made; and (2) that the reason for the amendment only tangentially related to the equivalent in question. In addition, the Supreme Court noted that other explanations may also work to overcome the presumption.
Here, the Federal Circuit agreed that the presumption of PHE applied because Duramed had narrowed its claims in response to a prior art rejection. The court also agreed that Duramed had failed to overcome the presumption. In particular, the court held that the polyvinal alcohol alternative should have been foreseeable because it was already known to be used in other pharmaceutical compositions.
What is Foreseeable?: Courts will find an alternative "foreseeable" if it is known in the prior art pertinent to the claim scope before the amendment. This definition means that a foreseeable alternative is somewhat more broadly defined than is an obvious alternative. Here, Duramed argued that it was not foreseeable at the time of the amendment to use the polyvinal alcohol alternative in combination with the estrogen drug. On appeal, the Federal Circuit held that foreseeability for PHE analysis does not require such precision – rather, it was sufficient for the court that the alternative was known for use with other pharmaceutical compounds.
As we spelled out in Schwarz, when the language of both original and issued claims begins with the words "[a] pharmaceutical composition," that language defines the field of the invention for purposes of determining foreseeability. Accordingly, PVA MBCs need only to have been known in the field of pharmaceutical compositions as of the time of Duramed's narrowing amendment. . . . [F]oreseeability does not require such precise evidence of suitability. And even if the [prior art] disclosure indicates that PVA is less than ideal in some pharmaceutical uses as an MBC, it is still disclosed to be useful as such, and that renders it foreseeable for purposes of prosecution history estoppel. Foreseeability does not require flawless perfection to create an estoppel.
Because Duramed was unable to overcome the presumption, prosecution history estoppels applies to bar Duramed from asserting that the accused Polyvinal alcohol barrier is equivalent to the claimed ethylcellulose barrier.