By Donald Zuhn --
Last week, in Reckitt Benckiser Inc. v. Watson Laboratories, Inc. - Florida, the Federal Circuit affirmed a decision by the District Court for the Southern District of Florida holding that Defendant-Appellee Watson Laboratories, Inc. - Florida did not infringe the asserted claims of U.S. Patent No. 6,372,252. The Federal Circuit also determined that the District Court correctly construed the asserted claims of the '252 patent.
Plaintiff-Appellant Reckitt Benckiser Inc. markets bilayer tablets comprising guaifensin, an expectorant used to relieve congestion, as Mucinex®. Reckitt's bilayer tablets contain guaifensin in both immediate release (IR) and sustained release (SR) formulations. In obtaining FDA approval for its Mucinex® products, Reckitt listed the '252 patent in the Orange Book as covering the guaifensin tablets.
Seeking approval to market guaifensin tablet formulations, Watson filed an Abbreviated New Drug Application (ANDA) with the FDA. In response to Watson's ANDA filing, Reckitt brought suit against Watson for infringement of claims 24, 26-28, 31-34, 39, 57, and 58 of the '252 patent. Representative claim 24 reads (emphasis added by panel):
24. A modified release product having two portions, wherein a first portion comprises a first quantity of guaifenesin in an immediate release form which becomes fully bioavailable in the subject's stomach and a second portion comprises a second quantity of guaifenesin in a sustained release form wherein the ratio of said first quantity to said second quantity provides a Cmax in a human subject equivalent to the Cmax obtained when the first of three doses of a standard immediate release formulation having one third the amount of guaifenesin is dosed every four hours over a 12 hour period and wherein said product also provides therapeutically effective bioavailability for at least twelve hours after a single dose in a human subject according to serum analysis.
In construing the term "portion," which appears in each of the asserted independent claims, the District Court determined that the term means "a discrete part of the product." Following a bench trial, the District Court found that Watson's products, which are non-layered polymer matrix tablets made from a single guaifenesin formulation, do not have separate IR and SR portions, and therefore do not literally infringe the asserted claims of the '252 patent. The District Court also found no infringement under the doctrine of equivalents because Reckitt disclaimed products lacking two discrete structural portions during prosecution, and Watson's products lack two discrete structural portions.
In its opinion, the Federal Circuit noted that the prosecution history of the '252 patent was relevant to the parties' arguments on appeal. The Court pointed out that as originally filed, claims 1-11 were directed to a SR composition, claims 12-24 were limited to products with two portions, and claims 25-32 were directed to modified release tablets. In response to a rejection of claims 1-32 for obviousness, applicants cancelled the claims and added new claims 33-55, stating that the new claims were directed to "[a] modified release tablet having two portions," and adding that "the sustained release claims have been cancelled to facilitate prosecution." Applicants also distinguished the new claims over the cited prior art, stating that one reference "does not disclose a composition having both an immediate release portion . . . and a sustained release portion," and that the other reference, despite disclosing tablets with two separate portions, "specifically teaches away from employing any immediate realease portion."
On appeal, Reckitt argued that the District Court erred in construing "portion" and in finding no infringement either literally or under the doctrine of equivalents. In determining that the District Court did not err in construing the term "portion" to mean "a discrete part of the product," the Federal Circuit noted that:
The applicants disavowed claim coverage of sustained release tablets by cancelling original claims 1-11 and remarking to the examiner that "[o]riginal claims 1-11 were directed to a sustained release formulation . . . . [T]he sustained release claims have been cancelled to facilitate prosecution." The unmistakable effect of that disavowal, evident from the applicants' remarks distinguishing the prior art, was to limit the remaining claims to two-portion guaifenesin products [citations omitted].
The panel determined that "[t]he file history thus demonstrates a 'clear and unambiguous' prosecution disclaimer."
As for the District Court's finding of no infringement, the Federal Circuit stated that:
As the court correctly found, Watson's products do not infringe because they are non-layered, single-formulation polymer matrix tablets that do not contain the claimed "first portion" or "second portion." . . . The district court correctly concluded that Watson's products do not have two structural portions and that guaifenesin granules on the surface of Watson’s tablets do not constitute the claimed first portion of guaifenesin in an IR form.
With respect to infringement under the doctrine of equivalents, the panel concluded that:
[O]n the facts of this case, prosecution history estoppel bars Reckitt from recapturing single-formulation SR guaifenesin tablets like those it disclaimed in obtaining the '252 patent. As the district court correctly noted, Reckitt's narrowing claim amendments were made for reasons of patentability [citations omitted].
The Federal Circuit therefore affirmed the District Court's finding of no infringement, either literally or under the doctrine of equivalents.
Reckitt Benckiser Inc. v. Watson Laboratories, Inc. - Florida (Fed. Cir. 2011)
Panel: Circuit Judges Lourie, Linn, and Dyk
Opinion by Circuit Judge Lourie