Schwarz Pharma v. Paddock Labs, No. 2007-1074 (Fed. Cir. 2007)
In a decision released this morning, the Federal Circuit affirmed a 2006 district court decision granting summary judgment of noninfringement of U.S. Patent No. 4,743,450 in favor of Paddock Labs. The '450 patent, owned by Warner-Lambert and exclusively licensed by Schwarz Pharma, covers pharmaceutical compositions containing Angiotensin Converting Enzyme ("ACE") inhibitors, including Schwarz Pharma's Univasc (moexipril hydrochloride). ACE inhibitors are popular drugs for the treatment of hypertension and congestive heart failure. The Federal Circuit affirmed the district court decision "because the district court did not err in its conclusion that prosecution history estoppel bars resort to the doctrine of equivalents in this case."
Claim 1 of the '450 patent is directed to a pharmaceutical composition comprising an ACE inhibitor; "an alkali or alkaline earth metal carbonate"; and a saccharide. Claim 16, the only other independent claim of the '450 patent, is directed to a process for stabilizing an ACE inhibitor comprising contacting the drug with "an alkali or alkaline earth metal carbonate"; and a saccharide. Originally, the independent claims recited a "metal containing stabilizer" and "an alkali or alkaline earth-metal salt," respectively. However, following an obviousness rejection during prosecution, each was amended to recite "an alkali or alkaline earth metal salt carbonate." Paddock's ANDA products comprise an ACE inhibitor (moexipril chloride) and magnesium oxide (MgO).
As a preliminary matter, the Federal Circuit decided an issue concerning jurisdiction: whether Schwarz Pharma lacked standing to bring the appeal because Warner-Lambert, the patent owner, did not appeal the district court's judgment. Paddock argued that Schwarz was "merely an exclusive licensee of the '450 patent who does not possess 'all substantial rights' in the patent." While it is well established that a patent owner must be joined in an action for infringement brought by an exclusive licensee, the issue concerning appeals was one of first impression for the Federal Circuit. The court determined that "when a patentee joins an exclusive licensee in bringing a patent infringement suit in a district court, the licensee does not lose standing to appeal even though the patentee does not join in the appeal," explaining that the reason for requiring joinder in the district court (to avoid subjecting the alleged infringer to multiple actions) does not exist on appeal.
With regard to the patent issues, the Federal Circuit agreed with the district court that amendment-based prosecution history estoppel precluded Schwarz Pharma from resorting to the doctrine of equivalents to prove infringement. The court noted that the original claims recited a metal containing stabilizer and an alkaline earth metal salt, and therefore the subject matter encompassed by those terms was presumptively surrendered when the claims were amended. Schwarz Pharma argued, however, that the term "stabilizer" was defined in the specification more narrowly, to exclude MgO. But the Federal Circuit didn't buy it, since the "definition" in the specification wasn't so clear, and the ordinary meaning of "alkaline earth metal salt" encompasses MgO. The Federal Circuit further found that Schwarz failed to rebut the presumption of surrender because MgO was not an unforseeable equivalent and the narrowing amendment was not merely tangentially related to the use of MgO.
Paddock (and Teva, incidentally) is already on the market with its generic Univasc products, so as a practical matter, today's decision simply means that Paddock won't have to pay damages for past infringement and may continue to sell its products.
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