Paddock Labs Wins Summary Judgment of Noninfringement in Univasc Suit Against Schwarz Pharma and Warner-Lambert

Judge Ann D. Montgomery of the U.S. District Court for the District of Minnesota recently granted Paddock Labs' motion for summary judgment of noninfringement of Warner-Lambert's U.S. Patent No. 4,743,450, which covers pharmaceutical formulations of moexipril hydrochloride, the active ingredient in Univasc.

Warner-Lambert granted Schwarz Pharma an exclusive license under the '450 patent to manufacture and sell drug products containing moexipril hydrochloride, an Angiotensin Converting Enzyme (ACE) inhibitor indicated for the treatment of hypertension and congestive heart failure.  Schwarz Pharma and Warner-Lambert sued Paddock Labs based on Paddock's ANDA to market a generic version of Univasc.  Schwarz Pharma's U.S. sales of Univasc amounted to $80 million last year.

In her opinion granting Paddock's motion for summary judgment, Judge Montgomery rejected Paddock's assertion of argument-based prosecution history estoppel, but agreed with Paddock's assertion of amendment-based prosecution history estoppel.  During prosecution, in order to overcome an obviousness rejection, Warner-Lambert amended claim 1 of the '450 patent from reciting an ACE inhibitor composition comprising "a metal containing stabilizer" to an ACE inhibitor composition comprising "an alkalai or alkaline earth metal salt."  Judge Montgomery found this was a narrowing amendment made for reasons of patentability, raising a presumption of surrender of all equivalents of "metal containing stabilizers" that are not "an alkalai or alkaline earth metal salt"--including magnesium oxide, the alleged equivalent Paddock uses in its generic Univasc formulation.

The court further found that the plaintiffs failed to rebut the presumption by proving either that magnesium oxide was an unforeseeable equivalent or that the claim amendment was merely tangentially related to magnesium oxide.  Accordingly, the court granted Paddock's motion for summary judgment of noninfringement.

In a last-ditch effort to avoid the finality of Judge Montgomery's opinion and order, last week Schwarz Pharma filed a motion to alter or amend judgment pursuant to FRCP 59(e).  In its motion, Schwarz argues that it was legally and factually erroneous for the court to conclude that magnesium oxide was a foreseeable equivalent.

UPDATE:  On Oct. 26, concurrent with its motion under FRCP 59(e), Schwarz Pharma filed a citizen petition asking the FDA not to grant final approval to Paddock Labs' ANDA until the district court rules on its motion.