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Pfizer Wins Dismissal of Ranbaxy's Counterclaims in Caduet Patent Litigation

By Aaron Barkoff

Pfizer v. Ranbaxy, No. 07-138 (D. Del. 2007)

Pfizer sued Ranbaxy for infringement of U.S. Patent Nos. 4,681,893 and 6,455,574 after Ranbaxy filed paragraph IV certifications in its ANDA for a generic version of Caduet (atorvastatin calcium/amlodipine besylate).  The '893 patent claims atorvastatin calcium, which is also the active ingredient in Lipitor; the '574 patent claims combinations of atorvastatin sodium and amlodipine besylate.  Ranbaxy filed counterclaims seeking declaratory judgments that (1) the '893 patent is invalid; (2) the '574 patent is invalid and not infringed; and (3) a third patent, U.S. Patent No. 5,273,995, is invalid, unenforceable and not infringed.  In an opinion filed November 29, the district court granted Pfizer's motions to dismiss Ranbaxy's counterclaims on the '893 and '995 patents, leaving only the '574 patent in the case.

On August 2, 2006, the Federal Circuit affirmed the validity of the '893 patent in Pfizer's case against Ranbaxy concerning Ranbaxy's ANDA for a generic version of Lipitor.  Ranbaxy appealed to the Supreme Court, and in April, the Court denied Ranbaxy's cert petition.  Accordingly, in the Caduet litigation, Pfizer moved to dismiss Ranbaxy's counterclaims of invalidity of the '893 patent on grounds of res judicata.  In addition, Pfizer moved for partial summary judgment on the pleadings, asking for a judgment of infringement of the '893 patent on grounds of collateral estoppel.

In opposition to Pfizer's motion, Ranbaxy argued that res judicata principles should be narrowly applied because the issue of obviousness was not presented at trial or adjudicated in the Lipitor litigation, and "significant factual and legal changes have occurred since the Lipitor litigation that fundamentally alter the obviousness analysis of the '893 patent."  Specifically, Ranbaxy argued that the Supreme Court's decision in KSR v. Teleflex "dramatically lowered the bar of 35 USC 103."  The district court, however, was unconvinced, stating that Ranbaxy challenged the validity of the '893 patent in the Lipitor litigation, and therefore, absent fraud or a momentous legal change in constitutional rights, "Ranbaxy was required to raise all of its invalidity defenses at that time."  Thus, the court granted Pfizer's motion to dismiss.  In addition, because Ranbaxy did not contest infringement of the '893 patent, the court granted Pfizer's motion for a judgment of infringement of the '893 patent on the pleadings.

In the same August 2, 2006 decision, the Federal Circuit held that Claim 6 of the '995 patent is invalid.  The '995 patent covers pharmaceutical compositions containing atorvastatin calcium.  Pfizer is currently seeking a reissue of the '995 patent to correct the defect in Claim 6 and to correct defects in other claims.  In the Caduet litigation, Pfizer moved to dismiss Ranbaxy's counterclaims on the '995 patent on grounds that it has provided Ranbaxy a covenant not sue Ranbaxy on all remaining claims of the original '995 patent.

In response to this motion, Ranbaxy argued that its declaratory judgment counterclaims of unenforceability of the '995 patent should not be dismissed, notwithstanding Pfizer's covenant not to sue, because "Pfizer has not agreed to provide Ranbaxy with a covenant not to sue related to any reissue of the '995 patent."  Here too, however, the district court was unconvinced by Ranbaxy's arguments.  The court stated:  "the question of whether a new patent will ever be reissued is speculative, purely hypothetical and unripe for judicial determination.  Accordingly, the Court concludes that these circumstances do not support jurisdiction under the MedImmune standard."

As a result of the district court's decision, Ranbaxy will not be able to launch its generic version of Caduet until at least 2010, when the '893 patent expires.  Pfizer will now proceed with the case, aiming to keep Ranbaxy off the market until 2018, when the '574 patent expires.

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Full post as published by Orange Book Blog: At the Intersection of Patent Law and FDA Law on December 12, 2007 (boomark / email).