Pantoprazole Sodium Delayed Release (DR) Tablets: The CAFC upheld District court’s decision

The U.S. Court of Appeals for the Federal Circuit (CAFC) unanimously affirmed a September 2007 ruling by US district Court for the district of New Jersey, which denied a motion filed by innovator Wyeth and Altana for a preliminary injunction related to generic launch of Pantoprazole Sodium Delayed Release (DR) Tablets by generic players like Teva, Sun pharma and Schwarz paharma.

Earlier, district court denied Altana preliminary injunction based on strong invalidity argument developed by generic companies w.r.t Altana’s Orange Book listed product patent US4758449 (Expiry: Jul, 2010). The generic companies alleged that innovator’s patent on Pantoprazole which is chemically 6-(difluoromethoxy)-2-[(3,4-dimethoxypyridin-2-yl)methylsulfinyl]-1H-benzo[d]imidazole is obvious in the light of following strong prior art:

1) US4255431: product patent on Omeprazole which discloses various structural features for optimal Proton pump inhibitory (PPI) activity

2) US4555518: disclosed 18 PPI compounds and compund number 12 exhibit structural similarity with Pantoprazole. Further, compound 12 differ from pantoprazole in terms of difference in substituents at 3 position of pyridine ring. Pantoprazole has methoxy group while compound 12 of ‘518 patent contains methyl group.

3) Article by Sachs, Brysnon and ‘431 patent on PPI which shows various structural features for optimal PPI activity like Benzimidazole ring, pyridine ring, methyl sulfinyl groups. Also, these articles describe that methoxy group at pyridine ring lowers Pka value (to about 4) of PPI and exhibit optimal PPI activity.

Based on above elements district court opined the vulnerability of ‘449 on obviousness standards and denied preliminary injunction. Subsequently, Altana appealed in CAFC based on following points:

1. District court’s failure to take into account an accused infringer’s clear and convincing burden to prove invalidity

2. District Court’s selection of compound 12 (US4555518) as lead compound

3. District court’s interpretation of Sachs, Brysnon articles

Further, The CAFC upheld District court’s decision and opined that elements considered by lower court while denying preliminary injunction were correct.

Opinion of court Here