Omeprazole Delayed Release 20 mg and 40 mg Capsules (Prilosec OTC): CAFC upheld Dr. Reddy’s non-infringement strategy

The Court of Appeal for Federal Circuit(CAFC) has affirmed (Here) a summary judgment decision by U.S District Court for the District of New York on Omeprazole Delayed Release 20 mg and 40 mg Capsules (Prilosec OTC), wherein, court has opined that generic player Dr. Reddy’s generic version of Prilosec OTC would not infringe innovator Astra Zeneca’s following Orange Book listed patents:

US5900424 (Assignee: Astra Aktiebolag; Date of grant: May 4, 1999; Expiry: May 4, 2016):

The said patent has following independent claims :

Claim 1. An omeprazole magnesium salt having a degree of crystallinity which is higher than 70% as determined by x-ray powder diffraction.

Claim 20. In a process for the manufacture of a crystalline magnesium salt comprising, (a) treating omeprazole or a salt thereof with magnesium alcoholate in a solution, (b) crystallizing magnesium omeprazole and (c) isolating the obtained crystalline magnesium omeprazole, wherein the improved process comprises separating inorganic salts from the reaction mixture prior to the crystallization step by the addition of water.

US5690960(Assignee: Astra Aktiebolag; Date of grant: November 25, 1997; Expiry: Nov 25, 2014): The said patent has following independent claims:

Claim 1. A stable oral formulation comprising: a core containing a magnesium salt of omeprazole said salt having more than 70% crystallinity as determined by x-ray powder diffraction; a subcoating layer; and an enteric coating layer, whereby the thickness of the enteric coating layer does not effect the release of omeprazole into solution at the pH predominantly present in the small intestine.

Claim 10. A process for the manufacture of a formulation of a pharmaceutical composition for the oral administration of magnesium omeprazole comprising the steps of: (a) forming a core material containing magnesium omeprazole salt said salt having at least 70% crystallinity as determined by x-ray powder diffraction; (b) applying in the presence of water at least one subcoating layer onto the core; (c) further applying in the pittance of water at least one enteric coating layer onto the subcoated core; and drying the prepared formulation.

Claim 22. An improved oral pharmaceutical composition containing a core of omeprazole salt with a subcoating and an enteric coating wherein the improvement comprises magnesium omeprazole salt having more than 70% crystallinity as determined by x-ray powder diffraction.

Discussion: After ANDA filing by Dr. Reddy with Paragraph IV certification with non-infringement grounds on above patents, innovator Astra sued generic player in U.S District Court for the District of New York for the infringement of above patents in July 27, 2007.

Further, innovator alleged that Dr. Reddy’s generic version will be covered under the scope of above patents. However, Dr. Reddy prepared the generic version which was amorphous with 1% crystalline content. Also, Dr. Reddy’s were not using water during crystallization process as covered in ‘424 patent.

However, innovator alleged that the generic version contains 5-8% of water, which would infringe the claim 20 of ‘424 patent. Further, during Markman hearing on disputed claim term by “the addition of water” the court opined that Dr. Reddy’s process has not used water during manufacturing the amorphous product and the said water can be attributed to atmospheric water adsorbed/absorbed on Dr. Reddy’s amorphous product or was prsent in the starting material used for the manufacturing of amorphous product.

In the light of above, U.S District Court for the District of New York issued Summary Judgment opinion in March, 2010 in favor of Dr. Reddy’s.