U.S. a Court of Appeals For federal circuit (CAFC) Upheld an infringement finding against generic Players Apotex and Impax on Wednesday in a case brought by AstraZeneca to defend the following formulation patents for its popular heartburn drug Prilosec (Omeprazole).
US4786505 (expiry: Oct 20, 2007): which covers an oral pharmaceutical preparation comprising (a) a core region comprising an effective amount of a material selected from the group consisting of omeprazole plus an alkaline reacting compound, an alkaline omeprazole salt plus an alkaline reacting compound and an alkaline omeprazole salt alone; (b) an inert subcoating which is soluble or rapidly disintegrating in water disposed on said core region, said subcoating comprising one or more layers of materials selected from among tablet excipients and polymeric film-forming compounds; and (c) an outer layer disposed on said subcoating comprising an enteric coating.
US4853230 (expiry: Oct 20, 2007): which covers an pharmaceutical preparation comprising: (a) an alkaline reacting core comprising an acid-labile pharmaceutically active substance and an alkaline reacting compound different from said active substance, an alkaline salt of an acid labile pharmaceutically active substance, or an alkaline salt of an acid labile pharmaceutically active substance and an alkaline reacting compound different from said active substance; (b) an inert subcoating which rapidly dissolves or disintegrates in water disposed on said core region, said subcoating comprising one or more layers comprising materials selected from the group consisting of tablet excipients, film-forming compounds and alkaline compounds; and (c) an enteric coating layer surrounding said subcoating layer, wherein the subcoating layer isolates the alkaline reacting core from the enteric coating layer such that the stability of the preparation is enhanced.
Impax tried to prove non-infringement on various grounds first that their formulation do not contain inert core, and the application of disputed patent was filed after one year of discovery, there is no article III controversy as disputed patents has expired. However, court refuted all the claims of Impax w.r.t noninfringement and inavlidty of disputed patents.
Earlier, CAFC in a decision in June 2008 gave favorable non-infringement opinion to another generic player Mylan’s as reported earlier by IPPHARMADOC Here
Mylan successfully designed around against innovator Astra’s Orange Book listed patents by using Talc in the coating. However, non-infringement strategy adopted by Apotex and Imapx was infringing and District court as well as CAFC upheld infringement.
Apotex’ formulation contains pallets with Povidone (PVP), magnesium hydroxide and mannitol. Apotex applies to pallet core an enteric coating of water, Methacrylic acid copolymer (MACP) and triethyl citrate. This strategy as per Apotex was non-infringing as there was no sub coat is involved but the testimony of innovator's expert Dr Davies led to the conclusion that reaction of PVP and MACP resulted into the formation of subcoat which was confirmed by Confocal laser scanning microscopy (CLSM). The expert successfully proved in the court that subcoat is present in Apotex formulation.
Regarding claim construction of disputed terms, specifically the meaning of the term alkaline Reacting compound (ARC) and acid labile. The CAFC rejected Apotex's claim that ARC was limited to salts from Groups I and II of the periodic table, finding that it was contrary to the specification of the '230 patent and claim 8, which included within the scope of the term ammonium salts also. Further, the term acid labile, the Court interpreted the cited prior art to disclose acid-stable compounds that did not anticipate the claims at issue.
Also, generic player’s attempt to invalidate formulation patents of Astra in the light of KSR v.s Teleflex decision and strong prior art was not accepted by the court
Importantly, the disputed patents have already expired.
As the generic manufacturer has entered into the market at risk since last five years, the decision allows AstraZeneca to seek compensation from Impax, Apotex and Impax's partner, Teva, for any sales they made when the patents were in force.
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