Drug: pantoprazole magnesium dihydrate
In an NOC proceeding, Mylan has successfully alleged invalidity of Takeda's patent claiming the compound pantoprazole magnesium dihydrate.
Mylan made many invalidity allegations, but the patent was ultimately found invalid for anticipation. Mylan also alleged non-infringement, claiming their product does not infringe because it is a hemipentahydrate and not a dihydrate.
The anticipating document was a patent application that describes a process for preparing magnesium salts of certain benzimidazoles, including pantoprazole, that were known to be useful as gastric acid inhibitors. It was found that one of the examples to the patent necessarily produces pantoprazole magnesium dihydrate, even though the patent application did not state whether it produces a hydrous or anhydrous form.
The Court determined that the prior art example would anticipate the invention if it inevitably or necessarily produced the dihydrate. If a dihydrate is only sometimes obtained, then it would not anticipate.
Experimental testing was done by Mylan to show that if a skilled person followed the process in the example and characterized the obtained compound, they would find that it was the dihydrate. The patentee did not proffer any of its own testing to show that anything other than the dihydrate could be made using the process, and thus the Court held that the anticipation allegation was justified. The Court noted that although criticisms were made of Mylan's testing, not doing any testing in response was fatal to their arguments.
For the allegation of non-infringement, the Court found that the range of water content in Mylan's product fell between the theoretical water content of the dihydrate and the hemipentahydrate. This was not found to be sufficient to support a finding that Mylan's product is a dihydrate.