Glaxo sued Barr over Argatroban injection

GSK, Mitsubishi and Encysive Pharma have filed a patent infringement lawsuit to stop Barr Laboratories from producing a generic version Argatroban injections.The suit was filed on Dec. 28 in the U.S. District Court for the Southern District of New York after Barr submitted an ANDA, with the USFDA to market a generic version of the injections.Argatroban is approved by the FDA to treat thrombocytopenia induced by popular blood thinner Heparin. The drug is also used in patients undergoing heart procedures.Encysive holds the approved NDA for Argatroban and has licensed the North American marketing rights for the drug to GlaxoSmithKline. Mitsubishi Chemical, whose pharmaceutical arm Mitsubishi Tanabe Pharma Corp. is also named as a plaintiff in the suit, holds US5214052 (which covers method for dissolving an arginineamide, comprising: dissolving 2-arylsulfonyl-L-argininamide and/or its salt in a solvent containing ethanol, water and a saccharide) for the injection.Barr filed its ANDA with the FDA in September 2007. Two months later, Barr notified Encysive of its application, which seeks marketing approval before Mitsubishi Chemical's patent expires in June 2014.Barr claims the patent is invalid, unenforceable and would not be infringed by its manufacture and sale of a generic copy. Barr's invalidity claims are based on a prior European patent application and a paper published in the Journal of the American Pharmaceutical Association in 1951.“Beyond summarily claiming that 'the '052 patent is invalid, unenforceable, and/or will not be infringed by the proposed product, Barr does not specifically assert that the '052 Patent is unenforceable, and the letter does not provide any factual or legal basis for an assertion that the '052 patent is unenforceable, as required by applicable law,” the complaint said.Barr believes it is the first company to file an ANDA containing a paragraph IV certification for Argatroban. If the FDA approves the application, Encysive would have a 180-day exclusive window to market generic Argatroban.Encysive said the lawsuit would automatically stay the FDA from approving Barr's ANDA for 30 months unless modified by the court.The patent, titled “Method for dissolving arginineamides and pharmaceutical compositions containing them,” was issued in May 1993 and assigned to Mitsubishi Chemical. Encysive's New Drug Application was approved by the FDA in June 2000.Barr said that the Argatroban injection product produced sales of $111 million in the U.S. for the 12 months ended October 2007, based on IMS sales data.