Mylan and Pfizer are in middle of a patent war regarding blockbuster drug – Norvasc, generically known as amlodipine besylate which worth around US $ 2.2 billion sales last year. Pressure will definitely be on Pfizer which will rigorously be defending its patent exclusivity on Norvasc valid till September 2007 (including pediatric exclusivity), as losing the trial could lead Mylan to penetrate amlodipine generic market sooner than expected. A bench trial which began yesterday before Judge Terrence McVerry is expected to last about a week. Mylan, which in October 2005 received FDA final approval for three dosage strengths of generic Norvasc, has admitted to infringing on Pfizer’s patent, but claims the patent is invalid and unenforceable. Till date, Mylan has not started marketing its generic version as it could face heavy damages if it started selling its product and then lost the patent trial to Pfizer. At yesterday trail, Dr. James I. Wells, a co-inventor of Norvasc, admitted that the patent application submitted for Norvasc contained an incorrect formula in reply to questions made by Mylan attorney (read more). For Mylan, wining the trial means getting a 180-day marketing exclusivity for generic version of Norvasc. Considering that Pfizer has already defended two similar patent infringement cases regarding Norvasc this year against Apotex (in January) and Synthon Laboratories (in August), Mylan must go on to continue firing legal canons!