It?s business as usual for Indian pharmaceutical firms that lead the patent litigations chart for bettering their prospects in the regulated drug markets. Mumbai-based Sun Pharma entered into its second patent litigation in November, with the company and its US-based subsidiary, Caraco Pharma being sued by US major Schering Corporation for alleged infringement of the latter?s patent of the leading anti-allergic drug, Clarinex.

Earlier, Sun was sued by Finland-based Orion Corporation after the former sought marketing approval for a generic version of Orion?s drug Comtan, for treating Parkinson?s disease, in the US.

As FE had reported earlier, Sun Pharma and Dr Reddy?s Labs have entered into more patent litigations following more Para IV abbreviated new drug applications (ANDAs) filings with the USFDA, challenging the validity of the patented drugs concerned. The 180-day marketing exclusivity in the US, that will be granted if litigation is won, makes Para IV ANDA more attractive to generic firms.

Mark Pohl, a US patent attorney, said, ?The main benefit of patent challenge litigation is obtaining a 6-month monopoly on the generic market. Several years ago, however, MNCs began to launch their own generic if and when they lost a patent challenge. This second generic destroys the generic monopoly immediately. In doing so, it destroys the financial incentive – the potential profit – for patent challenge litigation.?

According to the documents submitted by Schering to the court, Sun had submitted ANDA 78-359 to the FDA seeking approval to engage in the commercial manufacture, use, offer for sale and sale of generic tablets containing 5 mg of desloratadine per tablet on June 21, 2006. Upon information and belief, ANDA 78-359, which was recently amended alleges that the claims of the ?223 patent are either invalid or not infringed by the manufacture, use or sale of its proposed generic version of Schering?s Clarinex. Upon information and belief, Schering received written notification of ANDA 78-359 and its new allegations on October 2, 2008.

A Sun Pharma spokesperson had said, ?Generic companies like ours file ANDAs on a regular basis, of which a few could be Para IV challenges. Commencing a litigation on an ANDA filing is the prerogative of the innovator company and not the generic firm.?

On July 29, 2008, the ?223 patent, titled ?Treating Allergic and Inflammatory Conditions,? was duly and legally issued to Schering as assignee.