Horizon Pharma plc , a specialty biopharmaceutical company with a portfolio of products in arthritis, inflammation and orphan diseases, has filed a patent infringement lawsuit in the United States District Court for the District of New Jersey against Watson Laboratories, Inc. (WLF) and certain of its affiliated companies, Actavis, plc, and Actavis Inc., related to an Abbreviated New Drug Application (ANDA) that WLF filed with the US Food and Drug Administration (FDA) to market a generic version of Pennsaid (diclofenac sodium topical solution) 2% w/w (Pennsaid 2%).

The lawsuit claims infringement of US Patent Nos. 8,217,078; 8,252,832; 8,546,450; 8,563,613; 8,618,614; and 8,871,809 that are listed in the FDA's Orange Book with the latest patent term expiring on August 9, 2030. Horizon Pharma received a Paragraph IV Patent Certification from WLF on November 13, 2014, advising that WLF had filed an ANDA with the FDA for a generic version of Pennsaid 2%. WLF alleged that its generic version of Pennsaid 2% would not infringe the subject U.S. patents or the patents are invalid or unenforceable. WLF has not advised Horizon as to the timing or status of the FDA's review of its filing, or whether it has complied with FDA requirements for providing bioequivalence.

Horizon Pharma commenced the lawsuit within the 45 days required to automatically stay, or bar, the FDA from approving WLF's ANDA for 30 months or until a district court decision that is adverse to the subject patents, whichever may occur earlier.