Horizon Pharma, Inc.,a biopharmaceutical company,  has filed a patent infringement lawsuit in the United States District Court for the District of Delaware against Par Pharmaceutical, Inc. and related to an Abbreviated New Drug Application (ANDA) that Par filed with the US Food and Drug Administration (FDA) to market a generic version of Duexis tablets.

The lawsuit claims infringement of Horizon's US patent 8,067,033 that is listed in the FDA's Orange Book and expires July 18, 2026. Horizon received a Paragraph IV Patent Certification from Par on February 15, advising that Par had filed an ANDA with the FDA for a generic version of Duexis tablets. Par alleged that its generic version of Duexis tablets would not infringe US patent 8,067,033 or the patent is invalid or unenforceable. Par 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 proving bioequivalence. The defendants in the lawsuit are Par Pharmaceutical, Inc. and its parent Par Pharmaceutical Companies, Inc.

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

Horizon Pharma, Inc. is a biopharmaceutical company that is developing and commercializing innovative medicines to target unmet therapeutic needs in arthritis, pain and inflammatory diseases.