ST. LOUIS — Knoa Pharma and Knoa Pharmaceuticals have filed a patent-infringement lawsuit alleging that Humanwell Pharmaceuticals US Inc. and Epic Pharma LLC improperly sought federal approval to market generic versions of the extended-release opioid medicine Hysingla ER before four asserted patents expire.
The complaint, filed July 23 in U.S. District Court for the Eastern District of Missouri, Eastern Division, stems from an Abbreviated New Drug Application (ANDA) that Humanwell submitted to the U.S. Food and Drug Administration.
According to the lawsuit, the application seeks approval to manufacture, distribute, market, sell or import hydrocodone bitartrate extended-release tablets in 20-, 30-, 40- and 60-milligram strengths.
Knoa and its subsidiary contend that the proposed products would infringe U.S. Patent Nos. 8,808,740; 9,872,837; 9,770,416; and 9,775,809.
The plaintiffs are asking the court to find that the ANDA submission itself was an act of infringement, delay the effective date of any FDA approval until after the patents expire, permanently bar the defendants from commercially making or selling the proposed products before then and award damages if infringing products are commercially manufactured, used, sold or imported before the relevant patent expirations.
Hysingla ER is an FDA-approved oral extended-release hydrocodone bitartrate tablet used for management of pain severe enough to require daily, around-the-clock, long-term opioid treatment when alternative treatments are inadequate, according to the complaint.
The filing says the medicine is made with abuse-deterrent technology intended to make certain common forms of tampering, including crushing, breaking or dissolving, more difficult.
Knoa Pharma holds New Drug Application No. 206627 for Hysingla ER, which is sold in 20-, 30-, 40-, 60-, 80- and 100-milligram dosages. The company alleges that development and commercialization of the product required substantial investment and scientific innovation to achieve its abuse-deterrent properties.
The lawsuit says Humanwell sent a notice of Paragraph IV certification on June 9.
Under that certification, Humanwell asserted that the four patents, among others, are invalid, unenforceable and/or not infringed by the proposed generic products.
The complaint says Humanwell’s notice letter reported that its ANDA relied on the Hysingla ER application and included data from bioavailability or bioequivalence studies comparing the proposed products with Hysingla ER.
Knoa and Knoa Pharmaceuticals filed the action within 45 days of receiving the notice letter, the complaint says, and contend that they are therefore entitled to a stay of FDA approval under federal law.
The complaint also states that, on information and belief, the FDA had not approved Humanwell’s ANDA at the time of filing.
The plaintiffs allege that the proposed generic tablets fall within claims of the four patents, which cover tamper-resistant controlled-release dosage forms and pharmaceutical compositions involving hydrocodone, polyethylene oxide and specified manufacturing or performance characteristics.
The complaint alleges that Humanwell and Epic intend to make, market, distribute, sell or import the products immediately upon FDA approval.
Knoa Pharma states in the filing that it owns the four patents. The complaint says the relevant rights were transferred after Purdue permanently ceased operations on May 1. The patents for Hysingla ER are listed in the FDA’s publication, commonly known as the Orange Book, according to the lawsuit.
The plaintiffs are seeking an injunction and damages for infringement. They are represented by Stacey R. Gilman and Stephan K. Skepnek of Berkowitz Oliver and Matthew Moore, Marc Zubick and Manuela Burek of Latham & Watkins.
U.S. District Court for the Eastern District of Missouri, Eastern Division case number: 4:26-cv-01170
