Just days after filing for chapter 11 bankruptcy, Dublin-based Endo International was dealt another blow. The company has lost a patent infringement lawsuit, and, now, its top-selling blood pressure drug Vasostrict will face generic competition.
Endo has been fighting off a generic from Eagle Pharmaceuticals since 2018, when it sued Eagle after the FDA approved its Vasostrict generic. Endo's drug is distributed by its unit Par Pharmaceutical, and a July 2021 trial ruled that Eagle's generic did not infringe any of Par’s patents. Par quickly appealed that decision, and the second trial, which was held last month, upheld the original ruling of non-infringement.
Par’s arguments centered around the pH level of the drug, arguing that while the nominal pH range of Eagle’s generic does not overlap with Par’s pH range claimed under patents, real-world evidence demonstrated that the pH of Eagle’s drug “drifts up over time.” Coupled with its argument that Eagle had sought authority to release products with a pH of 3.64, which is just 0.01 beneath the infringing range claimed by Par, the company attested that Eagle’s drug would “more likely than not” infringe Par’s patents.
However, the district court disagreed, finding after a three-day bench trial that “minor fluctuations” in pH value did not reveal any discernible trend, let alone a “steady and inevitable” upward drift, the court’s ruling stated. Par contended that the FDA “cannot ensure” that every product on the market by Eagle will comply with the pH stability specification, yet Eagle acknowledges that it is bound by its representations to the FDA that its products must have a pH between 3.4 and 3.6 throughout its shelf-life, “not just at release.”
“Par’s unsupported conjecture that Eagle will not abide by its representations is inadequate to establish infringement,” the court stated in its ruling.
Eagle began marketing the product in question this January, adding to Endo's opioid related cash struggles. Just last week, Endo agreed to pay $450 million over 10 years in an opioid settlement with 36 states, plus $2.75 million for archival expenses. The settlement resolved allegations that the company falsely marketed opioids.