Endo loses Vasostrict patent battle as sales take a hit from generics
It’s been just two days since Endo International filed for bankruptcy in an attempt to dig itself out of thousands of opioid lawsuits. Now one of its top sellers is in trouble.
A federal appeals court on Thursday affirmed a Delaware judge’s decision that Eagle Pharmaceuticals’ generic version of Endo’s vasopressin injection Vasostrict does not infringe on the company’s patents. Eagle’s version won approval back in December, and already, the generic and others like it have driven down Vasostrict sales.
Vasostrict is manufactured by Endo’s Par Pharmaceutical unit, and raked in a whopping $900 million last year, more than doubling the earnings of Endo’s second highest-selling product, Xiaflex for men with Peyronie’s disease.
Even though vasopressin has been marketed as a therapeutic agent for almost a century, Par won approval back in 2014 as part of an FDA initiative to encourage manufacturers to get approval for old, unapproved drugs. The drug is approved to increase blood pressure in adults with vasodilatory shock who remain hypotensive despite fluids and catecholamines.
However, sales last quarter took an 85% dive from Q2 2021 due to “lower price and market share resulting from generic competition,” the company said.
In addition to Eagle, Dr. Reddy’s and Amphastar have also swung approvals for their own generic versions.
Par filed suit against Eagle back in 2018, around the same time that Eagle submitted its ANDA. Plaintiffs argued that the generic would infringe on two patents, which expire in 2035 and require vasopressin to have a rounded pH between 3.7 and 3.9. However, a Delaware court ruled last August that Eagle’s product doesn’t overstep because its pH range is below that covered by the Par patents.
While acknowledging the lower pH of Eagle’s generic, Par pointed to evidence that the pH of Eagle’s product would drift up over time, infringing on the patents.
A federal appeals court maintained the initial court’s decision on Thursday, noting:
The district court’s finding that there was no upward pH drift in Eagle’s post-release pH data was not clear error. The court thoroughly considered the post-release pH data Par cites, along with Eagle’s expert testimony assessing that data, and found that, while the pH measurements fluctuated over time, there was no discernable trend — and certainly not an inevitable upward trend — in the fluctuations.
Endo has declined to comment.
The news comes days after Endo filed for bankruptcy under a mountain of opioid lawsuits, following in the footsteps of Purdue Pharma and Mallinckrodt. The company faced a litany of complaints over its former opioid pain med Opana ER, which was taken off the market in 2017 at the FDA’s request.
Endo filed for a Chapter 11 on Wednesday, while also reaching a $450 million opioid settlement with several states.