Amneal can release CaroSpir generic, says judge
Amneal Pharmaceuticals fends off CMP’s US lawsuit alleging infringement of the blood pressure treatment | Dispute centres on whether suspension agents were used in “substantially the same way”.
Amneal Pharmaceuticals has won a patent dispute brought before it by rival CMP Development for alleged infringement of three patents.
In an opinion handed down on September 29, the Delaware court concluded that CMP failed to show that Amneal’s ANDA product would infringe the asserted claims of its US patents (numbers 10,624,906; 10,660,907; and 10,888,570).
Amneal filed an Abbreviated New Drug Application (ANDA) with the US Food and Drug Administration (FDA), seeking approval to market a generic version of CMP’s blood pressure treatment CaroSpir before its associated patents expired.
All three patents are titled “Spironolactone Aqueous Compositions”, and describe a ready-to-use liquid formulation comprising spironolactone.
CMP’s CaroSpir is a ready-to-use liquid oral suspension with spironolactone as the active pharmaceutical ingredient. It is prescribed to patients who have difficulty swallowing, or who cannot swallow tablets, to treat heart failure, hypertension and edema caused by cirrhosis.
The Hatch-Waxman action centres on whether the different suspending agents, used in each version to increase viscosity in their respective suspensions, work in “substantially the same way”.
While CaroSpir contains xanthan gum as a suspending agent, Andeal’s generic uses tragacanth powder—which CMP argues is the equivalent of xanthan gum.
Endorsed tests
Judge Maryellen Noreika wrote that analysis under the doctrine of equivalents follows one of two tests endorsed by the Supreme Court—the function-way-result test or the insubstantial differences test—both of which are performed on an element-by-element basis.
The function-way-result test evaluates whether the element in the accused product performs substantially the same function, in substantially the same way, to achieve substantially the same result as the claimed element.
Under the insubstantial differences test, “[a]n element in the accused device is equivalent to a claim limitation if the only differences between the two are insubstantial.”
The court agreed with CMP’s assertion that Amneal’s ANDA product meets the claim limitation “from about 0.18% w/v to about 0.36% w/v of a xanthan gum” under the doctrine of equivalents.
The court also agreed with Amneal’s counter-argument that CMP failed to meet its burden to show that (a) tragacanth powder is the equivalent of xanthan gum and (b) the amount of tragacanth powder in the ANDA product is the equivalent of the claimed amount of xanthan gum in the patented invention.
The opinion was filed at the US District Court for the District of Delaware.
Attorneys for CMP are Kelly Farnan, Tyler Cragg at Richards, Layton & Finger;and Christopher Sorenson, Paige Stradley, Andrew Larson and Hayley Ostrin at Merchant & Gould.
Attorneys for Amneal are: Anne Shea Gaza and Samantha Wilson at Young Conaway; and Steven Maddox, Jeremy Edwards, Victor Sai, Dave Deonarine and Lianlian Wu at Procopio.
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