CMP Development, LLC v. Amnial Farms, Inc. LLC – CaroSpir® (spironolactone) | Robbins Kaplan LLP

CMP Development, LLC v. Amnial Farms, Inc.  LLC – CaroSpir® (spironolactone) |  Robbins Kaplan LLP

Case name: CMP Development, LLC v. Amnial Farms, Inc. LLCCivNo. 21-549 (MN), 2023 WL 6387792 (D. Del. Sept. 29, 2023) (Nerica, c.)

Pharmaceutical products and patents: CaroSpir® (spironolactone); US Patent No. 10,624,906 (“the 906 patents”), 10,660,907 (“ 907 patents”), 10,888,570 (“”. 570 patents”)

Nature of the case and issues raised: CaroSpir is indicated for the treatment of heart failure, high blood pressure, and edema caused by cirrhosis. The filed patent claims about 0.18% w/v to about 0.36% w/v xanthan gum. Amnial argued that he was not violated because he used tragacanth powder — not xanthan gum — as the suspending agent. After a two-day trial, the court found that CMP had not met its burden of proving violation.

Why did Amnial win? The parties agreed that Amnial did not violate the letter, as Amnial’s product did not use xanthan gum. Instead, CMP argued that Amneal’s suspending agent — tragacanth powder — violated the allowable weight percentage for xanthan gum under the principle of equivalents. Amnial did not dispute that tragacanth powder performs substantially the same function to produce the same result as xanthan gum. Instead, Amnial suspected that tragacanth powder worked in the same way as xanthan gum.

CMP argued that tragacanth powder and xanthan gum work in much the same way because Amneal’s ANDA described a study examining four suspending agents and that only tragacanth powder and xanthan gum prevented visually observable deposits. Other than this observation, CMP has not conducted any other scientific experiments to support its argument that both excipients work in substantially the same way. More specifically, the court explained that “apart from his statement and experience as a polymer scientist, (the CMP expert) provided no scientific support for the link he made between…(the) manner in which the two suspense agents worked.” Conversely, Amnial said, suspending agents don’t increase viscosity in much the same way. In particular, due to the presence of hemorrhoids, Tragacanth powder increases viscosity by a combination of swelling and polymer chain cross-linking. It has been undisputed that xanthan gum increases viscosity only by crosslinking the dissolved polymer chains. Furthermore, the amount of tragacanth powder in the ANDA product was 0.65% w/v, which is approximately twice the amount of xanthan gum mentioned in the filed patents. CMP claimed that due to the presence of hemorrhoids, only 30-40% of the tragacanth powder would actually be tragacanth, and thus the Amnial product violated the principle of equations. But the court found that there was no expert testimony or evidence to support this theory. In short, there was no evidence that the amount of tragacanth powder in Amneal’s ANDA product was equivalent to the amount of xanthan gum found in the filed patents.

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