Contact the author: Andrew Berks
Takeda Pharm. Co. Ltd. v. Zydus Pharms. USA, Inc., No. 2013-1406 (Fed. Cir. 2/20/2014)
This Hatch-Waxman case pertains to particle size claims for the brand name drug Prevacid® SoluTab™. The product is an orally dissolving tablet (ODT) containing lansoprzaole. Only claim 1 of US6328994 is in dispute, which reads, in relevant part:
Claim 1. An orally disintegrable tablet which comprises (i) fine granules having an average particle diameter of 400 µm or less… and (ii)… having a hardness strength of about 1 to about 20 kg…
The district court construed the particle size term to be 400 µm (±10%) or less. On this construction, the Zydus product apparently infringed. In addition, Zydus’ arguments that claim 1 was invalid were dismissed.
On appeal, the Federal Circuit panel (Prost, Plager, and Chen, opinion by Prost), reversed the claim construction of the lower court. The panel was troubled by the imputation of ±10% into the particle size claim. The purpose of the particle size limitation was to avoid a feeling of roughness in the mouth, and the panel believed the specification drew a sharp line between particles of 400 µm or less that had the desired mouth feel, and larger particles that did not. Also, there was language cited in the specification pertaining to a practical size of 425 µm or less with a 5% deviation, but then the specification defined “average particle diameter” to mean median particle diameter. This confused drafting created contradictory definitions, so the panel concluded that the inventors did not intend to incorporate a 10% deviation into the particle size limitation in claim 1. Takeda also made “lexicographer” arguments, asserting that the phrase “about 400 µm or less” was recited three times in the specification. However, the panel noted that each time this recitation appeared, it was immediately followed by the statement that the particle was size was preferably 300 to 400 µm, so this argument was rejected.
Additionally, the panel noted that claim 1 issued with no language of approximation modifying the particle size, but language of approximation did appear in claim 1 pertaining to the hardness (“about 1 to about 20 kg”), so the claim drafters weren’t bashful about language of approximation. Further, in the prosecution history, there was potentially invalidating prior art pertaining to lansoprazole particle size that was overcome by relying on a clear dividing line between particles of greater and lesser than 400 µm. Accordingly, the district court claim construction was reversed, and the claim was construed as requiring particles of precisely 400 µm or less.
The Zydus product had a particle size of 412 µm, outside of the claimed range as construed by the Federal Circuit. So there is no literal infringement of claim 1. This opinion does not discuss infringement under the doctrine of equivalents, which presumably will be left to the district court on remand.
Zydus also alleged that the ‘994 patent did not meet the requirements of 35 USC §112. Zydus alleged that the patent was indefinite for not specifying a particle size measurement method. However, the specification laser diffraction, and that was good enough for the panel, so this argument was dismissed. Zydus also alleged that the written description requirement was not met, because claim 1 addressed the particle size in the finished tablet, but the specification only discussed particle size pre-tableting. The panel dismissed this argument based on evidence from Takeda’s expert that the tableting process did not affect the particle size. Zydus also alleged that the enablement requirement was not met, because the specification did not teach a skilled artisan how to measure particle size with the “coulter counter” method without undue experimentation. This too was dismissed by the panel, which agreed with the lower court that a skilled artisan would know how to measure particle size with laser diffraction or optical microscopy.
Holding: Claim 1 is valid but not infringed. Remanded to the district court.
- This is another case suggesting that particle size claims can be viable subject matter to to extend product life cycle.
- There was a drafting problem in the specification, that strongly contributed to the panel holding limiting the patentee to a narrow claim construction.
- There appeared to be an absence of teachings in the specification of methods of particle size measurement, which left the patent open to §112 attacks.
- This case emphasizes the value of language of approximation in claims reciting numerical ranges.