Shire Development LLC v. Watson Pharma., Inc.

Finding expert's testing and testimony credible, court finds ANDA product infringes melting point claim limitations and rejects lack of written description and non-enablement invalidity arguments.

July 15, 2013

Robins Kaplan GENERICally Speaking: A Hatch-Waxman Litigation Bulletin

Case Name: Shire Development LLC v. Watson Pharma., Inc., Case No. 12-cv-60862, 2013 U.S. Dist. LEXIS 66335 (S.D. Fla. May 9, 2013) (Middlebrooks, J.)

Drug Product and Patent(s)-in-Suit:Lialda® (mesalamine); U.S. Patent No. 6,773,720 (“the ’720 patent”)

Nature of the Case and Issue(s) Presented: The issues presented in the case concern infringement, both literal and under the doctrine of equivalents, and whether the asserted claims are invalid for lack of written description or non-enablement.

One claim element requires magnesium stearate to have a “melting point[] below 90° C.” To prove that magnesium stearate has melting points below 90° C, Shire’s expert tested the magnesium stearate found in Watson’s ANDA Product and found that the magnesium stearate Watson uses is a hydrate of magnesium stearate (also known as “magnesium stearate dihydrate”). Plaintiffs also provided the testimony of another expert who relied on references to conclude that the magnesium stearate used in the Watson ANDA Product has a melting point below 90° C in addition to the web site of Watson’s magnesium stearate supplier, Covidien/Mallinckrodt, which reports magnesium stearate to have a melting point below 90° C.

More particularly, Shire’s expert’s tests demonstrated two melting points: one around 80° C, another around 125° C. The second endothermic peak is a melt of the anhydrous form of magnesium stearate. Shire’s expert claims that the first peak is the simultaneous dehydration and melt of magnesium stearate dihydrate, and therefore, the magnesium stearate used in Watson’s ANDA product has a melting point below 90° C. Watson’s expert, on the other hand, claimed that the first peak is only the dehydration of magnesium stearate, and thus magnesium stearate “melts” at the second melting point, when the temperature is above 90° C. Watson’s expert relied also on present-day references that show a melting point for magnesium stearate greater than 90° C, like the Handbook of Pharmaceutical Excipients.

But even if the melting point of magnesium stearate was greater than 90 C, Shire argued that Watson’s ANDA product infringed under the doctrine of equivalents because it is equivalent to stearic acid. Shire argued that magnesium stearate and stearic acid are related compounds and perform the same function of slowing drug release.

As for invalidity, Watson argued that if its ANDA product is found to infringe the ’720 patent, then the patent is invalid for lack of written description and enablement because the Watson ANDA product is not adequately described in or enabled by the ’720 patent. Further, Watson argued that if the claims were construed broad enough to encompass the Watson ANDA product, then the ’720 patent’s written description is inadequate because it does not teach a “mixed matrix” composition.

The Court found the asserted patent infringed and valid.

Why Shire Prevailed: The court held that Watson’s ANDA product infringed the asserted claims literally and under the doctrine of equivalents. The court found Shire’s expert credible and the tests results demonstrated that the sharp melting point at 80° C was of crystalline magnesium stearate and could not have resulted from the dehydration of magnesium stearate. The second melting point peak shows a very sharp peak that is the melt from a pure, high quality crystal. This is important because it demonstrates what happened during the first peak. Such a high quality crystal needs to be produced from a liquid, and since that liquid would have to be created during the first melting point peak, the crystalline magnesium stearate dihydrate must turn from solid to liquid during the first peak. The court acknowledged the differences in the literature regarding the melting point, but found that the evidence presented by Shire was sufficient to show that the melting point was below 90° C.

Likewise, the court found persuasive Shire’s expert’s testimony that magnesium stearate in Watson’s generic drug performed substantially the same function, in substantially the same way, to achieve substantially the same result as the stearic acid described in the ’720 patent. Specifically, magnesium stearate is equivalent to stearic acid, which is lipophilic and a hydrogenated fatty acid that has a melting point below 90° C. Shire’s experts testified not only that magnesium stearate and stearic acid are “related compounds,” but also that they both are known to perform the function of slowing drug release by virtue of their lipophilic nature. One of those experts further testified that using stearic acid in the ’720 patent and using magnesium stearate in the Watson ANDA product has the same result: it would control the release of mesalamine.

Finally, the court rejected Watson’s invalidity arguments. Watson’s expert testified that “[t]he example of the ’720 patent and the specifications will allow you to make a product that would fit [Claim 1].” He also testified as such with regard to Claim 3. Therefore, Watson did not meet its burden establishing a violation of 35 U.S.C. § 112.

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