Anhydrous vs Monohydrate@Mometasone furoate

The District Court Of Delaware has ordered in favour of Amneal Pharmaceuticals LLC, and stated that Amneal’s product (generic Mometasone furoate nasal spray) does not infringe Merck Sharp’s US 6,127,353 which is listed in Orange book for Nasonex.


Amneal filed ANDA 207989 to produce and market a generic Mometasone furoate nasal spray; On March 20, 2015 Merck sued Amneal alleging infringement of US 6,127,353.

US ‘353 claims Mometasone furoate monohydrate and composition comprising Mometasone furoate monohydrate.

Amneal’s ANDA contains MFA (Anhydrous Mometasone furoate) as the active pharmaceutical ingredient, wherein Merck contends that the MFA in Amneal’s product will eventually convert to MFM (Mometasone furoate monohydrate). MFA and MFM are polymorphs. MFM differs from MFA in that every molecule of MFM is associated with a molecule of water, whereas no water is present in the crystal lattice structure of MFA.

Amneal produced several samples of finished product form containing MFA and produced samples of its ANDA product to Merck (Batch 16001 Day 1 samples).

Merck’s expert, Dr. Matzger conducted a thermodynamic stability test “to establish the thermodynamic stability of the monohydrate relative to the anhydrous form.”

He added an amount of MFM equal to the amount of MFA in one of the sample bottles from the Exhibit Batches and subjected the bottle to vigorous shaking at 500 RPM. After 27 days, all of the MFA had converted to MFM.

He explained that shaking “increase[s] mass transport” to help the conversion from the “less stable form to the more stable form” and “break up the viscosity” of the suspension.

Dr. Matzger concluded that “the monohydrate is the more stable form in the environment of Amneal’s formulation.” He testified that the study established that “conversion will occur,” but not “when it will occur.” He further explained that he “intentionally added [MFM] so that the conversion could take place with both forms present, and he wouldn’t know if [MFM] would become present or when it would become present if he hadn’t added it;” a person of skill in the art would “need to know all of those things to say what the rate would be in the proposed ANDA product.”

Merck’s expert Dr. Bernhardt Trout stated that it is “very difficult to make predictions” on how mixing would affect a specific system, and “to verify in a given sample whether there was conversion, it needs to be tested empirically.

Consideration of Raman Spectroscopy to identify the presence of MFM in Amneal’s product:
Raman spectroscopy is a vibrational spectroscopy technique, which looks at the way a molecule vibrates in a crystal.

IR when performed MFM has a characteristic peak around 1709 cm-1, MFA has a characteristic peak at 1725 cm-1, and the two polymorphs share a peak in the range of 1640-1680 cm-1

Dr. Matzger tested seven slides prepared from one bottle of Batch 16001 Day 1 and the obtained spectra indicates the presence of both MFM and MFA in the said sample. Dr. Matzger testified that he could not see any other characteristic peaks for MFM “because of the signal to noise limitation.”

Amneal’s expert, Dr. Brian Marquardt disagree with Dr. Matzger conclusion about the presence of MFM in Batch 16001 Day 1, and analyzed the Dr. Matzger spectra and opined that a “shoulder peak” indicative of MFA “could be easily misinterpreted … as a peak in that space and be misrepresented as MFM”. He further explained that the spectra show that “this is primarily the MFA form, which is indicated by the secondary doublet and the primary peaks … , which are indicative of both forms and opined that Dr. Matzger misinterpreted the data as MFM.” He concluded that MFM was not present.

According to Dr. Matzger a single peak is sufficient to identify MFM in the ANDA product. As per Dr. Marquardt three peaks are generally used to identify a polymorph in an unknown sample. The court concluded (based on expert testimony) that at least three peaks on a spectra must be used to identify material based on accepted practices.

Merck offers Dr. Matzger’s testing of Batch 16001 Day 1 as persuasive evidence of MFM in Amneal’s ANDA product. Merck criticizes Dr. Marquardt’s testing, arguing that such testing is insufficient to prove a negative – that MFM is not present in the ANDA product.

After the above representation’s of both the parties the court concluded that Dr. Matzger’s testimony and Merck’s related arguments are self-serving, i.e., essentially arguing that Dr. Matzger’s testing is “more and better,” therefore, only his opinion should be believed. The court is not so convinced, and finds Dr. Marquardt’s testimony at least as consistent and credible. Weighing the evidence at bar (lack of MFM in the 16001 Batch Day 1 ), the court concludes that Merck has not carried its burden to prove, by a preponderance of the evidence, that MFM is present in Amneal’s ANDA product during its two-year shelf life.