Par Pharmaceutical Inc v. Merck Sharp & Dohme Corp

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Par Pharmaceutical, Inc. (New York)
  • Defendant: Merck Sharp & Dohme Corp. (New Jersey)
  • Plaintiff’s Counsel: The Law Office of JASON B. LATTIMORE, ESQ. LLC
• Case Identification: [Par Pharmaceutical, Inc.](https://ai-lab.exparte.com/party/par-pharmaceutical-inc) v. [Merck Sharp & Dohme Corp.](https://ai-lab.exparte.com/party/merck-sharp-and-dohme-corp), 2:19-cv-04432, D.N.J., 02/01/2019
• Venue Allegations: Venue is alleged to be proper in the District of New Jersey because the Defendant has a principal place of business in the district, conducts substantial business there, and has previously filed patent infringement suits in the district, thereby availing itself of the jurisdiction.
• Core Dispute: Plaintiff seeks a declaratory judgment that Defendant's patent covering a specific salt form of the diabetes drug sitagliptin is invalid, an action arising under the Hatch-Waxman Act following Plaintiff's application to market a generic version of Defendant's drug, Janumet XR.
• Technical Context: The technology concerns specific crystalline salt forms of a dipeptidyl peptidase-IV (DPP-IV) inhibitor, which are designed to improve the stability and manufacturing characteristics of pharmaceutical ingredients used to treat Type 2 diabetes.
• Key Procedural History: The complaint states that Plaintiff Par sent a Paragraph IV notice letter to Defendant Merck on October 22, 2012, certifying that the patent-in-suit is invalid or would not be infringed by Par's proposed generic drug. Merck did not file an infringement suit within the statutory 45-day period, which, under the Hatch-Waxman Act, provides Par the basis to file this declaratory judgment action to obtain "patent certainty" for its Abbreviated New Drug Application (ANDA).

Case Timeline

Date	Event
2003-06-24	'708 Patent Priority Date
2008-02-05	U.S. Patent No. 7,326,708 Issued
2012-10-22	Par sends Paragraph IV certification notice to Merck
2019-02-01	Complaint for Declaratory Judgment of Invalidity Filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 7,326,708 - "Phosphoric Acid Salt of a Dipeptidyl Peptidase-IV Inhibitor," Issued February 5, 2008

The Invention Explained

• Problem Addressed: The patent is directed to improving the properties of a known class of DPP-IV inhibitors used for treating Type 2 diabetes (Patent, col. 1:50-55). While the base compound was known, the patent sought to develop a specific salt form with superior characteristics for pharmaceutical manufacturing, such as improved physical and chemical stability, ease of processing, and better solubility (Patent, col. 2:4-15).
• The Patented Solution: The invention is a novel dihydrogenphosphate salt of a specific DPP-IV inhibitor compound, 4-oxo-4-[3-(trifluoromethyl)-5,6-dihydro[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl)butan-2-amine (Patent, col. 1:63-col. 2:3). A key aspect of the invention is a specific crystalline monohydrate of this salt, which possesses advantageous properties making it "particularly suitable for the manufacture of various pharmaceutical dosage forms" (Patent, Abstract; col. 2:11-16). The patent provides detailed characterization of this crystalline form through X-ray diffraction patterns and other analytical data (Patent, FIG. 1; col. 13:21-38).
• Technical Importance: Developing stable, reliable crystalline forms of an active pharmaceutical ingredient is a critical step in drug development, as it directly impacts a drug's shelf-life, bioavailability, and the consistency of manufacturing at a commercial scale.

Key Claims at a Glance

• The complaint seeks a declaration that "the claims" of the '708 patent are invalid (Compl. ¶30). Independent claim 1 is the broadest asserted claim.
• Independent Claim 1:
  • A dihydrogenphosphate salt of 4-oxo-4-[3-(trifluoromethyl)-5,6-dihydro[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl)butan-2-amine of structural formula I; or
  • a hydrate thereof.

III. The Accused Instrumentality

Product Identification

• The subject of the action is "Par's ANDA Product," identified as a generic version of Janumet XR (sitagliptin phosphate and metformin hydrochloride) extended-release tablets (Compl. ¶1, 20).

Functionality and Market Context

• Par's product is a proposed generic drug intended to be a lower-cost, bioequivalent version of Merck's branded Janumet XR (Compl. ¶1-2). The active pharmaceutical ingredient relevant to the '708 patent is sitagliptin, which is formulated as a phosphate salt. The filing of Abbreviated New Drug Application (ANDA) No. 204144 for this product, and the associated certification that the '708 patent is invalid, forms the basis of the lawsuit (Compl. ¶1).

IV. Analysis of Infringement Allegations

The complaint does not allege infringement. As a complaint for declaratory judgment of invalidity, the plaintiff (the generic applicant) is alleging that the defendant's patent is invalid. The complaint's single count for relief is for a "Declaratory Judgment Regarding Invalidity of U.S. Patent No. 7,326,708" (Compl. p. 10).

Plaintiff Par alleges that the claims of the '708 patent are invalid for failure to comply with the requirements of Title 35 of the U.S. Code, specifically citing sections 101, 102, 103, and 112 (Compl. ¶30). The complaint does not, however, provide specific factual bases for these invalidity contentions, such as identifying prior art references for its anticipation (§102) or obviousness (§103) arguments, or explaining the basis for its subject matter eligibility (§101) or definiteness/enablement (§112) challenges. The pleading presents a generalized assertion of invalidity as permitted to establish a justiciable controversy under the Hatch-Waxman Act.

No probative visual evidence provided in complaint.

V. Key Claim Terms for Construction

• The Term: "dihydrogenphosphate salt"

• Context and Importance: This term defines the specific anionic salt-former paired with the active ingredient's cation. The patentability of the claims, particularly against an obviousness challenge, may depend on whether selecting a dihydrogenphosphate salt was an inventive step rather than a routine or obvious choice for a skilled formulator. Practitioners may focus on this term to dispute whether this specific salt provided unexpected properties compared to other common pharmaceutical salts.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The term is used generally throughout the claims and specification, suggesting it could encompass any salt formed with dihydrogenphosphate, regardless of its specific crystalline or amorphous state.
  • Evidence for a Narrower Interpretation: The specification clarifies that the salt is "comprised of one molar equivalent of mono-protonated... cation and one molar equivalent of dihydrogenphosphate (biphosphate) anion," which could be argued to limit the scope to a specific 1:1 stoichiometry (Patent, col. 4:40-44).

• The Term: "crystalline monohydrate"

• Context and Importance: This term appears in dependent claim 4 and is central to the patent's disclosure of a specific, stable form of the drug substance. The validity of claims directed to this specific polymorph will depend entirely on the precise definition of this crystalline structure and whether it was novel and non-obvious.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: A party might argue the term covers any crystalline form that incorporates approximately one molecule of water per molecule of the salt.
  • Evidence for a Narrower Interpretation: The patent provides extensive and highly specific characterization data to define this term, including an X-ray powder diffraction (XRPD) pattern with characteristic peaks at specific d-spacings (e.g., 7.42, 5.48, and 3.96 angstroms), as well as specific solid-state NMR, TGA, and DSC data (Patent, col. 13:29-38; FIG. 1, 4, 5). A party would argue that the term is strictly limited to a crystalline solid exhibiting these exact physical properties.

VI. Other Allegations

The complaint does not contain allegations of indirect or willful infringement.

VII. Analyst’s Conclusion: Key Questions for the Case

This declaratory judgment action appears to be a procedural vehicle for a generic drug manufacturer to challenge the validity of a patent listed in the FDA's Orange Book. The key questions for the court will likely be:

1. A central issue will be one of patentability over the prior art: was the selection of a dihydrogenphosphate salt for the known sitagliptin compound, and the subsequent isolation of its crystalline monohydrate form, an obvious step for a person of ordinary skill in pharmaceutical formulation at the time of the invention? The case will likely turn on evidence of what properties were expected from such a salt versus what was actually achieved.

2. A second question will relate to enablement and written description under §112: does the '708 patent's specification provide sufficient detail to teach a skilled artisan how to make and use the full scope of the claimed salt and its hydrates, and does it demonstrate that the inventors were in possession of the claimed invention?

3. The procedural history itself raises a strategic question: why did Merck decline to sue within the 45-day Hatch-Waxman window in 2012, and what impact, if any, does the nearly seven-year delay between Par's notice and this suit have on the parties' litigation positions?