DCT
1:25-cv-01343
Grunenthal GmbH v. MSN Laboratories Pvt Ltd
Key Events
Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Grünenthal GmbH (Germany)
- Defendant: MSN Laboratories Private Limited (India) and MSN Pharmaceuticals Inc. (Delaware)
- Plaintiff’s Counsel: Morris, Nichols, Arsht & Tunnell LLP; Finnegan, Henderson, Farabow, Garrett & Dunner, LLP
- Case Identification: 1:25-cv-01343, D. Del., 11/03/2025
- Venue Allegations: Venue is alleged to be proper in the District of Delaware because Defendant MSN Pharmaceuticals Inc. is a Delaware corporation, and Defendant MSN Laboratories Private Limited is an alien corporation that may be sued in any judicial district.
- Core Dispute: Plaintiff alleges that Defendants' filing of an Abbreviated New Drug Application (ANDA) to market generic extended-release tapentadol tablets constitutes an act of infringement of two patents related to methods of using tapentadol for treating neuropathic pain and for specific dosing regimens.
- Technical Context: The technology concerns tapentadol (marketed as NUCYNTA® ER), a centrally-acting opioid analgesic used for the management of severe and persistent pain, including pain associated with diabetic peripheral neuropathy.
- Key Procedural History: This action was initiated under the Hatch-Waxman Act following Defendants' submission of an ANDA with a "Paragraph IV" certification, asserting that the patents-in-suit are invalid, unenforceable, or will not be infringed by the proposed generic products. The complaint was filed within the 45-day statutory window after Plaintiff received Defendants' notice letter, triggering a potential 30-month stay of FDA approval for the generic.
Case Timeline
| Date | Event |
|---|---|
| 2007-03-12 | ’130 Patent Priority Date |
| 2007-04-23 | ’512 Patent Priority Date |
| 2013-09-17 | ’130 Patent Issue Date |
| 2022-05-31 | ’512 Patent Issue Date |
| 2025-09-19 | Plaintiff receives Defendants' Paragraph IV Notice Letter |
| 2025-11-03 | Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 8,536,130 - Use of 1-phenyl-3-dimethylamino-propane Compounds for Treating Neuropathic Pain
The Invention Explained
- Problem Addressed: The patent's background section notes a distinction between nociceptive pain (a normal response to painful stimuli) and neuropathic pain (caused by damage to nerves). It states that many substances effective for nociceptive pain are not effective for neuropathic pain, and existing treatments like gabapentin are relatively ineffective, creating a need for improved therapies. (’130 Patent, col. 2:27-36).
- The Patented Solution: The invention is the use of a specific compound, (1R,2R)-3-(3-dimethylamino-1-ethyl-2-methyl-propyl)phenol (tapentadol), for the treatment of neuropathic pain, particularly polyneuropathic and diabetic neuropathic pain. The specification asserts that this compound is "surprisingly particularly effective" for this specific indication, in contrast to its known analgesic properties for other types of pain. (’130 Patent, col. 2:50-54, col. 3:45-50).
- Technical Importance: The invention identifies a specific therapeutic application for a known compound, addressing an unmet need for effective treatments for a difficult-to-manage chronic pain condition. (’130 Patent, col. 2:32-36).
Key Claims at a Glance
The complaint does not specify which claims are asserted, alleging infringement of "one or more claims" (Compl. ¶38). Independent claim 1 is representative:
- A method of treating polyneuropathic pain in a subject suffering therefrom,
- said method comprising administering to said subject an effective polyneuropathic pain inhibiting amount of (1R,2R)-3-(3-dimethylamino-1-ethyl-2-methyl-propyl)phenol
- or a pharmaceutically acceptable salt thereof.
U.S. Patent No. 11,344,512 - Titration of Tapentadol
The Invention Explained
- Problem Addressed: The patent discloses that while tapentadol is a well-tolerated analgesic, adverse events like somnolence (drowsiness) can occur when treatment is initiated, potentially causing patients to discontinue the therapy before its full analgesic effect is realized. (’512 Patent, col. 2:7-11).
- The Patented Solution: The invention is a specific dosing regimen, or "titration method," designed to improve the tolerability of tapentadol. The method involves initiating treatment with a comparatively low dose for a defined period and then successively increasing the dose in predefined steps and intervals. (’512 Patent, col. 2:58-62). This gradual escalation is intended to allow the patient to acclimate to the drug, reducing the incidence of side effects like somnolence. (’512 Patent, col. 3:24-34).
- Technical Importance: The claimed dosing method provides a way to manage side effects, potentially improving patient compliance and the overall therapeutic success of tapentadol treatment for chronic pain. (’512 Patent, col. 2:7-11).
Key Claims at a Glance
The complaint alleges infringement of "one or more claims" (Compl. ¶55). Independent claim 1 is representative:
- A method of treating pain with a lower incidence of somnolence in a subject, comprising orally administering:
- (i) a first dose of tapentadol of 50 mg±5% or 100 mg±5% twice daily (bid) during a first administration interval of at least 1-3 days;
- (ii) a second dose of tapentadol calculated by increasing said first dose by 50 mg to 100 mg±5% or 150 mg±5% twice daily, respectively, during a second administration interval of at least 3-11 days following the first; and
- (iii) a third dose of tapentadol calculated by increasing said second dose by 50 mg to 150 mg±5% or 200 mg±5% twice daily, respectively, during a third administration interval of at least 3-14 days following the second.
III. The Accused Instrumentality
Product Identification
Defendants' proposed generic Tapentadol extended-release tablets in 50 mg, 100 mg, 150 mg, 200 mg, and 250 mg dosage strengths, for which Defendants filed ANDA No. 220864 (Compl. ¶1).
Functionality and Market Context
The accused products are alleged to be generic versions of NUCYNTA® ER, an extended-release opioid analgesic (Compl. ¶1). The complaint alleges that the products are intended for the management of severe and persistent pain, including "neuropathic pain associated with diabetic peripheral neuropathy (DPN)" (Compl. ¶26). As a generic, the product is alleged to be "pharmaceutically and therapeutically equivalent" to the brand-name drug NUCYNTA® ER (Compl. ¶36, Compl. ¶53). The infringement theory is based on the premise that the product's proposed labeling will instruct medical professionals and patients to use the drug in a manner that practices the methods claimed in the patents-in-suit (Compl. ¶45, Compl. ¶62).
No probative visual evidence provided in complaint.
IV. Analysis of Infringement Allegations
The complaint does not contain a claim chart or detailed factual allegations mapping the accused product's use to the patent claims. The infringement theory is based on inducement, alleging the defendants' proposed product label will instruct users to perform the claimed methods. The following charts summarize the plausible infringement theories.
’130 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A method of treating polyneuropathic pain in a subject suffering therefrom, | Defendants' proposed generic product, being equivalent to NUCYNTA® ER, will be indicated for, and its package insert will instruct the treatment of, "severe and persistent neuropathic pain associated with diabetic peripheral neuropathy," which is a form of polyneuropathic pain. | ¶26, ¶45 | col. 3:48-50 |
| said method comprising administering to said subject an effective polyneuropathic pain inhibiting amount of (1R,2R)-3-(3-dimethylamino-1-ethyl-2-methyl-propyl)phenol or a pharmaceutically acceptable salt thereof. | Defendants' proposed package insert will instruct healthcare providers and patients to administer the generic tapentadol hydrochloride tablets, which contain the specified active ingredient, in therapeutically effective amounts to treat the indicated conditions. | ¶1, ¶43, ¶45 | col. 2:55-58 |
’512 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A method of treating pain with a lower incidence of somnolence in a subject, said method comprising orally administering to said subject: | Defendants' proposed package insert will allegedly instruct a dosing regimen that follows the patented method to treat pain. | ¶62 | col. 2:58-62 |
| (i) a first dose of tapentadol of 50 mg±5% or 100 mg±5% twice daily (bid) during a first administration interval of at least 1-3 days; | The complaint alleges the proposed package insert will instruct users to begin treatment with a starting dose (e.g., 50 mg twice daily) for an initial period, consistent with the reference listed drug's label and falling within the claimed parameters. | ¶62 | col. 27:5-10 |
| (ii) a second dose of tapentadol calculated by increasing said first dose by 50 mg to 100 mg±5% or 150 mg±5% twice daily (bid), respectively, during a second administration interval of at least 3-11 days following said first administration interval; and | The complaint alleges the proposed package insert will instruct users to increase the dose after the initial period by a specified amount (e.g., by 50 mg) for a subsequent period, in a manner that meets the claimed dose escalation and time interval. | ¶62 | col. 27:11-18 |
| (iii) a third dose of tapentadol calculated by increasing said second dose by 50 mg to 150 mg±5% or 200 mg±5% twice daily (bid), respectively, during a third administration interval of at least 3-14 days following said second administration interval. | The complaint alleges the proposed package insert will instruct users to perform at least one further dose increase according to a schedule that falls within the parameters of the third step of the claimed titration method. | ¶62 | col. 27:19-27 |
Identified Points of Contention
- Scope Questions: For the ’130 Patent, a potential issue is whether the indication for "neuropathic pain associated with diabetic peripheral neuropathy" on the proposed label (Compl. ¶26) falls squarely within the scope of the claimed method of treating "polyneuropathic pain."
- Technical Questions: For the ’512 Patent, the central dispute will be factual: do the specific dosing, titration, and timing instructions in Defendants' proposed package insert meet every limitation of the asserted claims? The complaint does not provide the label, making this a key open question. Any deviation in the label's recommended starting dose, escalation amount, or timing between escalations could form the basis of a non-infringement defense.
V. Key Claim Terms for Construction
Term: "polyneuropathic pain" (’130 Patent, Claim 1)
- Context and Importance: The infringement case for the ’130 Patent hinges on whether the proposed label's indication for "neuropathic pain associated with diabetic peripheral neuropathy" (DPN) instructs a method of treating "polyneuropathic pain." Practitioners may focus on this term to determine if the specific indication on the label meets this claim limitation.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification explicitly and repeatedly identifies "diabetic neuropathic pain" and "diabetic peripheral neuropathic pain" as preferred embodiments of the invention, suggesting the patentee considered DPN to be a type of polyneuropathic pain. (’130 Patent, col. 2:50-54, col. 3:48-50).
- Evidence for a Narrower Interpretation: A defendant could argue that the term should be limited to the specific clinical characteristics described in the patent's examples, or that subtle distinctions exist between DPN as commonly understood and the specific condition contemplated by the inventors, potentially seeking to narrow the claim scope.
Term: "administration interval" (’512 Patent, Claim 1)
- Context and Importance: Claim 1 of the ’512 Patent recites a three-step titration method, with each step occurring during a distinct "administration interval" of a specified duration. The definition of what constitutes an "interval" and when one ends and the next begins is critical for mapping the instructions on the accused label to the claim elements.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification describes the intervals as sequential periods of dosing, where a new interval begins upon a dose increase. (’512 Patent, col. 5:26-31). This may support a view that any period of consistent dosing followed by an instructed increase constitutes a new "interval."
- Evidence for a Narrower Interpretation: The patent describes preferred embodiments in the context of structured clinical trials with fixed durations (e.g., "After 3 days the dose is increased...") (’512 Patent, col. 27:6-7). A defendant may argue that "administration interval" requires such a formally defined, fixed-duration period, which might not be reflected in a product label that provides more flexible guidance to physicians.
VI. Other Allegations
Indirect Infringement
The core of the complaint rests on allegations of induced infringement. Plaintiff alleges that Defendants know of the patents-in-suit and that by seeking approval to market their generic products with a proposed package insert, they intend to encourage and instruct healthcare providers and patients to perform the patented methods of use. (Compl. ¶44-45, Compl. ¶61-62).
Willful Infringement
The complaint does not use the term "willful." However, it establishes a basis for potential post-suit willfulness by pleading that Defendants have had "actual knowledge" of the patents since at least the date of the Paragraph IV notice letter, September 19, 2025. (Compl. ¶37, Compl. ¶54).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of definitional scope: does the indication for "neuropathic pain associated with diabetic peripheral neuropathy" on the proposed generic label directly instruct the administration of tapentadol for the treatment of "polyneuropathic pain" as that term is construed from the ’130 Patent?
- A key evidentiary question will be one of factual correspondence: do the precise dose-escalation instructions in Defendants' proposed product label—including the starting dose, the amount of each increase, and the duration of each dosing period—map onto every limitation of the multi-step titration method claimed in the ’512 Patent? The viability of the infringement claim for this patent will depend entirely on this detailed comparison.