Mallinckrodt Pharma Ireland Ltd v. Baxter Healthcare Corp

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Mallinckrodt Pharmaceuticals Ireland Limited (Ireland)
  • Defendant: Baxter Healthcare Corporation (Delaware)
  • Plaintiff’s Counsel: Richards, Layton & Finger, P.A.
• Case Identification: 1:24-cv-01034, D. Del., 09/13/2024
• Venue Allegations: Venue is alleged to be proper in the District of Delaware because Defendant is a Delaware corporation and therefore resides in the judicial district.
• Core Dispute: Plaintiff alleges that Defendant’s Abbreviated New Drug Application (ANDA) for a generic version of Plaintiff's Ofirmev® product infringes four patents related to methods of administering reduced-dose intravenous acetaminophen for pain and fever.
• Technical Context: The technology concerns specific dosing regimens for intravenous acetaminophen, a widely used non-opioid analgesic in postoperative and hospital settings.
• Key Procedural History: The asserted patents and Baxter's ANDA were the subject of a previous lawsuit between the parties in 2020, which resulted in a negotiated settlement and license agreement. Plaintiff alleges that the current dispute arises from a supplement to Baxter's ANDA for a product formulation that is not covered by the prior license agreement. All four asserted patents have been previously litigated against other parties in the District of Delaware.

Case Timeline

Date	Event
2007-11-13	Earliest Priority Date for all Asserted Patents
2016-07-26	U.S. Patent No. 9,399,012 (’012) Issued
2017-04-04	U.S. Patent No. 9,610,265 (’265) Issued
2018-06-05	U.S. Patent No. 9,987,238 (’238) Issued
2019-08-20	U.S. Patent No. 10,383,834 (’834) Issued
2020-02-19	Baxter's Previous Notice Letter to Mallinckrodt
2020-03-27	Prior Infringement Suit Filed by Mallinckrodt vs. Baxter
2020-04-30	Prior Lawsuit Resolved via Settlement/License Agreement
2024-07-31	Baxter Sends Current Notice Letter to Mallinckrodt
2024-08-01	Mallinckrodt Receives Current Notice Letter
2024-09-13	Complaint Filed

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

U.S. Patent No. 9,399,012 - "Reduced Dose Intravenous Acetaminophen", issued July 26, 2016

The Invention Explained

• Problem Addressed: The patent describes a clinical problem where the standard 1000 mg intravenous (IV) dose of acetaminophen provides pain relief for a duration shorter than the minimum six-hour dosing interval, which is limited by daily toxicity caps. This mismatch creates a "gap in coverage" for patients needing consistent pain management (’012 Patent, col. 3:20-43).
• The Patented Solution: The invention proposes a method of administering a reduced dose of IV acetaminophen (between 550 mg and 800 mg) at more frequent intervals (every 3 to 5 hours). This approach is designed to provide more stable plasma concentrations and better overall pain relief without exceeding the maximum recommended daily dose of 4 grams (’012 Patent, col. 3:44-57).
• Technical Importance: This dosing strategy provides physicians with greater flexibility to tailor pain management to individual patient needs and allows for smoother transitions from IV to oral acetaminophen products (’012 Patent, col. 3:50-59).

Key Claims at a Glance

• The complaint asserts the patent generally, with Independent Claim 1 being representative.
• Independent Claim 1: A method for treating pain or fever, with key elements including:
  • Administering to a human subject weighing at least 50 kg an IV pharmaceutical composition comprising about 550 mg to about 800 mg of acetaminophen.
  • Repeating the administration at least once at an interval of about 3 to about 5 hours.
• The complaint does not explicitly reserve the right to assert dependent claims, though this is standard practice.

U.S. Patent No. 9,610,265 - "Reduced Dose Intravenous Acetaminophen", issued April 4, 2017

The Invention Explained

• Problem Addressed: As a continuation of the '012 patent, the ’265 Patent addresses the same clinical challenge: the side effects of opioids and NSAIDs, and the "gap in coverage" resulting from the standard 1000 mg IV acetaminophen dosing regimen (’265 Patent, col. 1:19-41, col. 3:23-46).
• The Patented Solution: The invention claims a method of treating pain by combining a reduced dose of IV acetaminophen with an opioid analgesic. This combination therapy leverages the reduced acetaminophen dose to manage pain, potentially reducing the required amount of opioids and their associated side effects (’265 Patent, col. 2:13-18; col. 12:41-44).
• Technical Importance: This approach facilitates multimodal analgesia, a standard of care in pain management, by providing a specific, patented method for combining a reduced-dose IV acetaminophen with opioids to enhance pain relief (’265 Patent, col. 12:41-61).

Key Claims at a Glance

• The complaint asserts the patent generally, with Independent Claim 1 being representative.
• Independent Claim 1: A method of treating pain, with key elements including:
  • Co-administering to a human subject weighing at least 50 kg a first pharmaceutical composition comprising about 500 mg to about 750 mg of acetaminophen administered intravenously.
  • Co-administering a second pharmaceutical composition comprising an opioid analgesic.
• The complaint does not explicitly reserve the right to assert dependent claims.

U.S. Patent No. 9,987,238 ('238 Patent) - "Reduced Dose Intravenous Acetaminophen"

• Patent Identification: U.S. Patent No. 9,987,238, "Reduced Dose Intravenous Acetaminophen", issued June 5, 2018.
• Technology Synopsis: This patent, part of the same family, claims methods for treating pain by administering a reduced IV dose of acetaminophen (500 mg to 750 mg). The method specifies repeating the administration every four hours, a dosing frequency intended to optimize pain relief while staying within safety limits (’238 Patent, col. 3:23-52).
• Asserted Claims: The complaint asserts the patent generally; Independent Claim 1 is representative, claiming a method of treating pain by administering about 500-750 mg of acetaminophen and repeating administration every four hours.
• Accused Features: The complaint alleges that the proposed labeling for Baxter's 650 mg ANDA product will instruct or encourage administration in a manner that infringes the claimed method (Compl. ¶¶22, 47).

U.S. Patent No. 10,383,834 ('834 Patent) - "Reduced Dose Intravenous Acetaminophen"

• Patent Identification: U.S. Patent No. 10,383,834, "Reduced Dose Intravenous Acetaminophen", issued August 20, 2019.
• Technology Synopsis: This patent claims a more specific method of treating pain by administering an IV formulation of about 650 mg of acetaminophen and repeating the dose every four hours. This regimen is designed to provide effective analgesia while ensuring the total daily dose remains below 4000 mg (’834 Patent, col. 23:12-21).
• Asserted Claims: The complaint asserts the patent generally; Independent Claim 1 is representative, claiming a method of treating pain by administering about 650 mg of acetaminophen and repeating administration every four hours.
• Accused Features: The complaint alleges that Baxter's specific 650 mg/65 mL ANDA product, when used as instructed by its proposed label, will directly infringe the claimed method (Compl. ¶¶22, 55).

III. The Accused Instrumentality

• Product Identification: The accused instrumentality is Defendant’s proposed generic "Acetaminophen Injection, 10 mg/mL" product, which is the subject of Abbreviated New Drug Application (ANDA) No. 214331 (Compl. ¶6). The specific product at issue is a formulation with a strength of 650 mg/65 mL (Compl. ¶22).
• Functionality and Market Context: The product is a generic version of Plaintiff’s branded Ofirmev® and is intended for intravenous administration for the management of pain and the reduction of fever (Compl. ¶¶6, 17). The infringement alleged is a technical act of infringement under 35 U.S.C. § 271(e)(2)(A), which arises from the submission of an ANDA seeking FDA approval to market a generic drug prior to the expiration of patents listed in the FDA's Orange Book (Compl. ¶¶18, 29). The complaint alleges that the commercial manufacture and sale of this product would cause irreparable harm to the Plaintiff (Compl. ¶35). No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint does not provide claim charts or detailed infringement contentions, as is common in initial ANDA complaints. The infringement theory is based on the allegation that the proposed labeling for Baxter’s ANDA product will instruct administration in a manner that falls within the scope of the asserted method claims.

’012 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A method for the treatment of pain or fever in an adult human or an adolescent human subject weighing at least 50 kg	Baxter's ANDA product is a generic equivalent of Ofirmev®, which is indicated for the management of pain and reduction of fever in adult and pediatric patients 2 years and older.	¶¶6, 17, 31	col. 6:1-5
comprising administering to the subject... a therapeutically effective amount of a pharmaceutical composition comprising about 550 mg to about 800 mg of acetaminophen	Baxter's ANDA product is specifically formulated to provide a dose of 650 mg of acetaminophen per 65 mL vial, which falls within the claimed range.	¶22	col. 6:40-56
and repeating said administration at least once at an interval of about 3 to about 5 hours	The complaint alleges that use of Baxter's product "in accordance with its proposed labeling" will infringe. It is implied that the label will instruct a dosing interval that falls within the claimed range, which is more frequent than the standard 6-hour interval for 1000 mg doses.	¶¶29, 31	col. 11:13-24

’265 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A method of treating pain in a human subject weighing at least 50 kg	Baxter's ANDA product is a generic version of Ofirmev®, which is indicated for pain management in adults.	¶¶6, 17, 39	col. 1:1-2
comprising: co-administering to the subject a therapeutically effective amount of a first pharmaceutical composition comprising about 500 mg to about 750 mg of acetaminophen	Baxter's ANDA product is specifically formulated to provide a dose of 650 mg of acetaminophen, which falls within the claimed range.	¶22	col. 23:60-63
and a therapeutically effective amount a second pharmaceutical composition comprising an opioid analgesic	The complaint alleges that use of Baxter's product "in accordance with its proposed labeling" will infringe. Plaintiff's branded Ofirmev® is indicated for use with adjunctive opioid analgesics, and it is implied that Baxter's proposed label for its generic equivalent will contain a similar instruction for co-administration.	¶¶17, 39	col. 12:41-44

• Identified Points of Contention:
  • Contractual Scope: A primary issue will be whether the prior license agreement from the 2020 settlement covers Baxter's current ANDA supplement for a 650 mg/65 mL product. The complaint asserts it does not (Compl. ¶22), but this will likely be a significant point of dispute concerning contract interpretation and potential estoppel.
  • Evidentiary Questions: The complaint does not include Baxter's proposed product label. A central question for the court will be whether the instructions for use in that label, once produced in discovery, actually direct a method of administration that meets all limitations of the asserted claims, particularly the dosing intervals and co-administration with opioids.

V. Key Claim Terms for Construction

• The Term: "about" (e.g., "about 650 mg," "about 3 to about 5 hours")

• Context and Importance: The definition of "about" is critical for determining the literal scope of the claimed dosage amounts and time intervals. A narrow construction may limit the claims to the precise numbers disclosed, whereas a broader construction could capture a wider range of dosing regimens. Practitioners may focus on this term because the accused product's specific 650 mg dose is explicitly claimed in the later '834 patent, but falls within the "about" ranges of the earlier patents.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The specification frequently uses broad ranges and examples, such as describing compositions comprising "about 500 mgs to about 1 gram" and listing numerous potential dosage amounts, suggesting the numbers are not intended as rigid endpoints (’012 Patent, col. 2:52-53; col. 6:40-56).
  • Evidence for a Narrower Interpretation: The specification also describes specific clinical trials and examples, such as a study using a "650 mg IV dose" (’012 Patent, col. 12:5-7, Example 3). A party could argue these specific embodiments should cabin the meaning of "about" to values very close to those explicitly tested and disclosed.

• The Term: "co-administering" (’265 Patent, Claim 1)

• Context and Importance: This term's construction will define the required temporal and therapeutic relationship between the IV acetaminophen and the opioid analgesic. The dispute will center on whether the term requires simultaneous delivery or allows for sequential administration as part of a broader pain management plan.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The patent specification discusses combination therapies where components "may be administered at the same time or sequentially in any order at different points in time," as long as the desired therapeutic effect is achieved (’265 Patent, col. 6:49-55).
  • Evidence for a Narrower Interpretation: The same section also uses the term "concurrent administration" and states that if not administered at the same time, components "should be administered sufficiently closely in time," preferably "within the same hour." A party could argue this language supports a more restrictive definition requiring close temporal proximity (’265 Patent, col. 6:55-62).

VI. Other Allegations

• Indirect Infringement: The complaint alleges that if Baxter's ANDA is approved, its commercial activities will induce and/or contribute to infringement by healthcare professionals (Compl. ¶¶31, 39, 47, 55). The basis for this allegation is that Baxter's proposed product labeling will instruct medical personnel to administer the drug using the patented methods.
• Willful Infringement: While the complaint does not use the word "willful," it repeatedly alleges that Baxter was "aware of the existence" of each asserted patent and aware that its ANDA submission constituted an act of infringement (e.g., Compl. ¶¶33, 34). This awareness is predicated on the patents' listing in the Orange Book and, critically, the parties' prior litigation over the same patents and ANDA. These allegations establish a basis for a potential future claim of willful infringement.

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

• A threshold issue will be one of contractual estoppel: Does the 2020 settlement and license agreement between the parties bar the present lawsuit, or does Baxter's ANDA supplement for a 650 mg/65 mL product constitute a new, unlicensed act that falls outside the scope of the prior agreement?
• A key evidentiary question will be one of induced infringement: As the complaint does not contain the accused product label, the case will turn on whether Baxter's proposed instructions for use direct clinicians to administer the 650 mg dose at a frequency and in a manner (e.g., with adjunctive opioids) that reads on the specific method limitations of the asserted patents.
• A central question of claim scope will be the interpretation of the term "about." The court's construction will determine whether the earlier patents, which claim broader ranges, are infringed by a product that corresponds exactly to the dosage recited in a later-issued patent in the same family.