United States Patent 12,370,168 (Method Claims for Subcutaneous Furosemide Liquid Formulations Using Tris(hydroxymethyl)aminomethane Buffer): Scope, Claim Construction Levers, and US Patent Landscape
Executive summary. US 12,370,168 is a formulation-and-method-of-treatment patent focused on liquid, buffered furosemide (sole active) delivered subcutaneously, including via patch/pump devices. The strongest infringement hooks are (i) the coupled buffer system and concentration window for tris(hydroxymethyl)aminomethane (Tris), (ii) pH 7 to 8.5, and (iii) Tris:furosemide molar ratio thresholds. The patent also narrows commercial embodiments by specifying furosemide at ≥5 mg/mL and subcutaneous delivery via a patch device. The independent claim set is method claims, so enforceability depends on whether an accused product is used to perform the claimed treatment and meets the numeric formulation/ratio/pH limitations.
What is the claim scope of US Patent 12,370,168 for furosemide edema and heart failure treatment?
Short answer. The patent claims methods of treating edema, hypertension, or heart failure by administering a specific liquid furosemide formulation where furosemide is the only active agent and where Tris buffer concentration, pH, and Tris:furosemide molar ratio meet defined numeric thresholds. Dependent claims narrow to isosmotic formulations and to subcutaneous administration using a pump/patch device.
Independent claim 1: formulation-limited method of treatment
Claim 1 requires all of the following, in combination:
- Treatment target (indication): a patient with or exhibiting symptoms of edema, hypertension, or heart failure.
- Route/form: administration of a liquid pharmaceutical formulation.
- Sole therapeutic active: furosemide or a pharmaceutically acceptable salt, hydrate, or ester of furosemide, and furosemide is the sole therapeutically active agent in the liquid formulation.
- Dose concentration floor: furosemide amount about 5 mg/mL or greater.
- Buffer identity: a pharmaceutically acceptable buffer comprising Tris (tris(hydroxymethyl)aminomethane).
- Tris concentration window: 50 mM to 250 mM Tris.
- pH window: formulation pH about 7 to about 8.5.
- Ratio requirement: molar ratio of Tris to furosemide ≥ 2.
Practical construction levers.
- “Sole therapeutically active agent” is a high-value scoping element. A product with additional actives (for example, add-on diuretics, antihypertensives, or combination therapy where another active contributes therapeutically) may avoid the claim even if the furosemide/Tris/pH parameters match.
- The numeric parameters are likely the primary infringement battleground: Tris concentration, pH, and molar ratio.
- “About” introduces tolerance. In litigation, this typically becomes a fact question linked to examples and measurement variability.
Dependent claim 2: isosmotic
Claim 2 narrows claim 1 by requiring the liquid formulation be isosmotic. This is a second-layer scoping element that can be used to differentiate between formulations that meet pH/Tris/furosemide constraints but have different tonicity.
Dependent claims 3–5: narrower Tris, narrower pH, narrower furosemide range
- Claim 3: Tris concentration 50–150 mM.
- Claim 4: pH 7.2–8.0.
- Claim 5: furosemide 6–10 mg/mL.
These dependent claims define tighter “design zones” that could be used as evidence of specificity and also as fallback positions in claim charting.
Dependent claims 6–8: subcutaneous administration using pump/patch
- Claim 6: administration is subcutaneous.
- Claim 7: subcutaneous administration using a pump device.
- Claim 8: the pump device is a patch device.
These claims narrow the method context to a specific delivery system. For a patch delivery product, these dependent claims can be strong if the formulation parameters match.
How broad is the second independent claim (claim 9) vs claim 1?
Short answer. Claim 9 is still a method for the same indications but tightens several parameters (Tris 50–100 mM, pH 7.2–8, Tris:furosemide ≥1.5) and adds a specific dispensation context: subcutaneous patch device.
Claim 9 requires:
- Indications: edema, hypertension, or heart failure symptoms.
- Administration mechanics: subcutaneous using a patch device to dispense the liquid formulation.
- Sole active: furosemide (or acceptable salt/hydrate/ester) as the sole therapeutically active agent.
- Furosemide concentration: greater than about 5 mg/mL (a “>” rather than “≥” threshold).
- Tris concentration: 50–100 mM.
- Ratio: Tris:furosemide ≥1.5.
- pH: 7.2–8.
Key scope difference vs claim 1.
- Claim 1 has a higher ratio threshold (≥2) and a broader Tris range up to 250 mM.
- Claim 9 accepts a lower ratio threshold (≥1.5) but narrows Tris concentration and pH to tighter subranges and locks the delivery context to a patch device.
- In practice, claim 1 can cover more formulation variants, while claim 9 can cover fewer formulation variants but is narrower on delivery method, which can be decisive for product differentiation.
What formulation parameters drive infringement risk for US 12,370,168?
Short answer. The infringement analysis will usually reduce to whether the accused product’s liquid formulation meets the numeric constraints simultaneously, and whether the administration method matches the claimed delivery context.
Core numeric constraints
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Furosemide concentration
- Claim 1: ≥ about 5 mg/mL
- Claim 9: > about 5 mg/mL
- Dependent claim 5: 6–10 mg/mL
-
Tris concentration
- Claim 1: 50–250 mM
- Claim 3: 50–150 mM
- Claim 9: 50–100 mM
-
pH
- Claim 1: 7.0–8.5
- Claim 4: 7.2–8.0
- Claim 9: 7.2–8.0
-
Tris:furosemide molar ratio
- Claim 1: ≥2
- Claim 9: ≥1.5
Formulation identity constraints
- Buffer must include Tris (Tris is the designated buffer component).
- Buffer also must be “pharmaceutically acceptable.” This typically allows additional excipients, but not other therapeutically active agents.
Therapeutic active agent constraint
- Furosemide is the sole therapeutically active agent.
- This is the most powerful non-numeric avoidance strategy if competitors use combination diuretics or co-formulated actives.
How do patch device and pump device limitations affect design-around and enforceability?
Short answer. The method claims are not limited to a device for claim 1, but dependent claims 6–8 are. Separate product versions can be designed to operate outside those dependent claim contexts, while still potentially implicating claim 1.
Device-dependent narrowing
- Claim 6: subcutaneous route
- Claim 7: pump device
- Claim 8: patch device
Implications for enforcement.
- If an accused product administers furosemide subcutaneously but uses a different device form factor (for example, syringe-based infusion or non-patch injector), it may avoid claims 7–8 while still potentially infringing claim 1 (if claim 1 is met).
- If an accused product is intended for intravascular, oral, or other routes, it likely avoids claim 1 absent a scenario where it is “administering to a patient” subcutaneously or otherwise within the claimed method framework. Claim 1 itself does not specify subcutaneous, but the formulation is for treatment and “administering to a patient a liquid pharmaceutical formulation” is broad on route. Device and route become critical mainly in dependent claims.
How strong is the patent estate based on claim structure alone?
Short answer. The estate strength is driven by claim specificity to a particular buffered liquid furosemide composition (Tris identity plus concentration plus pH plus ratio) and by the method coupling to clinical indications.
Strength indicators
- High specificity of formulation. Numeric constraints on Tris concentration, pH, and molar ratio reduce the chance that prior art or competitors “accidentally” fall within scope.
- Sole active limitation. Excludes many combination products and can simplify claim charts.
- Delivery system capture through dependent claims. Patch-based subcutaneous delivery is directly covered.
Potential weakness indicators
- If the underlying priority dates align with known buffered furosemide liquid formulations, novelty/obviousness could be contested. However, the enforcement scope remains narrow due to numeric constraints.
- Method claims can require proof of administration “as claimed.” In the US, litigation often focuses on product labeling, prescribing behavior, and intended use to show the method is practiced by or attributable to the defendant.
What is the likely US regulatory and Orange Book posture for furosemide liquid patch products?
Short answer. The claim set is consistent with a formulation/delivery-system patent that would typically be listed in the FDA Orange Book for an approved “furosemide” product, if the product is coded as an NDA/505(b)(1) drug. For generic applicants, this creates a pathway for Paragraph IV certifications against the listed patents tied to the drug product.
Operational landscape for furosemide delivery.
- If a furosemide product is approved specifically as a liquid formulation intended for subcutaneous administration (including patch dispensers), patent listing is likely.
- Generic competition for “method-of-use” patents depends on whether the generic label or labeling carve-outs practice the claimed method and whether the generic product’s formulation matches the claimed numeric parameters.
(Orange Book and FDA database status is not provided in the prompt; therefore, this analysis focuses on claim-structure implications rather than listing verification.)
Which competitor generics or biosimilar-like risks apply to a furosemide buffered formulation patent?
Short answer. This is not a biologic, so “biosimilar” risk is not applicable. The competitive risk is conventional generic and 505(j) type products, and 505(b)(2) formulations that could differ in excipients, buffer type, pH, or Tris:furosemide ratio.
Generic entry risks
A generic (or 505(b)(2) follow-on) is most likely to avoid the patent by at least one of these:
- Using a different buffer system (no Tris or Tris below required concentration).
- Using a Tris:furosemide molar ratio below the thresholds.
- Moving pH outside the allowed windows.
- Formulating furosemide below the concentration floors.
- Including another therapeutically active agent (less common for generic furosemide, but possible in combination products).
- Avoiding subcutaneous patch device practice to dodge dependent claims (but claim 1 may still apply since it is not route-limited in your text).
Design-around focus
The most direct design-around is to keep the product a liquid furosemide formulation but move at least one of:
- Tris identity or concentration
- pH
- Tris:furosemide molar ratio
What do the claims imply about manufacturing and quality attributes?
Short answer. The patent ties scope to measurable physicochemical parameters. Manufacturing controls that influence pH, buffer concentration, and nominal drug concentration can determine infringement.
Quality attributes tied to infringement
- pH control at 7.0–8.5 (or 7.2–8.0 depending on dependent/independent scope)
- Buffer concentration control at 50–250 mM (or 50–100 mM depending on claim 9)
- Tris-to-furosemide ratio tracking through formulation calculations and assay variability
- Furosemide assay at ≥5 mg/mL thresholds and within 6–10 mg/mL in claim 5
US patent landscape mapping: what matters around US 12,370,168 despite not listing other patents here?
Short answer. Without enumerating other patent numbers in the prompt, the landscape analysis must be expressed by claim “landscape categories” likely surrounding such a patent: (i) furosemide formulation patents, (ii) Tris-buffered pharmaceutical formulation patents, (iii) subcutaneous delivery and patch/pump device patents, and (iv) method-of-use patents for edema/heart failure/diuretic therapy.
Landscape categories and how they intersect
-
Furosemide formulation patents
- Likely focus on solubility, stability, pH, tonicity, and suitable excipients for liquid delivery.
- Your patent stands out by specifying Tris and numeric Tris/pH/ratio targets.
-
Buffer system patents
- Tris as a buffer is common in pharmaceutical formulations, but the claimed molar ratio and concentration window are the distinctive elements.
-
Subcutaneous infusion/patch device patents
- Capture of pump/patch features suggests overlap with device IP. If a competitor uses a different dispenser mechanism, they may avoid device-dependent claims.
-
Method-of-treatment patents
- The indication language (edema, hypertension, heart failure) is broad. The differentiating factor is the administered formulation parameters.
Claim chart structure: how to test an accused product against US 12,370,168
Short answer. A litigation-grade claim chart should check each limitation in sequence, with measurement evidence for each numeric parameter.
Claim 1 chart (checklist)
- Indication: edema, hypertension, or heart failure symptoms?
- Administration: liquid formulation administered to a patient?
- Active agent: furosemide is sole therapeutically active agent?
- Concentration: furosemide ≥5 mg/mL (about)?
- Buffer: includes Tris?
- Tris concentration: 50–250 mM?
- pH: 7–8.5 (about)?
- Molar ratio: Tris:furosemide ≥2?
Claim 9 chart (checklist)
- Indication: same?
- Route/device: subcutaneous via patch device dispensing?
- Active agent: furosemide is sole active?
- Furosemide concentration: >5 mg/mL (about)?
- Tris concentration: 50–100 mM?
- Ratio: ≥1.5?
- pH: 7.2–8?
Dependent claims attach to the above if their added parameters also match.
Key Takeaways
- US 12,370,168 is a formulation-and-method patent centered on liquid furosemide with Tris buffer plus strict pH and Tris-to-furosemide molar ratio requirements.
- The strongest infringement risk is tied to numeric formulation parameters (Tris concentration, pH, and molar ratio) and the sole-active limitation.
- Patch and pump limitations are mainly captured in dependent claims (6–8), while claim 1 can apply beyond a specific device context.
- Design-arounds are straightforward in principle: change the buffer system, shift pH, adjust Tris concentration and molar ratio, or move furosemide concentration below the claimed thresholds; combination therapeutics can also avoid “sole active.”
FAQs
- Can a competitor infringe US 12,370,168 if it uses a different buffer than Tris while keeping the same pH and furosemide concentration?
- Does “about 5 mg/mL” in claim 1 allow meaningful product tolerance, and how is it typically evaluated in infringement analyses?
- If a product is subcutaneous but not delivered by a patch device, which claims of US 12,370,168 remain most exposed?
- How do the dependent claim ranges (Tris 50–150 mM; pH 7.2–8.0; furosemide 6–10 mg/mL) affect fallback positions in litigation?
- What labeling or intended-use evidence is most relevant to proving infringement of method-of-treatment claims tied to heart failure and edema?
References
No external sources were cited because the prompt did not include bibliographic details (filing dates, priority claims, assignees, prosecution history, Orange Book listing, related patents, or litigation records) needed to support numbered APA citations.
