Patent 12,605,385 Claim-Scope and US Patent Landscape for Methotrexate Liquid with PEG, Citrate Buffer (pH 6.6–7.0)
Executive summary: US Patent 12,605,385 claims a narrow but practical formulation space: liquid methotrexate free acid at 0.4–20 mg/mL (preferably 1–5 mg/mL), with PEG (2–6 mg/mL, preferably PEG 400), and a buffered aqueous system using citrate buffer (0.02–0.06 M; pH 6.6–7.0, preferably ~6.8). Dependent claims expand coverage to specific excipients (notably glycerol and certain preservative/sweetener flavor systems). The claim structure is composition-centric (not device or use method), so infringement risk turns on matching the numerical ranges and buffer identity/strength/pH.
What does US patent 12,605,385 claim for methotrexate liquid PEG and citrate buffer?
Core independent claim coverage (Claim 1)
Claim 1 defines a liquid pharmaceutical composition with mandatory elements and numerical boundaries:
- Active: methotrexate free acid
- Polymer: polyethylene glycol at 2 to 6 mg/mL
- Buffer present
- pH: 6.6 to 7.0
- Buffer strength: 0.02 to 0.06 M
Functional impact: The claim is engineered to capture formulations intended for near-neutral stability/compatibility using measured buffer capacity, not just “buffered” language.
Claim 1 numerical “touchpoints” that control infringement
For any accused formulation, the infringement question is likely to be fact- and lab-driven on:
- Does it use methotrexate free acid (not salts or prodrugs)?
- Is the PEG concentration within 2–6 mg/mL?
- Is the buffer strength within 0.02–0.06 M?
- Is the pH within 6.6–7.0?
A design-around can focus on one of these axes by moving outside the stated numeric boundaries.
How broad are the dependent claims on glycerol, PEG type, methotrexate dose, pH, and buffer strength?
Glycerol scope (Claims 2–3)
- Claim 2: further comprising glycerol
- Claim 3: glycerol at 50 to 200 mg/mL
Scope effect: These are narrower secondary ranges. A glycerol-free formulation would avoid Claims 2–3 while still potentially practicing Claim 1 if other elements match.
PEG identity limitation (Claim 4)
Scope effect: Claim 4 is narrower than Claim 1. If a formulation uses another PEG molecular weight (eg PEG 3350, PEG 2000), Claim 4 would not apply, but Claim 1 still might if PEG is within 2–6 mg/mL.
Methotrexate concentration ranges (Claims 5–6)
- Claim 5: methotrexate 0.4–20 mg/mL
- Claim 6: methotrexate 1–5 mg/mL
Scope effect: Claim 5 is broader than Claim 6. The narrower Claim 6 creates a second layer of capture for a likely “preferred” dose concentration.
Discrete pH embodiments (Claims 7–8)
- Claim 7: pH is about 6.6, 6.7, 6.8, or 6.9
- Claim 8: pH is about 6.8
Scope effect: These claims reinforce Claim 1’s pH window by capturing likely “target” pH points. If an accused product is in-range but not “about” those points, litigating “about” meaning can become central.
Buffer strength refinements (Claims 9–10)
- Claim 9: buffer strength 0.02–0.05 M
- Claim 10: buffer strength about 0.05 M
Scope effect: Claim 9 is narrower than Claim 1 (since Claim 1 goes to 0.06 M). Claim 10 pins a preferred capacity.
What formulation details are protected by claims for flavor/sweetener and preservatives?
Flavor and sweetener add-ons (Claim 11)
- Further comprising one or more flavor and sweetener
- Flavor: orange or berry
- Sweetener: sucralose
Scope effect: Claim 11 is additive. It captures products using those organoleptics, but it is not required for Claim 1. A formulation matching Claim 1 could still avoid Claim 11 by using different flavoring/sweetener systems.
Preservatives (Claim 12)
- Preservatives selected from:
- ethyl parahydroxybenzoate
- methyl parahydroxybenzoate
- sodium salt of parahydroxybenzoate (sodium salt of parahydroxybenzoate)
Scope effect: This is a defined preservative selection list. Avoidance can be achieved via different preservative systems or preservative-free formats (if feasible), but those may create other stability constraints.
How specific is the citrate buffer limitation and what does it add (Claims 13–16)?
Buffer identity: sodium citrate buffer (Claims 13–15)
- Claim 13: buffer is sodium citrate buffer
- Claim 14: sodium citrate buffer comprises:
- tri-sodium citrate
- citric acid
- water
- Claim 15: further comprising glycerol and methyl parahydroxybenzoate sodium salt, wherein buffer is sodium citrate buffer
Scope effect: Claims 13 and 14 narrow buffer identity and composition. If an accused product uses a different buffer system (phosphate, HEPES, acetate, etc), it can avoid these dependent claims, but Claim 1 may still cover if the accused product still has the requisite pH and buffer strength (and is argued to have a “buffer” generally, unless buffer identity is required by interpretation).
A combined “preferred” embodiment (Claim 16)
- Composition comprises:
- methotrexate 0.4–20 mg/mL
- PEG 2–6 mg/mL
- citrate buffer with buffer strength 0.02–0.06 M
- pH about 6.8
Scope effect: Claim 16 ties the elements together into a single more specific combination: it reduces room for argument by aligning the pH and capacity targets with Claim 1’s bounds.
How many distinct claim “coverages” exist for this patent? (A practical mapping)
Below is a coverage map showing independent vs. dependent claim layers as litigation “bins” that can be individually satisfied or designed around.
| Claim layer |
Mandatory elements |
Key ranges / identity constraints |
| Claim 1 (base) |
Methotrexate free acid + liquid + PEG + buffer |
PEG 2–6 mg/mL; pH 6.6–7.0; buffer strength 0.02–0.06 M |
| Claim 2–3 |
Add glycerol |
glycerol 50–200 mg/mL |
| Claim 4 |
PEG type |
PEG 400 |
| Claim 5–6 |
Methotrexate range |
0.4–20 mg/mL then 1–5 mg/mL |
| Claim 7–8 |
pH targets |
“about” 6.6–6.9, or about 6.8 |
| Claim 9–10 |
Buffer strength refinements |
0.02–0.05 M, or about 0.05 M |
| Claim 11 |
Organoleptics |
orange/berry flavor + sucralose |
| Claim 12 |
Preservatives |
ethyl/methyl parahydroxybenzoate, or sodium salt form |
| Claim 13–14 |
Buffer identity/composition |
sodium citrate from tri-sodium citrate + citric acid + water |
| Claim 15 |
Specific additive set |
glycerol + methyl parahydroxybenzoate sodium salt + sodium citrate |
| Claim 16 |
Combined preferred embodiment |
methotrexate 0.4–20 mg/mL + PEG 2–6 mg/mL + citrate 0.02–0.06 M + pH ~6.8 |
Net effect: the patent can capture both a “broad base composition” (Claim 1) and narrower “product-specific” variants (Claim 4, 11–15, 16).
Where does infringement exposure likely concentrate across the formulation design space?
Highest-likelihood infringement scenario
A product that matches:
- methotrexate free acid
- PEG as 2–6 mg/mL (with PEG 400 likely)
- citrate buffer with capacity 0.02–0.06 M
- pH near 6.8
- potentially glycerol and citrate components
This scenario hits Claim 1 and likely Claim 16, plus dependent claim boosters if glycerol/preservatives/flavor match.
Lower-likelihood scenario
Products that deviate on any single axis:
- use different actives (methotrexate salts or formulations not labeled/formed as “free acid”),
- use buffer systems outside the citrate matrix (or argue buffer strength outside 0.02–0.06 M),
- use PEG outside 2–6 mg/mL,
- set pH outside 6.6–7.0.
Those formulations can avoid Claim 1 entirely if the numeric boundaries are not met.
What patent landscape exists around this specific methotrexate liquid composition space in the US?
No reliable landscape can be produced from the information provided. A complete US patent landscape requires:
- the application number, assignee, publication number(s), and continuity family data for US 12,605,385, and
- cross-referenced Orange Book listings (if applicable), plus
- any co-pending continuations and related method-of-use patents.
Because those identifiers are not included in the prompt, producing a complete, accurate landscape (expiration dates, claim overlap mapping to competing products, litigation status, and “how many patents cover” counts) would require external patent record retrieval.
How should this claim set be used for freedom-to-operate screening or claim charting?
Claim chart axes for Claim 1
Any FTO or litigation claim chart should treat these as separate elements with numeric verification:
- Methotrexate free acid (active form)
- Liquid dosage form
- PEG present at 2–6 mg/mL
- Buffer present
- pH 6.6–7.0
- Buffer strength 0.02–0.06 M
Dependent claim triggers
After establishing Claim 1 match, dependent claims become “add-on” checkpoints:
- glycerol 50–200 mg/mL
- PEG 400
- methotrexate 1–5 mg/mL
- pH “about” 6.8 or 6.6–6.9
- buffer strength “about” 0.05 M
- orange/berry + sucralose
- specific parabens
- sodium citrate composition including tri-sodium citrate + citric acid
- glycerol + methyl parahydroxybenzoate sodium salt
Key Takeaways
- US 12,605,385 protects a specific methotrexate liquid formulation framework: methotrexate free acid + PEG (2–6 mg/mL) + buffered aqueous system (pH 6.6–7.0) with buffer strength 0.02–0.06 M.
- The patent is composition-range driven: infringement hinges on meeting multiple numeric parameters simultaneously.
- Dependent claims narrow to PEG 400, methotrexate 1–5 mg/mL, specific “about” pH points, buffer strength refinements, and specific excipient systems (glycerol, sodium citrate, parabens, sucralose, orange/berry flavors).
- Highest exposure is likely for products formulated around pH ~6.8 with citrate buffer capacity in the stated range and PEG concentration within 2–6 mg/mL.
FAQs
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Does US 12,605,385 require PEG 400 or does any PEG work?
Claim 1 requires polyethylene glycol within 2–6 mg/mL; PEG 400 is specifically required only for Claim 4.
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What single parameter change is most likely to avoid Claim 1?
Moving any of PEG concentration, pH, or buffer strength outside the stated ranges can avoid Claim 1 if the formulation misses at least one mandatory limitation.
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Are glycerol and sucralose required to infringe?
No. They appear in dependent claims (glycerol in Claims 2–3; sucralose and specific flavors in Claim 11). Claim 1 does not require them.
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If a formulation uses citrate buffer but not sodium citrate, does it escape dependent claims?
Claims 13–15 require sodium citrate and, in Claim 14, specific components. A non-sodium-citrate buffer can avoid those dependent claims, though Claim 1 may still apply depending on pH and buffer strength and the claim interpretation of “buffer.”
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Can an accused product that hits pH 6.8 but has buffer strength above 0.06 M still be covered?
Claim 1 caps buffer strength at 0.06 M, with additional dependent refinements below 0.05 M. Exceeding the Claim 1 cap avoids coverage of that independent claim and any dependent claim built on the same buffer-strength range.
References
- User-provided claim text for US Patent 12,605,385 (Claims 1–16).
