What does US Drug Patent 11,285,098 cover, and how broad are its claims?
US Drug Patent 11,285,098 claims and landscapes break down into a narrow, formulation-level hydrogel space: aqueous, pH 3 to 5 hydrogels that are devoid of active pharmaceutical ingredient, built from (i) polyhydric alcohol, (ii) a viscosity increasing agent, and (iii) a specified menu of buffers and/or buffering agents, optionally with preservatives and neutralizing agents.
From a scope standpoint, the claims function like a “template” patent: they control composition parameters and component choices more than they control any one drug or method of use. The practical enforcement surface is therefore formulation replication rather than therapeutic claims.
What are the independent claim pillars?
Claim 1: what is locked down?
Claim 1 is the core independent claim. It recites:
- Dosage form / physical form: “composition in the form of a hydrogel”
- Target pH window: “pH in a range of 3 to 5”
- Core polymer/solvent system:
- at least one polyhydric alcohol, about 1% to about 30% by weight
- at least one viscosity increasing agent, about 0.1% to about 5% by weight
- water about 70% to about 99% by weight
- Buffering system (restricted selection):
- at least one buffer and/or buffering agent that “consists essentially of” a long list including, among others:
- acetic acid / acetate buffer
- hydrochloric acid
- citrate buffer / citric acid
- citro-phosphate buffer
- phosphate buffer
- lactic acid / lactic acid buffer
- tartaric acid buffer
- malic acid / malic acid buffer
- glycine/HCl buffer
- saline buffer; PBS; TBS; Tris-HCl; NaCl
- Tween buffered saline (TNT)
- Triton X-100 (PBT)
- cacodylate buffer
- barbital buffer
- tris buffer
- boric acid
- succinic acid
- and “any combination thereof”
- Exclusion: “wherein the hydrogel is devoid of an active pharmaceutical ingredient”
Scope effect: Claim 1 covers hydrogels that (a) are buffered aqueous systems, (b) sit in acidic pH, (c) use polyhydric alcohol + viscosity agent, and (d) avoid any disclosed API. Because it uses “consists essentially of” for the buffer component, it constrains what other buffering agents could be introduced without risking non-infringement.
Claim 11: alternative independent claim with “consists essentially of”
Claim 11 is another independent claim and is broader in listing “consists essentially of” components:
-
Hydrogel, pH 3 to 5
-
“consists essentially of”:
- polyhydric alcohol (1% to 30% w/w)
- viscosity increasing agent (0.1% to 5% w/w)
- buffering agent selected from the same restricted menu (acids/buffers including PBS/TBS/Tris-HCl/NaCl/PBT/Triton etc.)
- optionally at least one preservative
- optionally at least one neutralizing agent
- water (70% to 99% w/w)
- hydrogel “devoid of an active pharmaceutical ingredient”
-
Claim 12 and 13 then define “consists” flavors by limiting what the hydrogel consists of (e.g., with or without preservative and neutralizing agent).
Scope effect: Claim 11 is structurally closer to a formulation “composition recipe” claim because it explicitly states “consists essentially of” and includes optional preservative/neutralizing components as permissible additions.
What do the dependent claims add (and what do they narrow)?
pH specificity
- Claim 3: hydrogel has a pH of about 4.
- Claim 1/11: pH is 3 to 5 generally; claim 3 narrows to a specific point for closer match prosecution or enforcement.
Viscosity increasing agent specificity
- Claim 2: viscosity increasing agent is carboxypolymethylene.
- This is a high-value narrowing hook. Many hydrogels use other viscosity agents (e.g., carbomers, HPMC, xanthan). Claim 2 only captures formulations using the specified viscosity increasing agent.
Buffering system restricted to fewer acids
-
Claim 4: buffer consists essentially of citric acid, acetic acid, lactic acid, boric acid, succinic acid, or combinations.
- This narrows the allowable buffer menu subset.
-
Claims 8-10: these track with claim 1/11 but add tighter buffer selection and then concentration bands:
- Claim 8: buffer menu again “consists essentially of” the broader list (nearly identical to claim 1/4 menu)
- Claim 9: buffer present at about 0.01% to about 1% by weight
- Claim 10: buffer consists essentially of citric acid / citrate buffer / lactic acid / lactic acid buffer / tartaric acid buffer / malic acid / malic acid buffer / boric acid / succinic acid, or combinations
-
Claim 6: buffer present at about 0.1% to about 1% by weight
- This is one of the key numeric ranges for formulation matching.
Neutralizing agent hooks
- Claim 5: further comprising a neutralizing agent consisting essentially of trolamine (tromethamine), aminomethyl propanol, triisopropanolamine, or combinations.
- Claim 7: neutralizing agent present at about 0.1% to about 1% by weight.
Scope effect: Neutralizers are optional in claim 11, but if included, claim 5 narrows the permitted chemistries to a specific subset (trolamine and related amine-alcohol neutralizers). This matters for design-around because many buffer systems rely on NaOH, KOH, or other bases not listed.
Preservative hook
- Claim 14: preservative consists of benzoic acid.
Scope effect: If a competitor uses a different preservative (e.g., phenoxyethanol, sorbic acid, parabens other than benzoic acid, etc.), they avoid claim 14 but may still fall within claim 11/13 if preservative is optional and not restricted there.
How does “devoid of an active pharmaceutical ingredient” shape enforceability?
The phrase “wherein the hydrogel is devoid of an active pharmaceutical ingredient” is an enforcement boundary.
- If a formulation includes a therapeutic API (even at low dose), it is outside the “devoid” condition.
- If a formulation is a device adjunct, carrier, vehicle, buffered hydrogel excipient, or similar without an API, it is inside the formulation zone.
Practical implication: This is a patent aimed at base hydrogel compositions rather than finished drug products with actives. That does not remove value; it changes the target customers. It shifts risk toward injectable gels, topical gels, or preparation vehicles that may be sold or used without actives.
What is the patent landscape logic for this kind of claim set?
1) Likely “active-carrier” competition rather than API competition
Because the claims exclude active pharmaceuticals, the competitive set is typically:
- excipient-only hydrogels
- buffered hydrogel vehicles
- blank gels used as carriers or adjuncts in drug products
This reduces typical overlap with classic API patents, and it increases overlap with:
- formulation patents
- device/adjunct formulation patents
- stability and pH-controlled hydrogel excipient patents
2) “consists essentially of” creates both inclusion and design-around paths
- For the buffer component, “consists essentially of” limits the buffering agents. Competitors can design around by:
- selecting buffering systems outside the listed menu
- using neutralizers outside the listed subset if neutralizer is used
- Numeric ranges also provide carve-out levers:
- polyhydric alcohol 1% to 30%
- viscosity agent 0.1% to 5%
- water 70% to 99%
- buffer concentration bands (0.01% to 1% in dependent claims; 0.1% to 1% in claim 6)
3) Specific viscosity agent + specific pH point are the strongest narrow “match” claims
- Claim 2 (carboxypolymethylene) is a clean match target.
- Claim 3 (pH about 4) similarly matches a narrow specification.
- Competitors can avoid by selecting other viscosity agents and targeting other pH points inside or outside the ranges.
Where are the highest infringement risk formulation matches? (Claim-to-formulation mapping)
Highest-risk designs (tightest claim alignment)
1) Acidic buffered hydrogels (pH ~4) using:
- polyhydric alcohol 1% to 30% w/w
- carboxypolymethylene 0.1% to 5% w/w
- buffer from the listed acids/buffers in 0.1% to 1% or 0.01% to 1% bands
- no API
2) Neutralized versions using:
- trolamine/tromethamine and/or aminomethyl propanol/triisopropanolamine at 0.1% to 1% w/w
- benzoic acid if preservative is included (claim 14 scenario)
Lower-risk matches (design-around-friendly moves)
- Use viscosity increasing agents other than carboxypolymethylene (limiting reliance on claim 2).
- Use buffering systems not within the “consists essentially of” menu (limiting claim 1/4/8/10 capture).
- Include an active pharmaceutical ingredient (eliminate “devoid” compliance).
- Use neutralizing bases not listed for claim 5 (if neutralizer inclusion is part of the formulation strategy).
- Use preservatives other than benzoic acid (to avoid claim 14).
Claim coverage summary: what is clearly protected vs. what is conditional
| Claim |
Core limitation |
Main compliance “tripwires” |
| 1 |
Hydrogel, pH 3 to 5, devoid of API; polyhydric alcohol 1%-30%; viscosity agent 0.1%-5%; water 70%-99%; buffer “consists essentially of” listed menu |
Buffer must be from the listed set; API must be absent; component ranges must land within bands |
| 2 |
Claim 1 plus viscosity agent = carboxypolymethylene |
Viscosity agent chemistry |
| 3 |
Claim 1 plus pH about 4 |
Exact pH target point |
| 4 |
Claim 1 plus buffer subset = citric/acetic/lactic/boric/succinic acids (and combinations) |
Buffer subset restriction |
| 5 |
Claim 1 plus neutralizing agent limited to trolamine / aminomethyl propanol / triisopropanolamine |
Neutralizer chemistry and “consists essentially of” effect |
| 6 |
Claim 1 plus buffer amount 0.1%-1% |
Buffer concentration range |
| 7 |
Claim 5 plus neutralizer amount 0.1%-1% |
Neutralizer concentration range |
| 8 |
Claim 1 buffer is the full menu, still “consists essentially of” |
Buffer selection scope reaffirmed |
| 9 |
Claim 8 plus buffer amount 0.01%-1% |
Lower band concentration |
| 10 |
Claim 9 plus buffer subset (citric/citrate, lactic/lactic buffer, tartaric, malic, boric, succinic) |
Buffer subset restriction |
| 11 |
Alternate independent claim: hydrogel “consists essentially of” polyhydric alcohol + viscosity agent + buffer menu + optional preservative + optional neutralizing agent + water; pH 3-5; devoid of API |
Buffer menu must be from listed set; optional components constrained indirectly by other dependent claims |
| 12 |
Claim 11 hydrogel consists of polyhydric alcohol, viscosity agent, buffer, and water |
No optional preservative or neutralizer included |
| 13 |
Claim 11 hydrogel consists of polyhydric alcohol, viscosity agent, buffer, preservative, neutralizing agent, water |
Preservative and neutralizer included |
| 14 |
Claim 13 plus preservative = benzoic acid |
Preservative specificity |
What should business and R&D teams treat as “landscape-critical” next steps?
Design-around levers embedded in the claim text
1) Remove “devoid” condition by including an active (if strategically acceptable for the product concept).
2) Swap buffering chemistry to something outside the “consists essentially of” list.
3) Change viscosity increasing agent away from carboxypolymethylene (if not required).
4) Alter pH away from the protected window or target a different value (noting claim 1 still covers 3 to 5).
5) Neutralizer substitution away from listed neutralizing agents if neutralizer is part of the formulation.
6) Preservative substitution away from benzoic acid if preservative is used.
Commercial risk concentration
Risk concentrates in products marketed as:
- blank buffered hydrogels
- excipient-only hydrogels
- “vehicle” gels without actives
- systems sold under labeling that avoids API inclusion
Risk increases where the formulation aligns with:
- pH 4
- carboxypolymethylene
- citrate/citric, lactic, malic, boric, succinic style buffer sets
- amine-alcohol neutralizers (trolamine or related)
Key Takeaways
- US 11,285,098 claims acidic buffered hydrogels (pH 3 to 5) built from polyhydric alcohol (1% to 30%), viscosity increasing agent (0.1% to 5%), water (70% to 99%), and a buffer system limited by “consists essentially of” to a defined menu of acids/buffers.
- The composition is limited by a strict boundary: the hydrogel is “devoid of an active pharmaceutical ingredient.”
- The most enforceable, narrow hooks are carboxypolymethylene (Claim 2) and pH about 4 (Claim 3), plus subset buffer limitations (Claims 4 and 10) and preservative specificity (benzoic acid, Claim 14).
- Landscape and design-around should focus on buffer chemistry, viscosity agent identity, optional preservative/neutralizer choices, and the absence of API.
FAQs
1) Does US 11,285,098 cover hydrogels with therapeutic actives?
No. The claims require the hydrogel to be devoid of an active pharmaceutical ingredient.
2) What pH does the patent protect?
Claims 1 and 11 protect hydrogels with pH in the range of 3 to 5, and Claim 3 narrows to about pH 4.
3) Which viscosity increasing agent is singled out?
Claim 2 specifies carboxypolymethylene as the viscosity increasing agent.
4) Are the buffering agents restricted?
Yes. The buffer and/or buffering agent must “consist essentially of” a specified list of acids, buffer salts, and buffer systems (including citrate, acetic, lactic, malic, phosphate-family, Tris/PBS-type, and others listed).
5) What preservative is specified in the narrowest dependent claim?
Claim 14 specifies the preservative as benzoic acid.
References
[1] US Patent 11,285,098. “Composition in the form of a hydrogel…” Claims 1-14 (as provided in user prompt).
