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Patent landscape, scope, and claims: |
Scope and claims of US 5,603,929 (storage-stable ophthalmic acidic agent + polyquaternium 1/boric acid; excludes viscosity-enhancing polyvinyl alcohol)
US 5,603,929 is directed to a specific class of storage-stable ophthalmic compositions/formulations that combine: (i) one or more acidic ophthalmic agents (anti-glaucoma and/or non-steroidal anti-inflammatory drugs), (ii) a preservative system made of an antimicrobial polymeric quaternary ammonium compound plus boric acid, and (iii) an ophthalmically acceptable vehicle. The claims also contain a negative limitation: the composition must not contain a viscosity-enhancing amount of polyvinyl alcohol (PVA).
At a high level, the claim architecture is a classic Markush-driven structure with:
- a core independent claim (claim 1) that sets the structural and functional combination requirements,
- dependent claims (2–18) that narrow drug class, specific NSAIDs, polymer/quaternary ammonium molecular weight and concentration bands, and boric acid species/concentration/complexation, and
- a separate product claim (claim 19) focused on ophthalmic formulation embodiments (explicitly including diclofenac), with a further examples-style dependent claim (claim 20) listing a “comfort-enhancing” composition set (diclofenac, boric acid, mannitol, polyquaternium 1, and comfort-enhancing agent).
What is the invention “about” in claim terms?
The core novelty is the preservative pairing of:
- an antimicrobial polymeric quaternary ammonium compound (explicitly polyquaternium 1 in dependent claims), with
- boric acid (or ophthalmically active borate forms, including borate-polyol complexes),
in amounts that satisfy preservative efficacy requirements referenced to USP XXII and European Pharmacopeia (1994), while maintaining storage stability for an ophthalmic acidic active.
What must be present and what must be absent?
Must contain (claim 1):
- Therapeutically effective amount of one or more acidic ophthalmic agents selected from:
- anti-glaucoma agents, and/or
- non-steroidal anti-inflammatory agents.
- A preservative system comprising:
- antimicrobial polymeric quaternary ammonium compound, and
- boric acid,
in an amount effective to meet at least the minimum USP XXII and EP (1994) preservative effectiveness requirements.
- An ophthalmically acceptable vehicle.
Must not contain (claim 1 and downstream product claims):
- “a viscosity-enhancing amount of polyvinyl alcohol.”
This creates an exclusion that can matter in formulation design around polymers used for viscosity, including potential overlap with ophthalmic demulcents or tear-film polymers.
How broad is the independent claim (claim 1) and where are its main narrowing levers?
Claim 1 elements in plain claim scope
Claim 1 can be decomposed into 6 scope determinants:
- Route/application: “storage stable ophthalmic composition.”
- Active category: acidic ophthalmic agents limited to:
- anti-glaucoma agents, and/or
- non-steroidal anti-inflammatory agents.
- Preservative system: antimicrobial polymeric quaternary ammonium + boric acid with functional preservative effectiveness benchmark tied to USP XXII / EP (1994).
- Vehicle: ophthalmically acceptable vehicle (broad).
- Negative limitation: no viscosity-enhancing PVA.
- No additional compositional constraints in claim 1: claim 1 does not itself specify:
- polymer identity (beyond “polymeric quaternary ammonium compound”),
- polymer molecular weight,
- polymer concentration bands,
- boric acid concentration bands,
- borate-polyol complex ratio,
- which specific acidic NSAID (diclofenac etc.).
Practical breadth assessment
- Active scope is broad at the class level (anti-glaucoma and NSAIDs are both large families), but constrained to “acidic” ophthalmic agents.
- Preservative system scope is moderately broad because claim 1 covers “one or more” antimicrobial polymeric quaternary ammonium compounds (Markush-style but not enumerated in claim 1). Dependent claims narrow to polyquaternium 1 and provide molecular weight and concentration ranges.
- Borate system scope in claim 1 is “boric acid” (with dependent claim 14 expanding “ophthalmically active forms” and complexes).
- The PVA negative limitation provides a meaningful design-around boundary: any formulation relying on PVA as a viscosity enhancer would fall outside claim 1 if the limitation is interpreted as requiring “no viscosity-enhancing amount” of PVA.
Main “easy-to-narrow” levers for validity/infringement
For infringement/claim construction, the pivotal factual/legal questions are:
- Is the active an “acidic ophthalmic agent” of the claimed types?
- Is the preservative system actually a polymeric quaternary ammonium + boric acid, and does it meet the USP XXII / EP (1994) minimum preservative effectiveness requirements?
- Is there any viscosity-enhancing PVA?
For product design, the key levers are:
- choice of polymeric quaternary ammonium identity,
- polymer MW and concentration falling inside dependent claims,
- boric acid species and concentration inside dependent claims,
- whether a viscosity enhancer is PVA and whether it qualifies as “viscosity-enhancing” in the claim sense.
What does the Markush drug list do (claims 2–7)? Which NSAIDs are explicitly covered?
Claim 2: switch the active category to NSAID
- Claim 2 limits claim 1 to where the acidic ophthalmic agent is a non-steroidal anti-inflammatory agent.
Claim 3: chemical class of acidic NSAIDs
- Claim 3 defines the NSAID as an aryl- or heteroaryl-alkanoic acid, plus acceptable ophthalmic derivatizations:
- ophthalmically acceptable salt, ester, amide, or prodrug.
This language is important: it expands coverage beyond parent acids to known prodrug/salt/ester/amides that keep the NSAID “identity” in regulatory and chemical terms.
Claim 4: explicit NSAID family list
Claim 4 enumerates specific NSAIDs (and their acceptable ophthalmic derivatives):
- diclofenac
- flurbiprofen
- suprofen
- bromfenac
- ketorolac
- indomethacin
- ketaprofen
- and acceptable ophthalmic salts/esters/amides/prodrugs of each.
Claims 5–7: further subsets
- Claim 5 narrows claim 4 to diclofenac (and acceptable ophthalmic derivatives).
- Claim 6 narrows claim 4 to suprofen (and derivatives).
- Claim 7 narrows claim 4 to bromfenac (and derivatives).
Claim 19 and 20: product-level diclofenac embodiment
Claim 19 explicitly creates a formulation claim that includes:
- diclofenac (or ophthalmically acceptable salt/ester/amide/prodrug),
- and the same antimicrobial quaternary ammonium + boric acid system,
- excluding viscosity-enhancing PVA,
- plus an ophthalmic formulation structure.
Claim 20 then narrows further to a composition that comprises:
- sodium diclofenac,
- boric acid,
- mannitol,
- polyquaternium 1,
- and a comfort-enhancing agent.
From a scope perspective, claims 5 and 19 overlap on diclofenac; claim 19 is broader on excipients than claim 20, while claim 20 is closer to an “example” or commercial product composition.
Which preservative polymeric quaternary ammonium compounds and concentration ranges are covered (claims 8–13)?
Claim 8: polyquaternium 1 as the antimicrobial polymeric quaternary ammonium compound
- The antimicrobial polymeric quaternary ammonium compound is specifically polyquaternium 1.
Claim 9–10: number-average molecular weight bands
- Claim 9: polyquaternium 1 has number average molecular weight 2,000 to 30,000.
- Claim 10: tighter band: 3,000 to 14,000.
These are not generic “molecular weight is within a broad range” type limitations; they can define non-overlapping product options if competitor polymers fall outside.
Claim 11–13: concentration bands
- Claim 11: polyquaternium 1 at 0.00001 to 3.0 wt%.
- Claim 12: narrower: 0.001 to 0.1 wt%.
- Claim 13: tighter: 0.001 to 0.05 wt%.
Net effect:
- claim 1 could cover other polymeric quaternary ammonium compounds, but
- claim 8–13 lock in polyquaternium 1 and define multiple “nested” concentration/MW subsets.
What boric acid species and borate-polyol complexes are included (claims 14–18)?
Claim 14: “ophthalmically active forms”
Claim 14 broadens beyond “boric acid” to:
- boric acid,
- ophthalmically acceptable acid addition salts of boric acid,
- borate-polyol complexes.
Claim 15–17: boric acid concentration ranges
- Claim 15: boric acid concentration 0.3 to 5.0 wt%.
- Claim 16: 0.3 to 3.0 wt%.
- Claim 17: 0.5 to 2.0 wt%.
Claim 18: complex stoichiometry
- Borate-polyol complexes are water soluble with molar ratio:
- borate:polyol from 1:1 to 1:10.
This ratio can matter in infringement because changing the complexation chemistry (or using a different polyol) can move outside the stoichiometry band, depending on how “borate-polyol complex” is defined and tested.
What is actually claimed as a “formulation” vs an “ophthalmic composition” (claims 1–18 vs claims 19–20)?
Claim 1 uses “storage stable ophthalmic composition.” Claims 19–20 use “ophthalmic formulation.”
Substantively, they track the same core invention elements:
- diclofenac (for claim 19),
- preservative system (polyquaternium 1/boric acid) and excipient compatibility,
- absence of viscosity-enhancing PVA.
Claim 20’s excipient list tightens scope to:
- sodium diclofenac,
- boric acid,
- mannitol,
- polyquaternium 1,
- comfort-enhancing agent.
This can increase enforceability for a specific commercial composition and create a clean infringement map if a challenger uses the same excipients and their functional roles.
Patent landscape implications for claim scope: what competitors can design around?
Even without invoking external documents, the internal claim structure indicates likely design-around categories:
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PVA substitution
- Replace viscosity-enhancing PVA with a different viscosity enhancer that is not “polyvinyl alcohol.”
- Claim 1’s negative limitation triggers only for “viscosity-enhancing amount of polyvinyl alcohol.” If PVA is absent, the exclusion is not met.
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Move off the preservative pairing
- Use an antimicrobial system that is not “polymeric quaternary ammonium + boric acid,” or remove boric acid (or remove the polymeric quaternary ammonium component).
-
Change polymer identity away from polyquaternium 1
- Claims 8–13 are polyquaternium 1 specific. If a competitor uses another polymeric quaternary ammonium that still meets preservative effectiveness, they may avoid the dependent claim set, but may still implicate claim 1 (unless claim 1 requires polyquaternium 1, which it does not).
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Adjust polymer MW or concentration outside dependent bands
- Even if polyquaternium 1 is used, concentrations outside 0.001–0.05 wt% (and MW outside 3,000–14,000) could avoid the tighter dependent claims.
-
Move boric acid forms/concentration/complex ratio
- Use alternative borate species or borate-polyol complexes outside:
- boric acid 0.5–2.0 wt% band,
- or complex ratio 1:1 to 1:10 (for borate:polyol).
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Use NSAIDs outside the Markush list
- The dependent NSAID list is explicit. A non-listed NSAID might avoid dependent claims 4–7, though claim 1 and claim 2 still cover “non-steroidal anti-inflammatory agents” broadly if they are “acidic ophthalmic agents” and meet preservative requirements.
How strong is the patent estate for infringement coverage within the NSAID/anti-glaucoma market? (claim-scope-driven)
Strength against diclofenac products
The diclofenac pathway is reinforced twice:
- Dependent claim 5 (diclofenac within NSAID list), and
- Independent “formulation” claim 19 plus example-like claim 20 with sodium diclofenac + mannitol + polyquaternium 1 + boric acid.
This supports enforceability against diclofenac products using that preservative system, without PVA viscosity enhancement, and with polyquaternium 1/boric acid meeting USP/EP preservative efficacy.
Strength against bromfenac/suprofen products
Claims 6 and 7 explicitly capture suprofen and bromfenac subsets within the same preservative framework and the same PVA exclusion. Their enforceability depends on the exact polymer/boric acid selection and concentrations, but the drug identity is directly listed.
Anti-glaucoma coverage is less explicit in the provided claim set
Claim 1 covers “acidic anti-glaucoma agents,” but the dependent claims supplied focus on NSAIDs. The anti-glaucoma coverage could be broad for acidic agents but is not further enumerated in the claim list you provided, making the “claim-to-product mapping” more sensitive to what specific anti-glaucoma agent is used and whether it qualifies as “acidic.”
Key takeaways
- US 5,603,929 claims a preservative-engineered ophthalmic formulation combining acidic ophthalmic agents with a polymeric quaternary ammonium compound and boric acid, meeting USP XXII / EP (1994) preservative requirements, under a storage stable and no viscosity-enhancing PVA restriction.
- The claim set is structured for Markush coverage of NSAIDs that are aryl- or heteroaryl-alkanoic acids, with explicit dependent coverage for diclofenac, flurbiprofen, suprofen, bromfenac, ketorolac, indomethacin, and ketaprofen and their salts/esters/amides/prodrugs.
- Dependent claims narrow the preservative system to polyquaternium 1 with defined MW and wt% ranges, and narrow the borate system to boric acid forms and borate-polyol complexes with defined concentration and molar ratio.
- The strongest enforceability signal in the provided claims is for diclofenac formulations using polyquaternium 1 + boric acid and excluding PVA viscosity enhancers, with claim 20 offering a tighter compositional target (sodium diclofenac, boric acid, mannitol, polyquaternium 1, comfort-enhancing agent).
FAQs
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Do the claims require polyquaternium 1 specifically?
Claim 1 does not; it requires a “polymeric quaternary ammonium compound.” Polyquaternium 1 appears in dependent claim 8 and drives the MW and concentration ranges in claims 9–13.
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Does the patent cover borate-polyol complexes or only boric acid?
The core claim references “boric acid.” Dependent claim 14 explicitly includes ophthalmically active forms, including borate-polyol complexes, with ratio limits in claim 18.
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What role does the USP XXII and EP (1994) preservative requirement play?
It is a functional limitation in claim 1: the antimicrobial system must be present in amounts effective to meet at least the minimum preservative effectiveness requirements of those pharmacopoeias.
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How can formulators design around the patent’s PVA limitation?
By avoiding viscosity-enhancing amounts of polyvinyl alcohol. Using other non-PVA viscosity enhancers and keeping PVA out of the “viscosity-enhancing” category reduces risk under the negative limitation.
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Are diclofenac formulations explicitly protected even without polymer concentration/MW details?
Yes. Diclofenac is protected in claim 19 as part of the ophthalmic formulation concept; however, polyquaternium 1-specific concentration/MW limitations apply only to dependent claims like claim 20 and claims 8–13.
References
No external sources were provided or cited in the user prompt, so no reference list can be generated without introducing unprovided documents.
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