Scope and claims of US Patent 8,268,299 and the US patent landscape for self-preserved ophthalmic zinc–borate–polyol formulations containing travoprost
US 8,268,299 is directed to a multi-dose, self-preserved ophthalmic composition that combines zinc ions (from zinc chloride) with borate (as boric acid) and a specific borate/polyol antimicrobial system (propylene glycol plus sorbitol), tuned to low “anionic species” and USP performance. Claim 1 sets the backbone; dependent claims narrow to low multivalent buffering anions/cations, include travoprost and other prostaglandin analogs, and optionally add polyoxyl 40 hydrogenated castor oil plus pH 5.5–5.9. Claims 22–28 present a dedicated travoprost-included embodiment and include “consisting of” style limitations that can tighten infringement scope.
What is US Patent 8,268,299 claim 1 actually covering (scope of zinc–borate–polyol self-preserved ophthalmic compositions)?
Claim 1 (independent) covers the formulation concept, not the device or dosing regimen, with five main technical requirements:
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Product form and functional requirement
- Multi-dose, self-preserved ophthalmic composition
- Exhibits sufficient antimicrobial activity to satisfy USP 27 preservative efficacy requirements (a functional limitation that can become a central infringement and validity battleground via expert testing)
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Zinc level
- Zinc ions at 0.04 to 0.4 mM
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Borate and polyol ranges
- Borate concentration: 0.1 to 2.0% w/v
- Polyol concentration: 0.25 to 2.5% w/v
- Polyol makeup:
- Propylene glycol: 0.25 to 1.25% w/v
- Sorbitol: 0.05 to 0.5% w/v
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Low anionic species constraint
- Concentration of anionic species < 15 mM
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Implicit composition chemistry boundary
- Claim 1 does not explicitly require “no other multivalent cations,” but that boundary is introduced in dependent claims (e.g., claim 2/3/15).
Practical scope implication: any accused product that includes the defined zinc + borate + propylene glycol/sorbitol at overlapping ranges and meets USP preservative efficacy and the anionic species <15 mM constraint can fall within claim 1 even if the rest of the formulation differs, unless the anionic species and USP efficacy tests are not met.
How do dependent claims narrow US 8,268,299 (multivalent anions/cations, zinc source, and the travoprost-specific embodiments)?
Claim 2 and 3: “multivalent buffering anions < 5 mM” and “other multivalent metal cations < 5 mM”
- Claim 2: adds a tighter low multivalent buffering anion threshold: <5 mM
- Claim 3: adds:
- multivalent buffering anions <5 mM
- multivalent metal cations other than zinc <5 mM
Scope impact: these are narrower, likely aimed at excluding common ophthalmic buffering systems that generate additional multivalent species or counterions.
Claims 4–6 and 9–11: therapeutic agent overlay (bimatoprost/latanoprost/travoprost/unoprostone; travoprost singled out)
- Claim 4: “therapeutic agent” added on top of the self-preserved system
- Claim 5: therapeutic agent selected from bimatoprost, latanoprost, travoprost, unoprostone
- Claim 6: further specifies travoprost
- Claims 9–11: repeats these overlays but in the context of claim 9’s tighter ionic constraints (multivalent anions/cations <5 mM and borate 0.5–1.2% w/v)
Scope impact: claim 1 can read on non-prostaglandin uses; claims 5/6 and 10/11 explicitly capture major glaucoma prostaglandin analogs, with travoprost being the most directly targeted.
Claim 7 and 12: polyoxyl 40 hydrogenated castor oil + pH 5.5–5.9
- Claim 7: adds polyoxyl 40 hydrogenated castor oil and requires pH 5.5–5.9
- Claim 12: does the same for the tighter dependent claim context (claim 11)
Scope impact: this likely maps to excipient packages used in certain glaucoma formulations (non-ionic surfactant/micelle stabilizer behavior can also relate to antimicrobial performance or solubilization stability).
Claim 8: optional non-ionic surfactant
- Adds any non-ionic surfactant, broadening while remaining within the defined ionic/borate/polyol framework.
Claim 13 and 14: zinc chloride as zinc source; concrete exemplified concentrations
- Claim 13: zinc ions provided by zinc chloride at 0.001 to 0.005 w/v%
- Claim 14: a specific numerical recipe:
- propylene glycol: 0.75% w/v
- boric acid: 1.0% w/v
- zinc chloride: 0.0025% w/v
- (and these align with the travoprost embodiments below)
Scope impact: depending on the prosecution history and how the patent defines “w/v%” vs mM conversion, these claims can become a litigation pivot if an accused product uses a different zinc salt or slightly different concentration.
Claim 15: “no multivalent buffering anions” and “no multivalent cations other than zinc”
- Claim 15 states the composition:
- does not contain multivalent buffering anions
- does not contain multivalent cations other than zinc
Scope impact: this is a clean exclusionary boundary that can be used to “design around” (buffer selection, ionic strength management, and excipient choice).
Claims 16–19: additional “anionic species” cutoffs (<10 mM and <5 mM)
- Claim 16: <10 mM
- Claim 17 and 19: <5 mM
- Claim 18: for the tighter dependent claim: also <10 mM
Scope impact: these are gradient limitations. In infringement, if an accused product’s measured “anionic species” is >10 mM but <15 mM, it may still fall under claim 1 but not claims 16/17/18/19.
Claims 20–21: explicit zinc concentration range overlap
- claim 1 already covers 0.04–0.4 mM; these claims restate zinc range in separate claim context.
What is the independent travoprost formulation coverage in US 8,268,299 claims 22–28?
Claims 22 and 26–28 are especially significant because they articulate a travoprost-specific composition with additional constraints and, in claims 26–28, “consisting of” language.
Claim 22 (independent within the provided set)
A multi-dose, self-preserved ophthalmic composition including:
- effective amount of travoprost
- zinc ions 0.1 to 0.4 mM provided by zinc chloride
- borate and polyol:
- boric acid 0.5 to 1.2% w/v
- polyol includes:
- propylene glycol 0.25 to 1.25% w/v
- sorbitol 0.05 to 0.5% w/v
- water
- wherein:
- anionic species <10 mM
- antimicrobial activity meets USP 27
- no multivalent buffering anions and no multivalent cations other than zinc
Claim 23
Adds polyoxyl 40 hydrogenated castor oil with pH 5.5–5.9.
Claim 24 (specific recipe)
- travoprost 0.004% w/v
- zinc chloride 0.0025% w/v
- boric acid 1.0% w/v
- propylene glycol 0.75% w/v
- sorbitol 0.25% w/v
- non-ionic surfactant 0.5% w/v
Scope impact: This is a high-value infringement target if an accused product’s exact composition matches. Exact-match claims are typically easier for claim charts but also can be more straightforward to avoid through parameter tuning.
Claim 25
Reiterates “no multivalent buffering anions” and “no multivalent cations other than zinc.”
Claim 26 (consisting of)
A “multi-dose, self-preserved ophthalmic composition, consisting of”:
- travoprost
- zinc chloride (0.1 to 0.4 mM)
- polyoxyl 40 hydrogenated castor oil
- boric acid + propylene glycol + sorbitol in the listed ranges
- sodium hydroxide and/or hydrochloric acid for pH
- water
- wherein:
- anionic species <10 mM
- USP 27 preservative efficacy satisfied
- no multivalent buffering anions and no multivalent cations other than zinc
- pH 5.5–5.9
Scope impact: “consisting of” generally narrows allowable components, potentially excluding additional buffers, additional salts, or other ionic excipients that would otherwise be considered “insubstantial.”
Claim 27 (consisting of + exact concentrations)
Hardens the claim to:
- travoprost 0.004% w/v
- zinc chloride 0.0025% w/v
- polyoxyl 40 hydrogenated castor oil 0.5% w/v
- boric acid 1.0% w/v
- propylene glycol 0.75% w/v
- sorbitol 0.25% w/v
- NaOH and/or HCl to adjust pH
- water
- wherein:
- anionic species <5 mM
- USP 27 preservative efficacy satisfied
- no multivalent buffering anions and no multivalent cations other than zinc
- pH 5.5–5.9
Claim 28 (consisting of but slightly higher anionic species cap)
Similar to claim 27 but with:
- anionic species <15 mM (and still no multivalent buffering anions/cations other than zinc)
Scope impact: claim 27 is tighter than claim 28 on anionic species, but both are more compositionally constrained via “consisting of” language.
How strong is infringement coverage if a competitor uses zinc pyrithione, different borates, or different polyols (design-around vectors)?
Based strictly on the claim text provided:
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Zinc source: claim 1 does not state the zinc must be zinc chloride; claim 13 does, and the travoprost embodiment claims 22 and 26–28 explicitly require zinc chloride (for “zinc ions provided by zinc chloride”).
- A design-around for travoprost embodiments could use another zinc salt if that avoids the “provided by zinc chloride” limitation. Claim 1 still may read if the zinc concentration and other requirements are met.
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Borate identity: claim 1 specifies borate range but not “boric acid”; the travoprost embodiment claims specify borate “being present as boric acid” or state borate being present as boric acid in the composition.
- A design-around for travoprost claims is possible by using a different borate species, assuming it still satisfies the concentration and ionic species constraints and maintains USP efficacy.
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Polyol identity: the polyol is defined as comprising propylene glycol and sorbitol with specific ranges. Substituting other polyols risks losing the polyol definition unless the formulation still includes both propylene glycol and sorbitol within the claimed ranges.
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“Anionic species” metric: the patent uses measurable caps (<15 mM, <10 mM, <5 mM) and “multivalent buffering anions” exclusions. Competitors can attempt to alter buffering counterions and ionic strength to move the anionic species count above a cap.
- This becomes an evidentiary fight because “anionic species” is not inherently standard across formulary contexts; measurement method can determine infringement.
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“No multivalent buffering anions” and “no multivalent cations other than zinc”: this is a direct exclusionary design-around vector.
- Avoiding multivalent buffering anions and avoiding any multivalent cations besides zinc may be feasible with buffer selection and excipient ionic hygiene.
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“Consisting of” claims 26–28: these limit what components can be present, excluding additional excipients that could be argued to be beyond those listed.
What patents might be around US 8,268,299 in the self-preserved glaucoma formulation space (landscape drivers)?
The claim set you provided describes a formulation strategy that is commonly adjacent to other ophthalmic IP categories:
- preservative systems (including antimicrobial efficacy and self-preserving behavior),
- zinc/metal-ion antimicrobial synergy,
- buffering systems affecting ionic species and preservative efficacy,
- prostaglandin analog formulation stability (travoprost compatibility, solubilizers/surfactants),
- excipient packages, including non-ionic surfactants and pH constraints.
But the question asks for a detailed US patent landscape scope and claims for US 8,268,299 specifically. Without the patent’s bibliographic data (assignee, filing/grant dates, continuation family, prosecution history), and without an Orange Book tether to a specific FDA product and NDA/ANDA reference listed drug, a complete landscape mapping of US patents “covering” the same commercial product cannot be produced from the claim text alone.
Per the constraint set, only the material that can be supported directly from the claim language is incorporated here.
How does USP 27 preservative efficacy function as a claim limiter (what does it do to the scope)?
In US 8,268,299, USP 27 preservative efficacy is integrated into the independent claim logic. Two legal/technical effects follow from that structure:
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Functional infringement hook
- A formulary can meet structural requirements (zinc/borate/polyol ranges and anionic species caps) yet still fall outside if it does not achieve the required antimicrobial performance under the USP protocol.
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Litigation evidence control point
- The preservative efficacy becomes a core factual issue, with testing protocols, sample preparation, and method comparability potentially controlling outcomes.
What is the “anionic species” limitation doing across the claim set?
The claim uses three tiers:
- claim 1: <15 mM
- claim 22: <10 mM
- claims 26–27: <10 mM (claim 27 uses <5 mM)
- claim 28: <15 mM
- claims 16–19: nested caps in dependent forms (<10 mM and <5 mM)
Scope implication: this behaves like a compositional fingerprint. Competitors can attempt to exceed the cap by adding ionic species that count as “anionic species” under the patent’s definition or test method, even if zinc/borate/polyol concentrations overlap.
Claim chart-ready breakdown: key elements mapped to likely “infringement gates”
| Claim element |
What it requires |
Main infringement gate |
| Multi-dose, self-preserved ophthalmic composition |
No added preservative beyond composition’s self-preserving system |
Whether antimicrobial activity is intrinsic |
| Zinc ions |
0.04–0.4 mM (claim 1) or 0.1–0.4 mM (travoprost embodiments) |
Zinc concentration measured as ionic zinc |
| Zinc source |
zinc chloride explicitly in claims 13 and 22/26–28 |
Salt selection and “provided by” requirement |
| Borate |
borate 0.1–2.0% w/v (claim 1); boric acid 0.5–1.2% w/v (travoprost claims) |
Borate identity and concentration |
| Polyol system |
propylene glycol and sorbitol in specified ranges |
Presence of both components within ranges |
| Ionic caps |
anionic species <15 mM (claim 1); tighter caps in dependents |
Measurement of “anionic species” |
| Multivalent constraints |
optional in claim 1, explicit in dependent/travoprost claims |
Buffer/counterion selection |
| Therapeutic agent |
travoprost or other prostaglandin analogs |
Drug loading and identity |
| Excipients and pH |
polyoxyl 40 hydrogenated castor oil and pH 5.5–5.9 (certain dependents) |
Excipients present and pH window |
| “consisting of” |
claims 26–28 list components allowed |
Exclusion of additional components |
When does US 8,268,299 lose exclusivity or become vulnerable to generic entry?
The claim text alone does not contain:
- filing and priority dates,
- patent term adjustment,
- terminal disclaimers,
- the relationship to any FDA approval (NDA/ANDA),
- whether it is listed in the Orange Book for a specific drug product,
- whether it covers a formulation used by an approved reference listed drug.
As a result, a timeline for exclusivity or generic entry risk cannot be determined from the information provided.
Key Takeaways
- US 8,268,299’s core claim 1 targets a self-preserved ophthalmic formulation system combining zinc ions + borate (range-based) + propylene glycol + sorbitol, constrained by low anionic species and meeting USP 27 preservative efficacy.
- Dependent claims tighten ionic boundaries using multivalent buffering anion and other multivalent cation caps (<5 mM) and exclude certain ionic species (claim 15).
- Travoprost coverage is explicit and numerically anchored: claims 22–28 require travoprost with zinc chloride, boric acid, and the propylene glycol/sorbitol system, and add anionic species caps plus pH 5.5–5.9 where specified.
- Claims 26–28 use “consisting of”, which increases component-level rigidity and makes excipient substitutions a key design-around lever.
- The most litigation-sensitive limitations are the USP 27 preservative efficacy functional requirement and the measurement/definition of “anionic species.”
FAQs
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Can an accused product infringe if it meets zinc/borate/polyol ranges but fails USP 27 preservative efficacy in testing?
If the functional USP efficacy limitation is not met, infringement can be defeated even when composition ranges overlap.
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What’s the practical difference between “anionic species <15 mM” and “anionic species <5 mM” in this patent?
Lower caps narrow the acceptable ionic profile, increasing design-around feasibility by shifting buffering/counterions or ionic strength.
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Do the travoprost claims require zinc chloride specifically?
Yes. The travoprost formulation claims you provided require zinc ions provided by zinc chloride.
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How do “consisting of” claims 26–28 change design-around strategies?
They restrict allowable formulation components to the listed set, increasing risk of non-infringement by excluding additional excipients/salts.
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Do the claims cover multiple prostaglandin analogs or only travoprost?
The claim set includes bimatoprost, latanoprost, travoprost, and unoprostone in dependent claims, with travoprost called out in multiple narrower embodiments.
References
- US Patent 8,268,299. Claims provided in user prompt (claim 1–28).
