US Patent 10,842,872: Scope, Claims, Expiration, and Patent Landscape for Fluorescein/Benoxinate Ophthalmic Products

US Patent No. 10,842,872 covers a method of administering a topical ophthalmic composition containing fluorescein and benoxinate with defined impurity limits measured by a specified HPLC method. The patent does not broadly claim every fluorescein-benoxinate composition. Its commercial relevance depends on whether a competing product satisfies the concentration, impurity, storage-stability, and ophthalmic-use limitations.

The patent is directed to the product marketed in the United States as fluorescein sodium and benoxinate hydrochloride ophthalmic solution, commonly associated with Flurate. The independent claim combines a therapeutic-use limitation with a product-quality profile. That structure creates meaningful design-around opportunities, but it also creates potential infringement exposure for a product that matches the labeled formulation and impurity specifications.

What does US Patent 10,842,872 cover?

The patent claims administration of a composition containing two active components:

A fluorescein component, principally fluorescein sodium.
A benoxinate component, principally benoxinate hydrochloride.

The composition must have total impurities of approximately 1.5% or less by weight. The impurities must fall within a relative-retention-time range of approximately 0.10 to 1.90 under HPLC Method A.

The dependent claims add:

Stability after 12 months of storage.
A tighter total-impurity limit below approximately 1.0%.
Individual impurity peaks at relative retention times of approximately 0.43, 0.68, 0.74, and 0.79.
Fluorescein concentration of approximately 0.25% by weight.
Benoxinate concentration of approximately 0.40% by weight.
Fluorescein sodium and benoxinate hydrochloride.
Boric acid, povidone, purified water, hydrochloric acid, and preservatives.
Chlorobutanol as a preservative.
Ophthalmic uses including tonometry, gonioscopy, conjunctival procedures, corneal procedures, tear-fluid evaluations, and corneal anesthesia. (U.S. Patent No. 10,842,872, 2020)

The patent therefore combines three protection layers:

Composition identity.
Chemical-purity and stability specifications.
Use in ophthalmic procedures.

What is the independent claim in US 10,842,872?

Claim 1 is the principal enforceable scope. It requires all of the following:

Claim 1 limitation	Required element
Method	A method for administering a disclosing agent and anesthetic
Patient and site	An eye of a subject requiring an ophthalmic procedure
Route	Topical administration
Fluorescein	A fluorescein component
Benoxinate	A benoxinate component
Purity	Total impurities of about 1.5% or less by weight
Analytical definition	One or more impurities with relative retention times from about 0.10 to about 1.90
Test method	HPLC Method A

A product does not fall within claim 1 merely because it contains fluorescein and benoxinate. The impurity limitation and the HPLC method are central claim elements.

A potential infringement case would likely require analytical testing of the accused product, review of the applicable HPLC method, and evidence that the product is administered topically for an ophthalmic procedure. A product that is manufactured with a matching formula but never sold or used for the claimed ophthalmic administration may present a different infringement analysis from a marketed ophthalmic product accompanied by instructions for the claimed use.

How do the dependent claims narrow the patent scope?

Claims 2 through 11 focus on stability and individual impurity peaks. Claims 12 through 20 define the formulation. Claims 21 through 23 define clinical and diagnostic procedures.

Claims	Subject matter	Commercial significance
2-3	Total impurity after 12 months	Covers long-term stability performance
4-11	Individual impurity peaks at RRT 0.43, 0.68, 0.74, and 0.79	Creates product-specific analytical targets
12-17	0.25% fluorescein and 0.40% benoxinate, including sodium and hydrochloride salts	Closely tracks the conventional commercial formulation
18-20	Excipients and preservatives, including chlorobutanol	Narrows protection to specified formulation components
21-23	Ophthalmic procedures, including tonometry and corneal anesthesia	Defines the intended use environment

The strongest practical claims are likely claims 12, 15, 14, and 17 when combined with claim 1. Those claims correspond closely to a conventional fluorescein sodium 0.25% and benoxinate hydrochloride 0.40% product.

Claims 4 through 11 may be difficult to enforce without validated analytical testing because relative retention time is method-dependent. A competitor could challenge whether its impurity peak is sufficiently close to the claimed retention time, whether the HPLC conditions reproduce the patent method, and whether the impurity is present at the claimed concentration.

What formulation is protected by US 10,842,872?

The commercial formulation most closely aligned with the dependent claims contains:

Fluorescein sodium at approximately 0.25% by weight.
Benoxinate hydrochloride at approximately 0.40% by weight.
Boric acid.
Povidone.
Purified water.
Hydrochloric acid for pH adjustment.
An ophthalmic preservative, potentially chlorobutanol.

The claims do not require every listed excipient in the same claim. Claims 18 through 20 recite these components as additional limitations. A competitor using a different buffer, pH-adjusting agent, preservative, or viscosity modifier may avoid the narrower dependent claims while remaining exposed under claim 1 if its product satisfies the impurity profile.

The patent does not appear to claim a particular container, bottle, dropper, package, dosage volume, or unit-dose delivery system in the claims supplied. It also does not claim a specific manufacturing process in the claims supplied.

Does the patent cover Flurate or similar fluorescein-benoxinate products?

The claims are closely aligned with the standard fluorescein sodium and benoxinate hydrochloride ophthalmic solution used for topical anesthesia and visualization during eye procedures.

The relevant product category includes ophthalmic products used for:

Tonometry.
Gonioscopy.
Corneal examination.
Conjunctival procedures.
Tear-fluid and tear-film evaluations.
Minor ophthalmic procedures requiring topical corneal anesthesia.

A marketed product may be commercially relevant even if its label does not use every phrase in claims 21 through 23. Claim 1 is not limited to a single named procedure. It requires an ophthalmic procedure, while the dependent claims identify particular procedure categories.

FDA-approved fluorescein and benoxinate ophthalmic products are regulated as drug products rather than biologics. Biosimilar concepts do not apply to this small-molecule combination. Competition would normally arise through an abbreviated new drug application, a 505(b)(2) application, or an unapproved product subject to enforcement risk, rather than through the biosimilar pathway. (U.S. Food and Drug Administration, n.d.-a)

What is the Orange Book status of US Patent 10,842,872?

The supplied claims do not establish whether US 10,842,872 is listed in the FDA Orange Book. Patent listing is product- and NDA-specific. A patent may be relevant to an approved drug without appearing in the Orange Book, particularly where the patent claims a method of use, a formulation property, or a manufacturing feature that does not meet FDA listing requirements.

Orange Book significance depends on four questions:

Whether the patent owner or NDA holder submitted the patent for listing.
Whether the FDA accepted the listing.
Which NDA and active ingredient combination are identified.
Whether the listed claims cover the approved product or an approved method of use.

The Orange Book should be reviewed using the NDA number and the current patent listing data, not solely the patent document. A method-of-use listing may produce a narrower Paragraph IV dispute than a composition patent because a generic applicant may pursue a section viii statement that omits the patented use, where legally and regulatorily available. (U.S. Food and Drug Administration, n.d.-b)

When does US Patent 10,842,872 expire?

US Patent 10,842,872 issued on November 24, 2020. The patent’s ordinary term is generally measured from the earliest effective nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and other statutory adjustments. The issue date alone does not establish the expiration date.

Event	Date or rule
Patent issued	November 24, 2020
Ordinary term	Generally 20 years from the earliest effective nonprovisional filing date
Possible adjustment	Patent-term adjustment shown in USPTO records
Possible extension	Patent-term extension under 35 U.S.C. § 156, if granted
Terminal disclaimer	Must be checked in the patent file
Controlling source	USPTO patent record and patent-term data

Because the exact expiration date depends on the priority chain and any patent-term adjustment, a definitive date cannot be derived from the claims alone. The controlling record is the USPTO Patent Center file and the patent’s front-page term information. (United States Patent and Trademark Office, n.d.-a)

How strong is the patent estate for fluorescein and benoxinate?

The patent estate represented by US 10,842,872 is technically focused rather than broad. Its strength is highest against products that reproduce the commercial formulation and maintain the claimed impurity profile.

Risk factor	Assessment
Active ingredients	Strong overlap for products containing both fluorescein and benoxinate
Concentrations	Stronger for products at 0.25% fluorescein and 0.40% benoxinate
Purity limitation	Potentially strong if the product’s HPLC profile is within the claim
Stability limitation	Relevant to products maintaining the profile after 12 months
Procedure limitation	Strongest for labeled use in tonometry, gonioscopy, or corneal anesthesia
Manufacturing coverage	Limited in the claims supplied
Container or device coverage	Not present in the claims supplied
Broad composition coverage	Limited because claim 1 is a method claim
Design-around potential	Moderate to high, depending on analytical and labeling strategy

The patent’s main vulnerability is claim dependency on a defined analytical method. Relative retention times are not intrinsic product characteristics in the same way as molecular weight or active concentration. They depend on column chemistry, mobile phase, flow rate, detector conditions, temperature, and reference standard. The patent’s HPLC Method A therefore becomes important in both infringement and validity disputes.

What validity issues could affect US 10,842,872?

Potential validity issues include written description, enablement, indefiniteness, anticipation, obviousness, and claim construction.

Obviousness and anticipation

Earlier fluorescein-benoxinate ophthalmic products may establish that the active ingredients, concentrations, ophthalmic use, and excipients were known. The patent’s differentiation appears to depend substantially on impurity control and storage stability.

A prior-art reference would need to disclose, directly or inherently:

The claimed fluorescein-benoxinate composition.
The total impurity threshold.
The relevant RRT range under the claimed HPLC method.
The claimed stability period for claims 2 and 3.
The specific impurity peaks for claims 4 through 11.

A prior product with the same active ingredients may not anticipate the claims if its impurity profile was not disclosed or cannot be shown to have inherently met the claimed limits.

Indefiniteness

The phrases “about 1.5%,” “about 1.0%,” and relative retention times “about 0.43,” “about 0.68,” “about 0.74,” and “about 0.79” may generate claim-construction disputes. The patent specification and prosecution history would determine the permitted analytical tolerance.

The phrase “total impurity” also requires attention. The relevant questions include:

Which peaks count as impurities?
Are degradation products and process impurities treated identically?
Is the calculation based on area percent, weight percent, or a conversion factor?
Does the method quantify unknown peaks against a particular standard?
Are excipient-related peaks excluded?

Written description and enablement

The patent must support the impurity profile, analytical method, formulation, and 12-month stability limitations across the claimed scope. The broader claim covers any fluorescein and benoxinate composition satisfying the impurity profile, while the examples may focus on particular salts and excipients. That difference may become important in a validity challenge.

What Paragraph IV challenges could be filed against this patent?

A generic applicant seeking approval for a competing fluorescein sodium and benoxinate hydrochloride ophthalmic solution could evaluate several certifications:

Paragraph III certification if the applicant will wait until patent expiration.
Paragraph IV certification if the applicant asserts that the patent is invalid, unenforceable, or not infringed.
A section viii statement for a patented method of use that the proposed label omits, if FDA requirements permit the omission.

The practical Paragraph IV theories would likely focus on:

The product does not satisfy the claimed impurity limits.
The product’s impurity peaks do not have the claimed relative retention times.
The proposed label does not direct use for a claimed procedure.
The patent is invalid over earlier fluorescein-benoxinate products and stability disclosures.
The claims are indefinite because the HPLC method or analytical tolerances are not sufficiently defined.
The patent is not properly listed for the relevant NDA or product.

A Paragraph IV certification can trigger a Hatch-Waxman action if the patent owner or NDA holder files suit within the statutory period. The supplied information does not establish a particular Paragraph IV filing, 30-month stay, or final court judgment involving US 10,842,872. The FDA Orange Book and PACER records are the controlling sources for current regulatory and litigation status. (U.S. Food and Drug Administration, n.d.-b; U.S. Congress, 1984)

What patent litigation affects US 10,842,872?

The patent claims provided do not identify litigation. A complete litigation assessment requires docket-level review of:

Federal district court complaints.
Declaratory-judgment actions.
ANDA litigation.
Inter partes review petitions.
Post-grant review proceedings.
Patent ownership and assignment records.
Settlement agreements and consent judgments.

No litigation outcome can be inferred from issuance of the patent or from the existence of an Orange Book listing. If litigation exists, the most relevant disputes would likely concern claim construction of “total impurity,” reproducibility of HPLC Method A, product testing, and whether a generic label induces the claimed ophthalmic use.

Are there settlement agreements or licensing deals?

The patent claims alone do not disclose a license, covenant not to sue, co-development agreement, or generic settlement. Such agreements may appear in:

ANDA litigation dockets.
FTC pharmaceutical settlement filings.
SEC filings of public companies.
Patent assignment and merger records.
FDA exclusivity or listing materials.

A settlement would materially change launch timing if it included a permitted-entry date, authorized generic arrangement, supply agreement, or restriction on challenging the patent. No such commercial term is established by the patent document.

What generic launch risks exist?

A generic launch faces three separate risk categories.

Regulatory risk

The applicant must establish pharmaceutical equivalence, bioequivalence or an applicable waiver, quality, sterility, stability, and labeling compliance. Ophthalmic products face manufacturing controls for sterility, particulate matter, container closure integrity, and preservative performance.

Patent risk

The highest patent risk arises where the proposed product:

Uses fluorescein sodium at 0.25%.
Uses benoxinate hydrochloride at 0.40%.
Uses the same or similar excipients.
Maintains total impurities below 1.5%.
Shows impurity peaks corresponding to the claimed RRT values.
Is labeled for tonometry, gonioscopy, or corneal anesthesia.

Manufacturing risk

The product may be difficult to design around while maintaining acceptable color, stability, pH, preservative performance, and tolerability. Changing the impurity profile may require a different synthetic route, purification process, excipient system, packaging configuration, or storage condition. Those changes may create regulatory comparability issues even if they reduce patent exposure.

How does US 10,842,872 compare with broader formulation patents?

US 10,842,872 is narrower than a conventional composition-of-matter patent because it does not claim fluorescein or benoxinate molecules. It is also narrower than a broad formulation claim because the independent claim requires topical administration and a defined impurity profile.

Patent type	Typical scope	Relative position of US 10,842,872
Active-ingredient patent	Molecule or salt	Narrower and later-stage
Combination patent	Fluorescein plus benoxinate	Narrower because of impurity and use limits
Formulation patent	Ingredients, concentrations, pH, excipients	Comparable, but US 10,842,872 adds analytical limits
Stability patent	Shelf life or degradation control	Strong overlap with claims 2 and 3
Method-of-use patent	Ophthalmic procedure	Present in all claims through the administration requirement
Manufacturing patent	Synthesis, purification, filling, sterilization	Not apparent from the supplied claims

What geographic coverage does the patent provide?

US Patent 10,842,872 provides rights in the United States only. It does not automatically block products in Canada, Europe, Japan, China, or other markets.

International protection would require corresponding national or regional applications, such as:

European Patent Office filings.
Canadian filings.
Japanese filings.
Chinese filings.
Australian filings.
Other national-phase applications from an international application.

The existence, scope, and status of foreign counterparts must be assessed separately. A US patent’s impurity and HPLC claims may have been amended differently in foreign jurisdictions, and some jurisdictions may apply different standards to method-of-treatment claims.

What is the commercial exposure from this patent?

The exposed market is specialized but strategically important. Fluorescein-benoxinate products are used in ophthalmology, optometry, ambulatory eye care, and diagnostic procedures. Revenue exposure depends on:

The approved product’s annual sales.
The number of competing products.
Hospital and clinic purchasing contracts.
Generic substitution rules.
Product shortages.
The cost and feasibility of analytical design-around.
The remaining patent term.
Any listed exclusivity or litigation stay.

The patent does not protect the entire topical ophthalmic anesthetic market. It targets the combined fluorescein-benoxinate product category and, more specifically, products with the claimed impurity characteristics.

Key Takeaways

US Patent 10,842,872 is a method patent covering topical administration of a fluorescein-benoxinate ophthalmic composition.
The principal technical limitation is total impurity content of approximately 1.5% or less measured under HPLC Method A.
Dependent claims target 12-month stability, impurity peaks at RRTs of approximately 0.43, 0.68, 0.74, and 0.79, and the 0.25%/0.40% fluorescein-benoxinate formulation.
The claims closely track fluorescein sodium 0.25% and benoxinate hydrochloride 0.40% ophthalmic products.
The patent is narrower than a broad composition patent but may create meaningful launch risk for a directly substitutable generic.
The central infringement issues are product testing, HPLC reproducibility, impurity quantification, and labeled ophthalmic use.
Biosimilar competition is not relevant because the product contains small-molecule active ingredients.
Orange Book status, Paragraph IV activity, litigation, settlement agreements, and the exact expiration date require record-level verification from FDA, USPTO, and court databases.
Potential design-around routes include changing active concentrations, salts, excipients, preservative systems, impurity profiles, or labeled uses, subject to regulatory constraints.

FAQs About US Patent 10,842,872

Does US Patent 10,842,872 claim fluorescein sodium by itself?

No. The supplied claims require both a fluorescein component and a benoxinate component in a topical ophthalmic administration method.

Can a generic avoid the patent by changing the preservative?

Possibly for the narrower preservative-dependent claims, but changing the preservative alone may not avoid claim 1 if the product still satisfies the active-ingredient, impurity, HPLC, and ophthalmic-use limitations.

Is a product with 1.6% total impurities outside claim 1?

On the claim language supplied, a product at 1.6% total impurities would be outside the literal “about 1.5% or less” limitation, subject to the construction of “about” and the applicable measurement method.

Does the patent cover manufacturing the fluorescein-benoxinate solution?

The supplied claims are directed to administration, not manufacturing. They do not recite a manufacturing process.

Does the patent apply to injectable fluorescein or injectable benoxinate products?

No. The claims require topical administration to an eye for an ophthalmic procedure. Injectable products would not ordinarily satisfy those limitations.

References

United States Patent No. 10,842,872. (2020). Patent document and claims concerning fluorescein and benoxinate ophthalmic administration. United States Patent and Trademark Office.
United States Patent and Trademark Office. (n.d.-a). Patent Center and patent term adjustment information. https://patentcenter.uspto.gov/
United States Food and Drug Administration. (n.d.-a). Approved drug products with therapeutic equivalence evaluations. https://www.fda.gov/drugs/drug-approvals-and-databases/orange-book
United States Food and Drug Administration. (n.d.-b). Orange Book patent and exclusivity information. https://www.accessdata.fda.gov/scripts/cder/ob/
United States Congress. (1984). Drug Price Competition and Patent Term Restoration Act of 1984, Pub. L. No. 98-417, 98 Stat. 1585.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Bausch Lomb Ireland	FLUORESCEIN SODIUM AND BENOXINATE HYDROCHLORIDE	benoxinate hydrochloride; fluorescein sodium	SOLUTION/DROPS;OPHTHALMIC	211039-001	Mar 9, 2020		RX	Yes	Yes	10,842,872	⤷ Start Trial				PROCEDURES IN ADULT AND PEDIATRIC PATIENTS REQUIRING A DISCLOSING AGENT IN COMBINATION WITH A TOPICAL OPHTHALMIC ANESTHETIC.	⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Canada	3082603	⤷ Start Trial
China	111565761	⤷ Start Trial
European Patent Office	3710069	⤷ Start Trial
World Intellectual Property Organization (WIPO)	2019099739	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,842,872

Which drugs does patent 10,842,872 protect, and when does it expire?

Summary for Patent: 10,842,872