US Patent 9,474,751: Claim Scope, Exclusivity, Orange Book Status and Generic Risk for Brimonidine/Timolol

US Patent 9,474,751 protects a twice-daily glaucoma treatment method using a fixed combination of 0.2% brimonidine tartrate and 0.5% timolol free base. Its commercial target is the Combigan ophthalmic solution, marketed by Allergan, now part of AbbVie. The patent does not broadly claim brimonidine, timolol, or every brimonidine/timolol formulation. Its central protection is narrower: a dosing regimen, a fixed composition, comparative efficacy against three-times-daily brimonidine monotherapy, and, in the final dependent claim, reduced adverse-event incidence.

The patent is most relevant to generic products labeled for twice-daily use with the same active concentrations. It is less likely to block products with different concentrations, different dosing instructions, or a different therapeutic indication unless those products are marketed in a way that induces performance of the claimed method.

What drug and product does US Patent 9,474,751 protect?

The patent covers the clinical use of a fixed-dose ophthalmic combination containing:

Component	Claimed amount
Brimonidine tartrate	0.2% w/v
Timolol free base	0.5% w/v
Benzalkonium chloride, in narrower claims	About 0.005% or 0.005% w/v
Sodium phosphate monobasic monohydrate	0.43% w/v in claim 4
Sodium phosphate dibasic heptahydrate	2.15% w/v in claim 4
pH	About 6.9 in claim 5
Route	Administration to an affected eye
Frequency	Twice daily

The claimed product corresponds closely to Combigan, a prescription ophthalmic solution approved for reducing elevated intraocular pressure in patients with glaucoma or ocular hypertension who require adjunctive or replacement therapy because intraocular pressure is not adequately controlled with topical beta-blocker monotherapy. The FDA-approved Combigan label identifies brimonidine tartrate 0.2% and timolol maleate equivalent to timolol 0.5% as the active ingredients.[2]

The claims use “timolol free base,” while the commercial product is generally described by its timolol-equivalent concentration and contains timolol maleate. That distinction can matter in claim construction and infringement analysis. A formulation containing timolol maleate may still satisfy a claim directed to 0.5% timolol free base if the salt provides the claimed amount of timolol active moiety. The analysis depends on the specification, prosecution history, and the court’s construction of the term.

What are the six claims of US 9,474,751?

The claim hierarchy creates one broad method claim and progressively narrower formulation and clinical-outcome limitations.

Claim 1: Core regimen and comparative efficacy

Claim 1 requires all of the following:

A patient with glaucoma or ocular hypertension.
Administration to an affected eye.
Twice-daily administration.
A single composition.
0.2% w/v brimonidine tartrate.
0.5% w/v timolol free base.
Efficacy equivalent to or as effective as brimonidine tartrate monotherapy at 0.2% administered three times daily.

The phrase “single composition” excludes a regimen in which brimonidine and timolol are administered separately, at least on the most natural reading of the claim. A patient receiving two separate bottles would present a materially different infringement position from a patient receiving one fixed-combination solution.

The claim is a method-of-treatment claim. It does not necessarily cover the composition as a standalone article. A manufacturer could face direct or induced infringement exposure when its product label instructs twice-daily use in glaucoma or ocular hypertension.

Claim 2: Preservative limitation

Claim 2 adds about 0.005% w/v benzalkonium chloride. The term “about” introduces a range rather than an exact numerical requirement. The range would be assessed through intrinsic evidence, formulation practice, prosecution history, and potentially expert testimony.

A product using a different preservative, no preservative, or a materially different benzalkonium chloride concentration may fall outside claim 2 while remaining within claim 1 if all claim 1 limitations are met.

Claim 3: General buffer and excipient limitation

Claim 3 requires the composition to include:

Sodium phosphate monobasic monohydrate;
Sodium phosphate buffer;
Sodium hydroxide;
Hydrochloric acid; and
Water.

The wording creates a potential construction issue because sodium phosphate monobasic monohydrate is itself a sodium phosphate buffer component. The claim may be interpreted as requiring the listed excipient and a phosphate-buffer system, rather than two chemically distinct buffer ingredients.

Claim 4: Specific formulation composition

Claim 4 narrows claim 1 by requiring:

0.005% w/v benzalkonium chloride;
0.43% w/v sodium phosphate monobasic monohydrate;
2.15% w/v sodium phosphate dibasic heptahydrate;
Sodium hydroxide;
Hydrochloric acid; and
Water.

This is the most formulation-specific claim before the pH limitation in claim 5. A generic product that substitutes a different buffer salt, uses different phosphate concentrations, or omits hydrochloric acid or sodium hydroxide could avoid literal infringement of claim 4, subject to the doctrine of equivalents.

Claim 5: pH limitation

Claim 5 requires the claim 4 formulation to have a pH of about 6.9. This limitation substantially narrows the technical scope because pH is measurable and ordinarily reported in product specifications and batch-release documentation.

A formulation with a pH outside the construction of “about 6.9” could avoid claim 5 while potentially remaining within claims 1 or 4.

Claim 6: Reduced adverse events

Claim 6 requires the full limitations of claims 1 through 5 and adds a comparative clinical result. The method must reduce the incidence of at least one of the following adverse events compared with 0.2% brimonidine tartrate monotherapy administered three times daily:

Conjunctival hyperemia;
Oral dryness;
Eye pruritus;
Allergic conjunctivitis;
Foreign-body sensation;
Conjunctival folliculosis; or
Somnolence.

Claim 6 is commercially important but difficult to assess from product composition alone. The required reduction is a clinical or statistical limitation. A plaintiff would likely need evidence concerning the label, clinical data, prescribing instructions, or actual use.

How broad is the scope of US Patent 9,474,751?

The effective scope is narrower than the presence of a fixed-dose brimonidine/timolol product might suggest.

Scope element	Breadth	Commercial implication
Disease	Glaucoma or ocular hypertension	Covers the principal Combigan indications
Route	Affected eye	Focuses on ophthalmic administration
Frequency	Twice daily	Vulnerable to products labeled for materially different schedules
Composition	Single composition	Targets fixed-combination products
Brimonidine	0.2% w/v brimonidine tartrate	Does not directly cover materially different strengths
Timolol	0.5% w/v timolol free base	Targets the standard timolol strength
Comparative efficacy	At least as effective as three-times-daily brimonidine monotherapy	Adds a performance limitation that may complicate proof
Excipients	Added only in claims 2 through 5	Creates formulation design-around options
Adverse events	Added in claim 6	Requires comparative clinical evidence

Claim 1 is the principal blocking claim. Claims 2 through 5 are formulation fallback claims. Claim 6 is a narrow outcome-based claim with potential evidentiary value but a higher proof burden.

The use of “comprising” generally makes the claims open-ended. A competing formulation may contain additional excipients and still satisfy the listed composition limitations. Adding an ingredient alone would not ordinarily avoid infringement.

What patents protect Combigan and brimonidine/timolol products?

US 9,474,751 is one part of the broader Combigan patent estate. The relevant patent categories are:

Patent category	Protection
Fixed-combination composition patents	Brimonidine and timolol in one ophthalmic formulation
Formulation patents	Preservatives, buffers, pH, stability, viscosity, and excipient combinations
Method-of-use patents	Twice-daily treatment, efficacy, tolerability, and patient populations
Manufacturing patents	Preparation, filling, sterilization, and product-quality processes
Regulatory exclusivity	FDA approval-based exclusivity, if applicable

The patent’s claims are method-oriented and do not eliminate the importance of separate composition or formulation patents. A generic applicant must evaluate the complete Orange Book listing for the reference-listed drug, not only US 9,474,751.[1]

Patent-family analysis should distinguish:

Continuations and divisionals;
Patents with overlapping priority claims;
Patent-term-adjustment periods;
Any terminal disclaimers;
Orange Book-listed patents;
Non-listed patents that may still create litigation or commercial risk.

The existence of a related patent does not establish that all family members have the same expiration date or enforceable scope.

When does US Patent 9,474,751 lose exclusivity?

US 9,474,751 was issued on October 25, 2016.[1] Its ordinary 20-year patent term is calculated from the relevant nonprovisional filing date, subject to patent-term adjustment, terminal disclaimer, and any other term modification. Public patent records commonly identify a projected expiration in approximately 2029 for this patent family, but the controlling date is the USPTO term calculation and any FDA Orange Book entry.

The patent’s practical exclusivity also depends on:

Whether it remains listed for Combigan;
Whether a generic applicant has submitted a Paragraph IV certification;
Whether litigation triggered a 30-month stay;
Whether the patent was disclaimed, expired, or removed from the Orange Book;
Whether a court issued an injunction;
Whether an authorized generic or settlement arrangement affects launch timing.

FDA patent listing and USPTO patent term records should be read together. Orange Book listing is a regulatory notice mechanism; it is not a final determination that every claim is valid or infringed.[1][3]

What is the Orange Book status of US 9,474,751?

The commercial relevance of US 9,474,751 turns on whether it is listed against Combigan’s NDA and whether an ANDA applicant certified against it.

For an ANDA applicant, the relevant certification could be:

Paragraph I: no patent information has been submitted;
Paragraph II: the patent has expired;
Paragraph III: the applicant will wait until expiration;
Paragraph IV: the patent is invalid, unenforceable, or will not be infringed.

A Paragraph IV notice can trigger patent litigation under the Hatch-Waxman Act. If the NDA holder sues within the statutory period, FDA approval may be stayed for up to 30 months, subject to statutory exceptions and court action.[4]

The patent claim language creates a particular Paragraph IV issue. An applicant may argue that its proposed label does not instruct:

Twice-daily administration;
Use of a single fixed combination;
Treatment of both glaucoma and ocular hypertension;
The claimed comparative regimen; or
The claimed adverse-event reduction.

The NDA holder may respond with an induced-infringement theory based on the product label, physician instructions, promotional materials, or the predictable use of the product.

Which generic entry risks exist for Combigan?

The principal generic-entry scenarios are as follows:

Scenario	Risk to patent estate	Likely timing effect
Generic with same strengths and twice-daily label	High for claim 1	Most direct Paragraph IV target
Generic with same actives but different excipients	Claim 1 remains relevant	Excipient changes may avoid claims 2-5
Generic with a different dosing instruction	May reduce method-claim exposure	Label strategy must be FDA-compliant
Separate brimonidine and timolol products	Avoids “single composition” limitation	Does not substitute commercially for the fixed combination
Product without benzalkonium chloride	May avoid claim 2 and later claims	Claim 1 remains the principal issue
Product with materially different pH	May avoid claim 5	Does not necessarily avoid claim 1
Product with a different active concentration	Potentially outside claim 1	Regulatory and clinical comparability issues arise

A generic applicant cannot simply remove a patented indication or instruction if the FDA-approved label requires the same use. Conversely, a properly supported section viii statement or carved-out label may reduce method-of-use exposure where the protected use can be omitted without preventing approval.

How strong is the patent estate for US 9,474,751?

The estate has moderate practical strength against an exact Combigan-style generic but weaker protection against formulation design-arounds.

Strengths

Claim 1 maps closely to the commercial fixed-dose product.
Twice-daily dosing is clearly stated.
The active concentrations are specific and commercially recognizable.
The “single composition” limitation targets the central product architecture.
Claims 4 and 5 provide detailed formulation fallbacks.
The product’s FDA label may provide evidence relevant to induced infringement.

Vulnerabilities

Brimonidine/timolol fixed combinations and twice-daily glaucoma therapy may face obviousness arguments based on earlier combination products and clinical knowledge.
“As effective as” can create indefiniteness, enablement, or proof issues depending on the specification and prosecution record.
“About” may invite disputes over numerical boundaries.
Claim 6 requires proof of reduced adverse-event incidence, not merely the presence of the claimed formulation.
A generic may design around preservative, buffer, pH, or dosing limitations.
The enforceable term may differ from a simple 20-year calculation because of patent-term adjustment or terminal disclaimer provisions.

The strongest infringement case is likely against a product with the same active strengths, the same twice-daily fixed-combination label, and a formulation substantially matching the claimed excipients. The weakest case is against a product with different strengths or a label that omits twice-daily treatment for the claimed diseases.

What competing drugs affect the commercial landscape?

Combigan competes with both fixed combinations and separate ophthalmic therapies.

Product or class	Active ingredients	Competitive relationship
Combigan	Brimonidine/timolol	Reference product for US 9,474,751
Cosopt	Dorzolamide/timolol	Alternative fixed combination
Simbrinza	Brinzolamide/brimonidine	Non-beta-blocker fixed combination
Separate brimonidine and timolol	Brimonidine plus timolol	Substitute regimen but not a single composition
Prostaglandin analogs	Latanoprost, bimatoprost, travoprost	Common first-line or combination alternatives
Rho-kinase inhibitor products	Netarsudil-containing products	Mechanistically differentiated alternatives
Nitric-oxide donating prostaglandin products	Latanoprostene bunod	Alternative pressure-lowering therapy

No biosimilar pathway applies to Combigan because it is a chemically synthesized small-molecule ophthalmic product, not a biologic. Competitive entry occurs through the ANDA pathway, subject to patent certifications and FDA requirements for pharmaceutical equivalence and therapeutic equivalence.

What litigation and settlement issues matter?

A complete litigation assessment requires review of federal complaints, ANDA notices, docket orders, settlement terms, and FDA approval records. The critical legal questions for this patent are:

Whether an ANDA applicant filed a Paragraph IV certification.
Whether Allergan or an affiliated NDA holder sued within the statutory period.
Whether a 30-month stay was imposed or lifted.
Whether the parties entered a confidential or publicly reported settlement.
Whether the settlement permits an agreed generic launch date.
Whether the agreement includes an authorized generic, supply arrangement, or license.
Whether related patents were asserted in the same action.

A settlement involving another Combigan patent would not automatically resolve US 9,474,751. Each patent must be analyzed by claim, listing status, asserted defenses, and agreed launch rights.

What licensing deals affect US 9,474,751?

The commercial holder of Combigan is Allergan, with AbbVie acquiring Allergan in 2020. The relevant commercial rights may include internal transfers, affiliated-company ownership changes, authorized-generic arrangements, or ANDA settlements.

A patent assignment is not the same as a license. Ownership and enforcement rights should be confirmed through USPTO assignment records, while commercial launch rights require review of settlement or licensing documents. No licensing arrangement should be inferred solely from a change in corporate ownership.[1][5]

Key Takeaways

US 9,474,751 is a method-of-treatment patent directed to twice-daily administration of a single 0.2% brimonidine tartrate/0.5% timolol composition.
Claim 1 is the primary commercial barrier for an exact Combigan generic.
Claims 2 through 5 add benzalkonium chloride, phosphate buffers, excipient concentrations, and approximately pH 6.9.
Claim 6 requires reduced incidence of specified adverse events compared with three-times-daily brimonidine monotherapy.
The patent does not broadly cover every brimonidine/timolol product.
Generic risk is highest for a product with the same strengths, fixed-combination format, and twice-daily label.
Formulation changes may avoid narrower claims but do not necessarily avoid claim 1.
No biosimilar pathway applies.
Orange Book listing, patent-term adjustment, Paragraph IV activity, and litigation records determine the practical exclusivity position.
The projected patent term appears to extend into approximately 2029, subject to the controlling USPTO and FDA records.

FAQs

Does US 9,474,751 cover Combigan itself?

It principally covers the method of using a Combigan-type fixed combination twice daily in glaucoma or ocular hypertension. Product-level protection may also arise from separate composition or formulation patents.

Can a generic avoid US 9,474,751 by removing benzalkonium chloride?

Removing benzalkonium chloride may avoid claim 2 and the claims that depend on it. It does not necessarily avoid claim 1, which does not require benzalkonium chloride.

Does claim 6 require every listed adverse event to be reduced?

No. Claim 6 requires reduction in at least one adverse event from the listed group, assuming all limitations of claims 1 through 5 are met.

Can separate brimonidine and timolol eye drops infringe the patent?

Separate products are less likely to satisfy the “single composition” limitation. The commercial and legal analysis would still depend on instructions, prescribing materials, and any induced-infringement theory.

Is a generic Combigan launch possible before the patent’s projected expiration?

Potentially, through a successful Paragraph IV challenge, a settlement license, a noninfringing label, patent invalidation or unenforceability, or expiration of the relevant patent term. FDA approval timing and litigation status control the launch window.

References

United States Patent and Trademark Office. (2016). U.S. Patent No. 9,474,751, Methods of treating glaucoma.
U.S. Food and Drug Administration. (n.d.). Combigan (brimonidine tartrate and timolol maleate ophthalmic solution) prescribing information.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Code. (2024). 21 U.S.C. § 355(j): Abbreviated applications and patent certifications.
AbbVie Inc. (2020). Current report on Form 8-K regarding completion of acquisition of Allergan plc.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2003228480	⤷ Start Trial
Brazil	0302584	⤷ Start Trial
Canada	2440764	⤷ Start Trial
China	100558364	⤷ Start Trial
China	101664414	⤷ Start Trial
China	112219061	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 9,474,751

Summary for Patent: 9,474,751