United States Drug Patent 8,536,167: Finafloxacin Claims, Scope, Expiration, and Patent Landscape

U.S. Patent No. 8,536,167 protects methods of treating ophthalmic, otic, and nasal infections with finafloxacin compositions containing 0.1% to 1.0% finafloxacin. The commercially relevant embodiment is a 0.3% otic suspension at approximately pH 5, corresponding closely to Alcon’s Xtoro product. The patent’s strongest practical coverage is directed to otic treatment, including acute otitis externa and acute otitis media in patients with tympanostomy tubes.

The patent is a method-of-use patent rather than a broad composition-of-matter patent. It does not control finafloxacin as a molecule across all uses. Infringement depends on practicing a claimed treatment method with a composition meeting the concentration and, for narrower claims, pH and anti-inflammatory limitations.

What does U.S. Patent 8,536,167 cover?

U.S. Patent 8,536,167 covers the treatment of ophthalmic, otic, or nasal infections with a pharmaceutically effective amount of finafloxacin at a concentration of 0.1% to 1.0% weight/volume. The patent includes narrower claims for:

Nasal infections.
Acute otitis externa.
Acute otitis media in patients with tympanostomy tubes.
Finafloxacin concentrations of 0.1% to 0.5%.
Finafloxacin concentrations of 0.3% to 0.4%.
Formulations with a pH of 5.0 to 7.5.
Formulations with a pH of 5.0 to 6.0.
Formulations containing an anti-inflammatory agent.
Formulations containing dexamethasone.
Otic infections.

The claims are method claims. A product manufacturer would face infringement exposure when its product is used, marketed, labeled, or directed for a patented indication and the product satisfies the claimed concentration or formulation limitations.

How broad is independent claim 1?

Claim 1 is the principal claim:

A method for treating an ophthalmic, otic, or nasal infection comprising treating the infection with a pharmaceutically effective amount of a composition comprising finafloxacin at a concentration of 0.1 to 1.0 w/v%.

Its scope has four central elements:

Claim element	Scope
Treatment activity	Treatment of an infection
Anatomical site	Ophthalmic, otic, or nasal
Active ingredient	Finafloxacin
Concentration	0.1% to 1.0% w/v
Dose requirement	Pharmaceutically effective amount

The claim does not require dexamethasone, a specific pH, a particular dosage volume, a specific dosing frequency, or a particular dosage form on its face. A competing product could therefore fall within claim 1 even if it used a different excipient system, preservative, container, dosing schedule, or delivery device, provided the product contained finafloxacin in the claimed concentration range and was used to treat one of the listed infections.

The claim is narrower than a general claim to finafloxacin. It does not cover:

Systemic use of finafloxacin.
Treatment of infections outside the ophthalmic, otic, and nasal fields.
Concentrations below 0.1% or above 1.0%.
Non-therapeutic use.
A composition that contains finafloxacin but is not used in the claimed treatment context.

What do claims 2 through 10 add?

Claims 2 and 3: infection-specific limitations

Claim 2 narrows claim 1 to nasal infection. Claim 3 narrows it to acute otitis externa or acute otitis media with tympanostomy tubes.

Claim 3 is commercially important because Xtoro was approved for acute otitis externa, also known as swimmer’s ear. The tympanostomy-tube limitation also targets a clinically important pediatric and postoperative otic population.

A generic otic product labeled only for acute otitis externa could still implicate claim 1 and claim 10. It would not necessarily practice the narrower acute otitis media with tympanostomy tube limitation in claim 3 unless that indication were included in the labeling or treatment instructions.

Claims 4 and 5: concentration limitations

Claim 4 narrows the concentration to 0.1% to 0.5%. Claim 5 narrows it further to 0.3% to 0.4%.

The 0.3% to 0.4% range is the most commercially significant concentration limitation. Xtoro contains finafloxacin at 0.3% w/v, placing it directly within claim 5. A product at 0.3%, 0.35%, or 0.4% would fall within the literal concentration range, subject to the other claim requirements.

A product containing 0.2% finafloxacin would fall within claim 4 and claim 1 but not claim 5. A product containing 0.6% would fall within claim 1 but not claim 4 or claim 5.

Claims 6 and 7: pH limitations

Claim 6 requires a pH of 5.0 to 7.5. Claim 7 narrows the pH to 5.0 to 6.0.

Xtoro’s formulation has a pH of approximately 5.0, placing it within both pH ranges. These claims make pH a material limitation for a formulation-specific infringement analysis. A competing product at pH 6.5 could fall within claim 6 but not claim 7. A product at pH 7.8 would not meet either pH limitation, although it could still fall within claim 1, claim 4, claim 5, or claim 10.

Claims 8 and 9: anti-inflammatory combinations

Claim 8 requires an anti-inflammatory agent. Claim 9 specifies dexamethasone.

A finafloxacin-dexamethasone combination would face the narrowest and most direct claim coverage under claim 9 if it also satisfies the parent claim’s concentration and infection requirements. These claims do not cover a product containing dexamethasone alone or a product containing an unrelated antibiotic without finafloxacin.

Claim 10: otic infection

Claim 10 narrows claim 1 to otic infection. It is broader than claim 3 because it does not require acute otitis externa, acute otitis media, or tympanostomy tubes.

What formulation is most closely protected by U.S. Patent 8,536,167?

The formulation most closely aligned with the claims is:

Attribute	Commercially relevant embodiment
Active ingredient	Finafloxacin
Concentration	0.3% w/v
Route	Otic
Indication	Acute otitis externa
pH	Approximately 5.0
Dosage form	Otic suspension
Combination agent	No dexamethasone in the approved Xtoro product

This embodiment falls within claim 1, claim 4, claim 5, claim 6, claim 7, and claim 10. It would also fall within claim 3 when used for acute otitis externa. It would not implicate claim 9 because Xtoro does not use dexamethasone as the active anti-inflammatory component.

The patent therefore combines broad route-and-concentration coverage with narrower claims directed to the commercial product’s formulation conditions.

When does U.S. Patent 8,536,167 expire?

The patent has a statutory term generally calculated from the earliest effective nonprovisional or international filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and other statutory adjustments. Public patent records associate the patent family with a 2009 international filing chronology and an expected expiration in 2029. The Orange Book listing, rather than a simple 20-year calculation, is the controlling commercial reference for listed-drug patent timing.

Milestone	Commercial significance
Patent grant	U.S. Patent 8,536,167
Patent term	Expected to run into 2029, subject to applicable adjustments
FDA approval of Xtoro	December 2014
Orange Book relevance	Listed drug patent may delay approval of qualifying ANDAs
Earliest practical generic pathway	Paragraph IV challenge, patent expiration, or settlement-based entry

The precise effective expiration date should be taken from the current USPTO patent record and the current FDA Orange Book entry. A patent expiration date alone does not establish when a generic may launch because regulatory exclusivity, litigation stays, pediatric extensions, settlements, and other listed patents can affect entry.

What is the FDA and Orange Book status of Xtoro?

Xtoro is the U.S. brand product containing finafloxacin otic suspension, 0.3%. The FDA approved Xtoro under NDA 206301 for the treatment of acute otitis externa caused by susceptible strains of designated bacterial pathogens. The product is administered into the affected ear and is not approved as a systemic antibiotic product. [FDA, 2014]

The Orange Book is relevant because it identifies patents submitted by the NDA holder for the approved drug product and method of use. A listed method-of-use patent can require an ANDA applicant to submit a Paragraph IV certification if the applicant seeks approval before patent expiration and believes the patent is invalid, unenforceable, or not infringed. [FDA, 2024]

The presence of a patent in the Orange Book does not by itself establish that every generic finafloxacin product would infringe every claim. The analysis depends on:

The proposed label.
The product’s finafloxacin concentration.
The formulation pH.
The indication sought.
Whether dexamethasone or another anti-inflammatory agent is present.
Whether the ANDA seeks approval for all or only some patented uses.

What Paragraph IV challenges and litigation affect finafloxacin?

A Paragraph IV certification against U.S. Patent 8,536,167 would create litigation risk under the Hatch-Waxman framework if the NDA holder sued within the statutory period. A timely infringement action can trigger a 30-month stay of ANDA approval, subject to statutory exceptions and court decisions. [21 U.S.C. § 355]

The strongest Paragraph IV theories would likely involve:

Noninfringement based on a concentration outside the claimed range.
Noninfringement based on a pH outside claims 6 and 7.
A skinny label omitting a patented use.
Invalidity based on anticipation or obviousness.
Lack of enablement or written description for the full claimed concentration and infection scope.
Patent-term or listing challenges.

The strongest infringement theory would target a product at 0.3% finafloxacin, pH approximately 5, labeled for otic infection or acute otitis externa. That product would closely track the commercial embodiment and could satisfy several claims simultaneously.

No litigation or settlement conclusion should be inferred solely from the patent claims. A complete current litigation determination requires review of PACER, district-court dockets, Federal Circuit decisions, FDA correspondence, and current Orange Book records. The supplied claim text does not establish that a Paragraph IV notice, district-court action, or settlement agreement exists.

How strong is the patent estate for finafloxacin?

The estate is strongest against a direct Xtoro substitute and weaker against materially redesigned products.

Competitive product profile	Exposure to U.S. 8,536,167
Finafloxacin 0.3% otic product, pH 5.0	High
Finafloxacin 0.3% otic product, pH 6.5	High under claims 1, 5, and 10; possible claim 6 coverage
Finafloxacin 0.2% otic product	High under claims 1, 4, and 10
Finafloxacin 0.6% otic product	Claim 1 and claim 10 exposure, subject to use
Finafloxacin below 0.1%	Outside the stated concentration range
Finafloxacin above 1.0%	Outside the stated concentration range
Finafloxacin systemic product	Outside the claimed administration field
Finafloxacin with dexamethasone	Potential exposure under claims 1, 4, 5, 8, 9, and 10
Non-finafloxacin otic antibiotic	Outside this patent’s active-ingredient limitation

The patent has meaningful claim redundancy. A product can avoid one narrower claim while remaining exposed under claim 1 or claim 10. For example, changing the pH may avoid claims 6 and 7 but does not avoid the broader 0.1% to 1.0% concentration claim.

The main weakness is that the patent does not provide molecule-level exclusivity. A competitor can select another antibiotic, pursue a different concentration, target a different route, or design a label that omits a patented use. The patent also does not, based on the supplied claims, expressly cover manufacturing processes, containers, preservatives, particle-size specifications, or every possible finafloxacin dosage form.

What manufacturing and formulation barriers exist?

The claims create formulation barriers only where the formulation is used in the claimed treatment methods. They do not independently prevent manufacture of every finafloxacin-containing composition.

A competing manufacturer would need to assess:

Finafloxacin sourcing and active pharmaceutical ingredient rights.
Crystalline form and salt selection.
Suspension stability.
pH adjustment and buffering.
Preservative compatibility.
Container-closure performance.
Sterility or microbial-control requirements.
FDA approval requirements for an otic drug.
Separate patents covering manufacturing or formulation technology.

A formulation design that avoids the 0.1% to 1.0% range may avoid the literal concentration limitations, but it could create efficacy, safety, stability, or labeling problems. A different pH may avoid claims 6 and 7 while leaving claims 1, 4, 5, and 10 in place.

How does this patent compare with generic launch scenarios?

Scenario 1: Direct 0.3% otic substitute

This is the highest-risk scenario. A product matching Xtoro’s concentration and otic indication would likely face the most direct claim-read-on analysis. A Paragraph IV challenge would need to attack validity, enforceability, or infringement.

Scenario 2: Same active ingredient with a different concentration

A 0.2% product could remain within claims 1 and 4. A product above 0.5% but no higher than 1.0% could remain within claim 1. Concentration changes alone may not provide a complete design-around.

Scenario 3: Same active ingredient with a different pH

A pH outside 5.0 to 7.5 could avoid the pH-specific claims, but it would not avoid claim 1, claim 4, claim 5, or claim 10 if the concentration and otic use remain within those claims.

Scenario 4: Carve-out or skinny label

A generic applicant could seek approval for non-patented uses while omitting patented indications from labeling. The commercial value of this strategy depends on the extent of off-label substitution and whether the remaining label still induces infringement.

Scenario 5: Alternative antibiotic

A non-finafloxacin otic antibiotic would not meet the active-ingredient limitation of the patent. It would compete clinically with Xtoro but would not be a product-specific design-around of the finafloxacin claims.

What revenue exposure does the patent create?

The patent’s economic value is concentrated in the U.S. otic market for acute otitis externa and related ear infections. It has less direct value for systemic anti-infective markets because the claims do not cover systemic treatment.

Revenue exposure depends on:

Xtoro sales before and after patent expiry.
The number of ANDA applicants.
The commercial viability of a 0.3% generic otic product.
Whether a generic applicant obtains approval for all or only selected indications.
Any settlement-based entry date.
Additional Orange Book patents or regulatory exclusivity.
Physician and payer substitution behavior.

For valuation, the relevant cliff is not simply the expiration of U.S. 8,536,167. The analysis should model at least three dates: earliest legally permitted generic approval, settlement entry, and unrestricted generic launch after all enforceable listed rights expire.

Key Takeaways

U.S. Patent 8,536,167 is a method-of-use patent covering finafloxacin at 0.1% to 1.0% w/v for ophthalmic, otic, and nasal infections.
The commercially important claim set covers a 0.3% otic formulation, including pH ranges of 5.0 to 7.5 and 5.0 to 6.0.
Claim 5 directly captures the 0.3% to 0.4% range used by Xtoro.
Claim 3 covers acute otitis externa and acute otitis media with tympanostomy tubes.
Claims 8 and 9 address combination products containing an anti-inflammatory agent, including dexamethasone.
The patent is expected to remain relevant into 2029, subject to the official USPTO and Orange Book term records.
A direct 0.3% finafloxacin otic generic presents the highest infringement exposure.
Changing pH alone does not avoid the broader concentration and otic-use claims.
The patent does not provide composition-of-matter exclusivity over finafloxacin or cover all systemic uses.
Generic entry would most likely require patent expiry, a successful Paragraph IV challenge, a non-infringing label, or a settlement permitting earlier launch.

FAQs

Does U.S. Patent 8,536,167 cover Xtoro specifically?

The claims do not name Xtoro, but Xtoro’s 0.3% finafloxacin otic formulation and acute otitis externa indication correspond closely to multiple claims.

Can a generic avoid the patent by using 0.2% finafloxacin?

No complete design-around follows from that change alone. A 0.2% product remains within claim 1 and claim 4 if it is used for a covered ophthalmic, otic, or nasal infection.

Does the patent cover finafloxacin tablets or injections?

The supplied claims are directed to ophthalmic, otic, and nasal infections. They do not expressly cover systemic tablet or injectable use.

Would a finafloxacin-dexamethasone product face additional claim risk?

Yes. A qualifying combination could fall within claim 8 and claim 9 in addition to the parent concentration and infection claims.

Is a generic launch possible before the expected 2029 patent expiration?

It could be possible through a successful Paragraph IV challenge, a non-infringing label or formulation, an applicable settlement, or a determination that the patent is invalid or unenforceable. Approval timing must be evaluated against the full Orange Book and litigation record.

References

Food and Drug Administration. (2014). Xtoro (finafloxacin ophthalmic suspension) prescribing information. U.S. Department of Health and Human Services.
Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. U.S. Department of Health and Human Services.
United States Patent and Trademark Office. (2013). U.S. Patent No. 8,536,167, Finafloxacin compositions and methods of use. U.S. Department of Commerce.
21 U.S.C. § 355. Abbreviated applications and patent certifications under the Federal Food, Drug, and Cosmetic Act.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Fonseca Biosciences	XTORO	finafloxacin	SUSPENSION/DROPS;OTIC	206307-001	Dec 17, 2014		RX	Yes	Yes	8,536,167	⤷ Start Trial				TREATMENT OF ACUTE OTITIS EXTERNA	⤷ 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
Argentina	077372	⤷ Start Trial
Australia	2010266120	⤷ Start Trial
Brazil	PI1016257	⤷ Start Trial
Canada	2765852	⤷ Start Trial
Chile	2011003327	⤷ Start Trial
China	102470139	⤷ Start Trial
China	105687111	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,536,167

Which drugs does patent 8,536,167 protect, and when does it expire?

Summary for Patent: 8,536,167