United States Patent 9,662,394 (Scope, Claims, and U.S. Landscape)
US Patent 9,662,394 claims an efinaconazole topical solution defined by a specific solvent/emollient system plus antioxidant and chelator controls designed to preserve color stability (initial colorless and post-storage colorless or pale yellow) under defined thermal stress. The claim set is built to capture both (i) the composition and (ii) a use method tied to nail fungal infection treatment.
What is the core claim architecture?
Claim 1 is the central composition claim
Claim 1 defines a solution composition with:
- Active: efinaconazole about 8% to about 12% (w/w)
- Solvent/emollients: water, C12-15 alkyl lactate, diisopropyl adipate, cyclomethicone, ethanol
- Stability package:
- BHT (butylated hydroxytoluene): about 0.01% (w/w) to about 2% (w/w)
- EDTA salt (ethylenediaminetetraacetic acid salt): about 0.0001% (w/w) to about 1.5% (w/w)
- citric acid: about 0.05% (w/w) to about 0.25% (w/w)
- Physical form: formulated as a solution
- Functional color limitations (performance-based boundaries):
- composition is colorless upon initial formulation
- and colorless or pale yellow after storage for three weeks at about 40°C
- Interdependence: the claim ties the specific amounts of BHT and EDTA salt to the color outcomes.
Dependent claims narrow key variables
Claims 2 to 15 tighten the parameter space:
- efinaconazole content: Claim 2 locks to about 10% (w/w)
- EDTA salt ranges and points: Claims 3, 4, 5, 6, 13
- citric acid ranges and points: Claims 7, 14, 15
- color measurement modes: Claims 8 and 9
- UV-vis performance after storage: Claim 10 (quantified AU thresholds at 400/500/600 nm after one month at 65°C)
- formulation performance: Claim 11 adds "pharmaceutically acceptable formulation that is effectively absorbed in the treatment of the nail."
- alternative composition envelope: Claims 12-15 shift from a general solvent/emollient list into a quantified ranges composition:
- ethanol 50% to 70% (w/w)
- cyclomethicone 10% to 15% (w/w)
- diisopropyl adipate 8% to 15% (w/w)
- C12-15 alkyl lactate 8% to 15% (w/w)
Claim 16 is the method of use
Claim 16 covers:
- method of treating a fungal infection
- administering a therapeutically effective amount of the Claim 11 formulation
- to a patient in need.
What is the claim scope in “freedom-to-operate” terms?
A. Where competitors can still enter without reading Claim 1
To avoid infringement of Claim 1, a competitor generally needs to defeat at least one “hard” element:
- Composition must be a solution with the listed core ingredients (water, C12-15 alkyl lactate, diisopropyl adipate, cyclomethicone, ethanol) plus efinaconazole.
- Antioxidant and chelator must fall within specified ranges:
- BHT: 0.01% to 2%
- EDTA salt: 0.0001% to 1.5%
- citric acid: 0.05% to 0.25%
- Functional color limitations tied to storage conditions:
- colorless initial
- colorless or pale yellow after 3 weeks at ~40°C
- Performance sufficiency is claim-built: the amounts of BHT and EDTA salt must be sufficient for the color outcomes.
B. Where “design-around” is constrained
The claim is broad in actives and solvents, but narrowed by stability performance. Designs that keep actives and typical solubilizers but change stability chemistry risk failing the functional color tests.
C. Dependent claim bottlenecks
- Claim 10 introduces quantitative UV-vis thresholds after one month at 65°C (0.4 AU at 400 nm; 0.1 AU at 500 nm; 0.1 AU at 600 nm).
- Claim 12 adds a constrained solvent/emollient ratio architecture (ethanol 50-70%, cyclomethicone 10-15%, diisopropyl adipate 8-15%, C12-15 alkyl lactate 8-15%).
- Claims 14-15 restrict citric acid narrower sub-ranges.
Detailed breakdown of each claim’s technical boundaries
Claim 1 (Composition; color-stable efinaconazole solution)
Defines: efinaconazole topical solution with stability package and functional color outcomes.
| Component |
Claim 1 range / requirement |
| Efinaconazole |
about 8% to 12% (w/w) |
| BHT |
about 0.01% to 2% (w/w) |
| EDTA salt |
about 0.0001% to 1.5% (w/w) |
| Citric acid |
about 0.05% to 0.25% (w/w) |
| Form |
solution |
| Color outcome |
colorless initially and colorless or pale yellow after 3 weeks at 40°C |
| Solvent system (required) |
water + C12-15 alkyl lactate + diisopropyl adipate + cyclomethicone + ethanol |
Key scope driver: BHT and EDTA salt amounts must be “sufficient” to meet the color requirements.
Claims 2-7 (Active loading and stability ingredient sub-sets)
- Claim 2: efinaconazole about 10% (w/w).
- Claim 3: EDTA salt 0.0001% to 0.0005% (w/w).
- Claim 4: EDTA salt about 0.00025% and BHT about 0.1%.
- Claim 5: EDTA salt 0.01% to 1% (w/w).
- Claim 6: EDTA salt about 0.1% and BHT about 0.1%.
- Claim 7: citric acid 0.075% to 0.15% (w/w).
These dependencies create multiple “islands” of claim coverage: some at very low EDTA salt levels (Claim 3/4) and some at substantially higher EDTA salt levels (Claim 5/6), paired with BHT fixed at ~0.1% in the specific dependent points.
Claims 8-10 (Color determination method and UV-vis performance)
- Claim 8: color determined by visual inspection.
- Claim 9: color determined by UV-vis absorbance values.
- Claim 10: after one month at 65°C, UV-vis thresholds:
- ≤ 0.4 AU at 400 nm
- ≤ 0.1 AU at 500 nm
- ≤ 0.1 AU at 600 nm
These claims tie infringement to measurable optical stability.
Claims 11-15 (Formulation acceptability and absorption; narrowed quantitative solvent envelope)
- Claim 11: formulation is pharmaceutically acceptable and effectively absorbed in treatment of the nail.
- Claim 12: quantified solvent/emollient ranges:
- ethanol 50%-70% (w/w)
- cyclomethicone 10%-15% (w/w)
- diisopropyl adipate 8%-15% (w/w)
- C12-15 alkyl lactate 8%-15% (w/w)
- Claim 13: EDTA salt about 0.00025% and BHT about 0.1% (aligning to Claim 4).
- Claim 14: citric acid 0.075%-0.15%.
- Claim 15: citric acid 0.075%-0.15% (duplicate narrow banding in dependent context).
Claim 16 (Method of treating fungal infection)
- Administration of therapeutically effective amount of formulation according to Claim 11
- for nail fungal infection context.
What is the practical patent landscape posture in the U.S.?
1) This patent reads as a formulation/stability patent
Across Claims 1-15, the differentiator is not a new antifungal mechanism. It is a specific formulation design with color-stability performance tied to BHT and EDTA salt levels plus citric acid and specific solvent system components.
2) The legal “pressure points” are stability tests
Competitors face two practical triggers:
- Functional color limitation (colorless initial; colorless or pale yellow after 3 weeks at 40°C)
- Optical UV-vis thresholds after 65°C storage
If a competitor’s product does not meet these performance criteria, they can argue outside the “sufficient amounts to ensure” requirement.
3) Claim 12 adds a quantitative architecture that can be used to map product overlap
Formulators that match typical efinaconazole solution solvents but do not align with the ethanol/cyclomethicone/lactate/adipate ranges may avoid the narrower dependent scope.
4) Claim 16 makes the formulation enforceable through use
Once a formulation falls within Claim 11, the method claim creates leverage by tying to therapeutic administration.
Where is the claim most vulnerable to obvious modifications?
The most “variant-aware” portion of the claim is the stability chemistry:
- BHT range is broad (0.01% to 2%).
- EDTA salt range is broad (0.0001% to 1.5%).
- Citric acid is moderate (0.05% to 0.25%).
The claim’s infringement boundary is therefore not simply ingredient presence. It is the performance outcome and the ability of BHT/EDTA salt at those levels to maintain color stability under the stated storage conditions.
Key Takeaways
- US 9,662,394 is a topical efinaconazole solution formulation patent with color-stability constraints that are enforced through functional requirements (3 weeks at 40°C) and, in dependent form, UV-vis thresholds (after one month at 65°C).
- Claim 1 is the operative breadth: it combines specific solvent/emollient system, BHT, EDTA salt, and citric acid at defined ranges with a color outcome requirement.
- Dependent claims narrow by locking efinaconazole loading (~10%), tightening EDTA/BHT combinations (including ~0.00025% EDTA salt with ~0.1% BHT), and specifying UV-vis AU cutoffs at 400/500/600 nm.
- Claim 12 adds a constrained ethanol/cyclomethicone/diisopropyl adipate/C12-15 alkyl lactate envelope that can materially affect product mapping for overlap.
- Claim 16 extends enforceability by claiming the use of the Claim 11 formulation for treating fungal infection, tying the formulation to therapeutic administration.
FAQs
1) Is US 9,662,394 primarily a drug-substance claim or a formulation claim?
It is a formulation claim: the novelty is the defined efinaconazole solution composition and a stability package controlling color.
2) Does Claim 1 require UV-vis testing to establish infringement?
Not for Claim 1. UV-vis is used in dependent Claim 9-10, while Claim 1 relies on color outcomes (initial and post-storage).
3) What excise points most clearly define the claimed formulation?
The formulation is defined by the combined presence of BHT, EDTA salt, and citric acid with the defined ranges, in a solution containing the specified solvent/emollient system, plus the required color stability outcome.
4) Which dependent claims are the tightest “numerical anchors”?
Claim 4 (EDTA salt ~0.00025% and BHT ~0.1%), Claim 10 (UV-vis AU limits at 400/500/600 nm after one month at 65°C), and Claim 12 (ethanol 50%-70%, cyclomethicone 10%-15%, diisopropyl adipate 8%-15%, C12-15 alkyl lactate 8%-15%).
5) Does the method claim add coverage beyond the composition?
Yes. Claim 16 ties use of the formulation (Claim 11) to treatment of a fungal infection in a patient, adding a therapeutic administration pathway for enforcement.
References
[1] US Patent 9,662,394 claims provided in prompt (Claims 1-16).
