Patent 9,492,384 Landscape and Claim Scope for Desonide Oil-in-Water Microemulsion Dermal Delivery
United States Patent US 9,492,384 claims a desonide topical delivery system built around an oil-in-water (O/W) microemulsion or sub-micron emulsion with a defined oil-phase surfactant package, water-phase surfactant package, and a post-formation addition of a water-miscible amphiphilic solvent. The independent claim is broad on the microemulsion architecture and oil-phase component classes, but it is narrower on the functional requirement that desonide is located in the water phase or both phases and on the structural sequence that the amphiphilic compound is added after formation and is miscible in the water phase. Dependent claims narrow with a hydrophilic-to-lipophilic surfactant ratio window, specific amphiphilic solvents, and an HLB aggregation range.
What is US 9,492,384 and what does it claim about desonide microemulsions?
Core invention in one line:
An O/W microemulsion or sub-micron emulsion for dermal delivery of desonide, where the formulation has (i) an oil phase containing a defined set of lipophilic components and at least one lipophilic surfactant, (ii) a water phase containing at least one hydrophilic surfactant and water, and (iii) a non-surfactant amphiphilic compound added after microemulsion formation that is miscible in the water phase, with desonide in the water phase or in both phases.
Independent claim scope (Claim 1) decoded into enforceable elements
Claim 1 is an apparatus/composition claim with multiple conjunctive limitations:
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Composition type
- “Oil in water microemulsion or sub-micron emulsion” for dermal delivery.
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Active and phase location
- Desonide is present in the formulation.
- Desonide is in the water phase or in both oil and water phases.
- This is a key polarity constraint. Formulations where desonide is effectively restricted to the oil phase (and not in the water phase) risk non-infringement on this element.
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Microemulsion architecture
- Oil phase “dispersed throughout” water phase, i.e., a classic O/W dispersed oil droplet structure.
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Oil phase composition requirement
- The oil phase comprises:
- At least one component selected from:
- animal oil, mineral oil, vegetable oil, silane, siloxane, ester, fatty acid, fat, halogen compound, alkoxylated alcohol
- And at least one lipophilic surfactant.
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Water phase composition requirement
- The water phase comprises:
- at least one hydrophilic surfactant
- water
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Post-formation amphiphile addition
- A “non-surfactant amphiphilic compound” is:
- “added to the composition after formation of said microemulsion or sub-micron emulsion”
- “miscible in said water phase”
This sequence element (“added after formation”) can matter both for literal infringement (process/sequence is part of the composition claim’s definition) and for claim construction arguments.
Dependent claim scope that tightens formulation space
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Claim 2 (ratio window)
Hydrophilic surfactant : lipophilic surfactant roughly 9:1 to 2:3.
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Claims 3-4 (oil phase with petrolatum and mineral oil)
Claim 3 narrows oil phase to mineral oil and lipophilic surfactants.
Claim 4 narrows further to a mixture of petrolatum + mineral oil + lipophilic surfactant.
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Claims 5-6 (specific amphiphilic solvents)
Amphiphilic compound is a water-miscible organic solvent:
- general class: alcohol or polyol
- specific embodiments: propylene glycol and phenoxy ethanol.
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Claims 7-9 (aggregated HLB number)
Surfactants have an “aggregated HLB number” in:
- 8.0–15.0 (Claim 7)
- 10–12 (Claim 8)
- 9.7–11.8 (Claim 9)
Method claim scope (Claim 10) tracks the composition, then converts to use
Claim 10 is a dermal treatment method that applies:
- an effective amount of the same O/W microemulsion/sub-micron emulsion composition
- to skin of a patient with a dermal condition
There is no limitation to specific indications; it is broad to “medical or cosmetic treatment of a dermal condition.”
Claim 11 repeats the surfactant ratio window.
How broad are the claims, and what are the key infringement “hooks”?
Broadest meaningful scope: architecture and component classes
The claims are broad because the oil-phase component list includes many categories, including:
- traditional oils (animal, vegetable, mineral)
- emollient-like systems (fatty acids, fats, esters)
- polymeric/functional classes (silane, siloxane)
- formulation adjuncts (alkoxylated alcohols)
- and a “halogen compound” bucket
Likewise, the water phase needs at least one hydrophilic surfactant and water, without a list of permitted surfactants.
Narrowing hooks that can reduce design-around risk but create factual and technical questions
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Desonide location constraint
- Literal infringement depends on whether desonide is in the water phase or both phases.
- If a competitor designs a system where desonide partitions predominantly into oil droplets with minimal water-phase presence, it may argue non-infringement.
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Post-formation addition of non-surfactant amphiphile
- The amphiphile is “added after formation.”
- This is a sequence limitation tied to how the formulation is prepared, not merely what ingredients are present.
- Even if the final composition is similar, process/sequence evidence can become central.
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Amphiphile identity constraints in dependent claims
- If a competitor uses a different amphiphilic solvent outside the claimed class (or outside the specific embodiments), they can potentially avoid dependent claims.
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HLB aggregation window
- If the competitor uses different surfactant systems yielding an aggregated HLB outside the range, it may avoid dependent claim protection.
Practical reading: how a formulation team would likely evaluate freedom-to-operate
A competitor seeking to avoid US 9,492,384 would typically target at least one of these three anchors:
- move the desonide predominantly to the oil phase (negate “water phase or both”)
- change formulation sequence so the amphiphilic compound is not “added after formation” as claimed
- change surfactant system and/or HLB characteristics out of the dependent windows (while still maintaining a functional microemulsion)
What adjacent claims and design-around opportunities exist within the same claim set?
Oil phase scope and sub-claim positioning
- Claims 3-4 create a narrower lane: mineral oil and optionally petrolatum.
- Claim 1 covers mineral oil and petrolatum only indirectly through the broader oil-phase list.
- In practice, an alternative formulation using vegetable oils, siloxanes, silanes, ester components, or alkoxylated alcohols could still fall within Claim 1 while avoiding Claims 3-4.
Amphiphile identity scope
- Claim 5 covers amphiphilic compounds broadly as water-miscible alcohols and polyols.
- Claim 6 narrows to propylene glycol and phenoxy ethanol.
- A competitor using a different water-miscible solvent (e.g., glycerol, sorbitol derivatives, certain glycols not named) may still fall under Claim 5 but could avoid the explicit embodiments of Claim 6 if claim interpretation requires exact identity.
Surfactant ratio and HLB windows as dependent “guardrails”
- Claim 2 restricts hydrophilic-to-lipophilic surfactant ratio.
- Claims 7-9 restrict aggregated HLB number ranges.
- These are classic dependent-claim levers for both enforcement selectivity and design-around.
How does US 9,492,384 compare with typical topical steroid microemulsion patents?
Typical industry claim patterns
Topical steroid microemulsion patents frequently claim:
- (i) an emulsion or microemulsion composition
- (ii) steroid active
- (iii) surfactant and solvent system
- (iv) sometimes particle size or droplet size language
- (v) optionally a preparation method
Distinctive features of US 9,492,384
The most distinctive elements in the provided claim set are:
- explicit requirement that desonide is in the water phase or both phases
- inclusion of a non-surfactant amphiphilic compound added after microemulsion formation and required miscibility in water phase
- a component list that directly includes silane and siloxane, expanding beyond standard oil/surfactant systems
What is the likely patent estate breadth around US 9,492,384 (based on the provided claims)?
Without the full family data, you cannot map the entire estate precisely, but the claim architecture implies the protection is targeted at:
- composition (O/W microemulsion / sub-micron emulsion containing desonide)
- method of use (dermal application to treat dermal condition)
- plus formulation sub-ranges (surfactant ratio, HLB, specific amphiphile solvents)
- and oil phase sub-ranges (mineral oil and petrolatum)
In enforcement, this setup typically creates layered protection:
- primary coverage at Claim 1 level
- narrower but often easier-to-prove dependent claim coverage at Claims 2-9 and 11
- method coverage under Claim 10 that can attach to any infringement of the composition if the dermal use element is satisfied
When does exclusivity end? What is the expiration timeline for US 9,492,384?
No expiration timeline can be calculated from the claim text alone. Determining the life of US 9,492,384 requires at minimum the patent’s issue date, filing date, and any PTA/terminal disclaimer. Without that information, an accurate exclusivity/expiration timeline cannot be produced.
Is US 9,492,384 likely to be relevant to generics or biosimilars of desonide?
This is a small-molecule topical steroid formulation patent. “Biosimilar risk” is not applicable.
For generic relevance, two legal realities matter:
- Generics must match active ingredient and formulation enough to qualify, but patents on formulation design can still block approval/launch of generic products even when API is generic.
- If a competitor’s generic matches desonide API but uses a different delivery system that does not meet the claim’s microemulsion architecture and sequence/phase requirements, infringement may be avoidable.
The practical risk hinges on whether a generic topical can be designed that:
- still qualifies for FDA approval
- but does not satisfy the specific claim limitations, especially:
- desonide-in-water-phase requirement
- post-formation addition of amphiphilic non-surfactant agent
- surfactant ratio/HLB windows (depending on claim asserted)
What formulations are protected by US 9,492,384? (Claim-to-formulation mapping)
Protected formulation “recipe logic” (Claim 1)
To fall within Claim 1, a product must satisfy:
- Desonide is placed in the water phase or both phases.
- O/W microemulsion/sub-micron emulsion structure exists.
- Oil phase contains:
- one or more component from the broad listed classes, and
- at least one lipophilic surfactant.
- Water phase contains:
- at least one hydrophilic surfactant and water.
- A water-miscible non-surfactant amphiphilic compound is incorporated after microemulsion/sub-micron formation and is miscible in the water phase.
Protected sub-types via dependent claims
- Oil phase including mineral oil and lipophilic surfactant (Claim 3)
- Oil phase including petrolatum + mineral oil + lipophilic surfactant (Claim 4)
- Amphiphilic compound = propylene glycol or phenoxy ethanol (Claim 6)
- Surfactant HLB aggregation within 8-15 / 10-12 / 9.7-11.8 (Claims 7-9)
- Hydrophilic-to-lipophilic surfactant ratio 9:1 to 2:3 (Claims 2 and 11)
Key patent-claim construction issues that affect enforceability (based on the claim language provided)
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What does “aggregated HLB number” mean in practice?
Dependent claims tie patentability and infringement to an HLB measurement concept. Litigation typically requires:
- selecting a calculation method
- showing how “aggregated” is determined for mixed surfactants
- verifying measurement under the accused formulation conditions
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How is “desonide is in said water phase or is in both said oil phase and said water phase” proven?
This is a phase-partition factual issue. Enforcement would likely need analytical evidence for:
- distribution between phases
- whether extraction/processing during testing collapses the microemulsion
- stability over storage
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Sequence limitation “added after formation”
If accused products use a single-pot or different order of addition, defendants may dispute whether the amphiphile was truly added after formation as required by Claim 1.
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“Non-surfactant amphiphilic compound” classification
If the amphiphilic compound in an accused formulation functions as a surfactant, it may not be “non-surfactant,” potentially avoiding Claim 1 depending on claim construction.
Key Takeaways
- US 9,492,384 protects a desonide O/W microemulsion or sub-micron emulsion with a specific phase location requirement: desonide is in the water phase or both phases.
- The claims are anchored by the post-formation addition of a non-surfactant amphiphilic, water-miscible compound that is miscible in the water phase.
- Dependent claims create additional narrowing lanes via:
- hydrophilic/lipophilic surfactant ratio
- petrolatum/mineral oil oil-phase selection
- propylene glycol and phenoxy ethanol
- aggregated HLB ranges
- Freedom-to-operate for a competitor would most efficiently evaluate three levers: desonide partitioning, sequence of amphiphile addition, and surfactant system/HLB/ratio alignment.
FAQs
1) What ingredients categories can satisfy the oil-phase component requirement in US 9,492,384?
The claim lists oil-phase candidates including animal/mineral/vegetable oils, silanes, siloxanes, esters, fatty acids, fats, halogen compounds, and alkoxylated alcohols, paired with at least one lipophilic surfactant.
2) Does US 9,492,384 require a specific droplet size or particle size?
The provided claims require an “O/W microemulsion or sub-micron emulsion,” but no numeric droplet size threshold is included in the text provided.
3) Can a formulation avoid infringement by putting desonide only in the oil phase?
The independent claim requires desonide be in the water phase or both phases. A design that keeps desonide effectively only in the oil phase targets that limitation.
4) Are propylene glycol and phenoxy ethanol the only amphiphilic solvents covered?
No. They are explicit embodiments in dependent Claim 6, while Claim 5 covers water-miscible alcohols and polyols more broadly.
5) Does US 9,492,384 protect only compositions or also methods?
It includes both composition coverage (Claim 1 and others) and a method-of-treatment claim (Claim 10) based on applying the claimed composition to skin of a patient with a dermal condition.
References
- Provided claim language for US 9,492,384 (user-supplied).
