Details for Patent: 8,460,641

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Which drugs does patent 8,460,641 protect, and when does it expire?

Patent 8,460,641 protects OLUX E and VERDESO and is included in two NDAs.

This patent has twenty-two patent family members in sixteen countries.

Summary for Patent: 8,460,641

Title:	Microemulsion process and composition
Abstract:	An oil-in-water microemulsion or sub-micron emulsion composition for dermal delivery of at least one pharmaceutically active ingredient, comprising: a first part including at least one occlusive agent and one or more lipophilic surfactants dispersed throughout a second part including water and at least one hydrophilic surfactant, and a non-surfactant amphiphilic type compound, pharmaceutically active ingredient, and water. It has been found that if a non-surfactant amphiphilic type compound is added together with the second part as would conventionally be the case, a microemulsion or sub-micron emulsion is not formed, by adding the so called third part, phase assembly occurs at a lower temperature than would be expected and moreover, this phase appears to assist in maintaining the microemulsion or sub-micron emulsion characteristics of the formulation during storage at normal temperatures.
Inventor(s):	Maria Graziella Larm, Ronald Harding, Michael Johnston, Albert Zorko Abram, Prema Vijayakumar, Phoebe Sun
Assignee:	Stiefel West Coast LLC
Application Number:	US11/216,668
Patent Claim Types: see list of patent claims	Use; Composition; Delivery;

United States Patent 8,460,641: Claim Scope, Exclusivity, Litigation Risk, and Topical Foam Patent Landscape

US Patent No. 8,460,641 protects aerosol foam and mousse formulations built around an oil-in-water microemulsion or sub-micron emulsion. The core combination requires a water-insoluble or sparingly water-soluble active ingredient, dispersed oil droplets, surfactant control, a propellant, and an amphiphilic compound added after emulsion formation. The strongest claim limitations are the formulation architecture, post-formation addition of the amphiphilic compound, surfactant ratio, and aerosol foam dosage form.

The patent is directed to a platform technology rather than one named drug. Its dependent claims identify corticosteroids, desonide, clobetasol, betamethasone, vitamin D analogues, and vitamin A analogues as representative active ingredients. The patent does not, based on the supplied claims, require a particular active ingredient, concentration, particle size, propellant, container, treatment indication, or brand.

What does US Patent 8,460,641 protect?

US 8,460,641 protects topical aerosol compositions and treatment methods using a specific emulsion-based delivery system. The independent claims divide into two composition groups and two method groups.

Claim group	Claim type	Principal subject matter
Claims 1-3, 5-8	Composition	Mineral oil or petrolatum-based oil-in-water microemulsion or sub-micron emulsion
Claim 4	Method	Dermal treatment using the claim 1 formulation
Claims 9, 12-16	Composition	Broader oil-phase class, including mineral, animal, vegetable, silicone, ester, fatty-acid and related materials
Claims 10-11	Composition	Narrower mineral oil or petrolatum embodiments
Claims 17-19	Method	Dermal treatment using the broader claim 9 formulation
Claims 20-21	Composition	Corticosteroid embodiments

The patent therefore has four independent claims:

• Claim 1: narrow composition claim.
• Claim 4: treatment method corresponding to claim 1.
• Claim 9: broader composition claim.
• Claim 17: treatment method corresponding to claim 9.

Claims 2, 5, 6, 13, 14 and 15 narrow the formulation by aggregated hydrophilic-lipophilic balance, or HLB. Claims 3, 16, 20 and 21 narrow the active ingredient. Claims 7, 8, 10, 11, 12, 18 and 19 narrow the solvent or oil phase.

What are the essential limitations of independent claim 1?

Claim 1 requires the following elements in combination:

1. A pharmaceutically active ingredient that is insoluble or sparingly soluble in water.
2. An oil-in-water microemulsion or sub-micron emulsion.
3. An oil phase dispersed throughout a water phase.
4. An oil phase containing:
   • mineral oil, petrolatum, or a mixture of the two; and
   • at least one lipophilic surfactant.
5. A water phase containing:
   • at least one hydrophilic surfactant; and
   • water.
6. A propellant.
7. A non-surfactant amphiphilic compound.
8. The amphiphilic compound is a water-miscible organic solvent selected from glycols, polyols, or mixtures.
9. The amphiphilic compound is added after formation of the emulsion.
10. The amphiphilic compound is miscible in the water phase.
11. The weight ratio of hydrophilic surfactant to lipophilic surfactant is approximately 9:1 to 2:3.
12. The formulation is dispensed as an aerosol foam or mousse.
13. The active ingredient is in the water phase or in both phases.

A product that omits one of these limitations may avoid literal infringement of claim 1. The principal design-around opportunities are the oil phase, order of addition, surfactant ratio, aerosol format, and location of the active ingredient.

How broad is independent claim 9 compared with claim 1?

Claim 9 is broader in its oil-phase definition but less specific in other respects.

Feature	Claim 1	Claim 9
Oil phase	Mineral oil, petrolatum, or mixtures	Broad list including animal, mineral and vegetable oils, silanes, siloxanes, esters, fatty acids, fats, halogen compounds and alkoxylated alcohols
Amphiphilic compound	Must be glycol, polyol or mixture	Defined only as a non-surfactant amphiphilic compound in the independent claim
Post-formation addition	Required	Required
Water-phase miscibility	Required	Required
Surfactant ratio	Approximately 9:1 to 2:3	Approximately 9:1 to 2:3
Aerosol foam or mousse	Required	Required
Active distribution	Water phase or both phases	Water phase or both phases
Propellant	Required	Required

Claim 9 reaches silicone-containing, ester-based, fatty-acid, vegetable-oil and other oil systems that do not fall within claim 1's mineral oil and petrolatum limitation. Claims 10-12 then recover narrower embodiments, including mineral oil, petrolatum, glycols and polyols.

For freedom-to-operate analysis, claim 9 is the principal broad composition claim. Claim 1 is more technically constrained but may be commercially important because mineral oil and petrolatum are common excipients in occlusive topical products.

What formulations are protected by the HLB claims?

Claims 2, 5, 6, 13, 14 and 15 establish nested HLB ranges:

Claim	Aggregated HLB range
2 and 13	8.0 to 15.0
5 and 14	10 to 12
6 and 15	9.7 to 11.8

The narrowest range, 9.7 to 11.8, is contained within the 10 to 12 range and the 8 to 15 range. A formulation within the narrow range would generally satisfy the broader HLB limitations as well, assuming the other elements are met.

The HLB limitations do not independently protect a surfactant system. They apply only when the formulation also contains the required emulsion, active ingredient, propellant, amphiphilic compound, surfactant ratio and aerosol delivery format.

A key technical issue is how “aggregated HLB number” is calculated. The patent specification and formulation records would control the methodology, including whether the value is weighted by surfactant mass, molecular proportion, or another formulation-specific method. A competitor cannot reliably assess the limitation from the trade name of a surfactant alone.

How does the patent treat propylene glycol and other solvents?

Claim 7 identifies propylene glycol as a specific non-surfactant amphiphilic compound. Claims 12 and 19 cover glycols, polyols and mixtures.

The claim language requires the compound to be added after formation of the microemulsion or sub-micron emulsion. This process limitation is commercially important because a finished product may contain propylene glycol but still fall outside the claim if the compound was introduced before the emulsion was formed, depending on how the manufacturing steps are construed and proven.

Potentially relevant compounds include:

• Propylene glycol.
• Polyethylene glycols.
• Other glycols.
• Glycerol and related polyols.
• Mixtures of glycols and polyols.

The record of manufacture, batch instructions, order of addition, mixing sequence and in-process testing would be central to proving or defending this limitation. A composition-only claim can create evidentiary problems when the claim includes a manufacturing step but the final product does not retain a unique chemical marker of that step.

Which active ingredients fall within the patent claims?

The independent claims are not limited to corticosteroids. They cover any pharmaceutically active ingredient that is insoluble or sparingly soluble in water, provided the remaining formulation limitations are met.

The dependent claims specifically identify:

• Corticosteroids.
• Desonide.
• Clobetasol.
• Betamethasone.
• Vitamin D analogues.
• Vitamin A analogues.

The claims do not expressly limit the formulation to dermatologic diseases. Claims 4 and 17 require medical or cosmetic treatment of a dermal condition, while the composition claims are not tied to a named indication.

The active ingredient may be in the aqueous phase or in both the aqueous and oil phases. The claim language therefore excludes a formulation in which the active exists exclusively in the oil phase, unless another claim construction treats the active as also present in the water phase.

What is the likely patent term and exclusivity timeline?

US 8,460,641 was issued on June 11, 2013. The patent's effective expiration cannot be determined from the claims alone because it depends on the earliest effective nonprovisional filing date, any terminal disclaimer, patent-term adjustment, patent-term extension and fee status recorded in the official patent file. The issue date by itself does not establish the expiration date.[1]

The relevant exclusivity events are:

Event	Date or status
US patent grant	June 11, 2013
Patent term basis	Generally 20 years from the earliest effective nonprovisional filing date
Patent-term adjustment	Must be checked in USPTO Patent Center
Patent-term extension under 35 U.S.C. § 156	No extension can be inferred from the supplied claims
Regulatory exclusivity	Product-specific; not established by this patent
Orange Book listing	Drug-specific and NDA-specific; not established by the patent number
Current enforceability	Requires current USPTO maintenance-fee and terminal-disclaimer records

A patent expiration date should not be assigned solely from the grant date. Patent families in this area may include continuations, divisionals or related applications with different claim scope and expiration consequences.

What is the Orange Book status of US 8,460,641?

US 8,460,641 is not itself an Orange Book entry. The FDA Orange Book lists patents submitted for approved drug products, not all patents that may cover topical formulation technology.[2]

An Orange Book listing would depend on:

• A specific approved drug.
• The NDA holder's patent submission.
• FDA acceptance of the patent information.
• The patent's relationship to the approved formulation, active ingredient or method of use.
• The listing category, such as drug substance, drug product or method of use.

Because the supplied claims do not identify a particular approved product or NDA, no product-specific Orange Book conclusion follows. A topical foam using the claimed technology might be associated with an Orange Book-listed patent, a non-listed formulation patent, or both.

What Paragraph IV challenges and generic-entry risks exist?

A Paragraph IV certification is available only in connection with an ANDA referencing an NDA product and a patent listed for that product. The existence of US 8,460,641 does not by itself establish that a Paragraph IV challenge has been filed.[3]

For a generic topical foam, the principal invalidity and noninfringement issues would likely include:

Issue	Potential argument
Anticipation	Earlier topical emulsions may disclose the same ingredients, ratios and aerosol format
Obviousness	Combining known microemulsions, glycols, surfactants and aerosol propellants may be argued as predictable
Claim construction	“Microemulsion,” “sub-micron emulsion,” “aggregated HLB” and “added after formation” may be disputed
Written description	Broad oil-phase and active-ingredient classes may be challenged if the specification does not support the full scope
Enablement	The challenger may argue that the full genus requires undue experimentation
Literal infringement	A product may omit the claimed oil phase, solvent class, HLB range, phase distribution or manufacturing sequence
Doctrine of equivalents	Risk remains where a design-around makes only a minor technical substitution

Topical products create a separate regulatory complexity. FDA may require comparative characterization of formulation, particle or droplet size, rheology, spray performance, foam properties, evaporation, delivery and local drug concentration, depending on the product and pathway.[4]

How strong is the patent estate for aerosol topical emulsions?

US 8,460,641 has meaningful claim breadth at the formulation-platform level, but its enforceability depends on several cumulative limitations.

Strengths

• Four independent claims cover compositions and treatment methods.
• Claim 9 reaches a wide group of oil-phase materials.
• The patent covers multiple insoluble active classes.
• The aerosol foam or mousse limitation maps to a commercially recognizable dosage form.
• The post-formation solvent step may distinguish ordinary premixed emulsions.
• HLB-dependent claims provide narrower fallback positions.

Vulnerabilities

• The claims require a specific combination of formulation and process characteristics.
• “Approximately” may create boundary disputes for the surfactant ratio.
• HLB calculations may be method-dependent.
• The active ingredient must be in the water phase or both phases.
• A non-aerosol cream, gel, lotion, ointment or pump foam may fall outside the claims.
• Products using only oil-solubilized active may avoid the claimed phase distribution.
• A formulation using a non-amphiphilic solvent or a different addition sequence may present a design-around.

The strongest enforcement position would likely involve a product whose documents show mineral oil or petrolatum, glycol addition after emulsion formation, a qualifying surfactant ratio, water-phase active, and aerosol foam dispensing.

What manufacturing and IP barriers affect generic launch?

A generic or follow-on developer must address two different barriers:

1. Patent infringement risk.
2. Demonstration of pharmaceutical equivalence or comparable performance.

Manufacturing records may expose infringement even where the final product is analytically similar. The relevant evidence may include:

• Master batch records.
• Order-of-addition instructions.
• Surfactant calculations.
• HLB worksheets.
• Droplet-size specifications.
• Propellant filling records.
• Microscopy or particle-size testing.
• Phase-distribution studies.
• Solvent assay and water-content data.

A product may avoid one claim while still falling within another. For example, replacing mineral oil with a silicone oil may avoid claim 1 but potentially implicate claim 9. Moving propylene glycol to the initial aqueous phase may avoid the post-formation limitation, but the result depends on the manufacturing record and claim construction.

How does US 8,460,641 compare with competing topical patent strategies?

Patent strategy	Typical protected feature	Relationship to US 8,460,641
Active-ingredient patent	New chemical entity or salt	8,460,641 is not limited to one active
Formulation patent	Vehicle, emulsion, solvent or surfactant system	Directly overlaps in subject matter
Method-of-use patent	Treatment of a named disease	8,460,641 uses broader dermal-condition language
Device patent	Canister, actuator or dispensing system	8,460,641 focuses on formulation and aerosol form
Manufacturing patent	Mixing, emulsification or filling process	The post-formation addition limitation creates process relevance
Product-by-process patent	Product defined by how it is made	The patent includes process language within composition claims

The patent is therefore most relevant to topical foam companies, dermatology product developers, generic manufacturers and licensors using sub-micron emulsions for poorly water-soluble actives.

What litigation and settlement issues should be reviewed?

The supplied information does not establish a particular infringement action, Paragraph IV notice, settlement agreement or license involving US 8,460,641. A complete litigation assessment must distinguish:

• Direct infringement actions.
• ANDA litigation under the Hatch-Waxman Act.
• Declaratory-judgment suits.
• Patent-term or maintenance-fee disputes.
• License agreements covering the formulation platform.
• Settlement agreements restricting generic launch.
• Assignments and security interests affecting ownership.

Ownership and standing should be verified against USPTO assignment records. Litigation status should be checked through PACER and court dockets, while regulatory patent listings should be checked through FDA's Orange Book database.[2,5]

Key Takeaways

• US 8,460,641 covers oil-in-water microemulsion and sub-micron emulsion aerosol foams and mousses for poorly water-soluble dermal actives.
• Claims 1 and 4 are narrower because they require mineral oil or petrolatum.
• Claims 9 and 17 provide broader oil-phase coverage, including silicone, ester, fatty-acid, vegetable-oil and related systems.
• The most important claim limitations are the post-formation addition of the amphiphilic solvent, surfactant ratio, aerosol format and active distribution.
• Dependent claims focus on HLB ranges of 8-15, 10-12 and 9.7-11.8.
• Corticosteroids, desonide, clobetasol, betamethasone, vitamin D analogues and vitamin A analogues are expressly identified.
• The patent number alone does not establish Orange Book listing, Paragraph IV litigation, current enforceability or a precise expiration date.
• A generic developer's main design-around options are changing the oil phase, addition sequence, solvent class, surfactant ratio, active phase distribution or delivery format.

FAQs About US Patent 8,460,641

Does US 8,460,641 cover clobetasol foam?

It can cover a clobetasol foam if the product satisfies the applicable emulsion, surfactant, solvent, propellant, phase-distribution and aerosol limitations. The patent does not automatically cover every clobetasol foam.

Can a cream infringe US 8,460,641?

A conventional non-aerosol cream generally would not satisfy the express aerosol foam or mousse limitation. A product marketed as a cream but dispensed as an aerosol mousse requires a more detailed claim analysis.

Does using propylene glycol automatically create infringement?

No. Propylene glycol is only one claim element. The claims also require the specified emulsion, surfactants, ratio, phase distribution, propellant and post-formation addition.

Can a silicone-oil foam avoid the patent?

It may avoid claim 1's mineral oil or petrolatum limitation, but claim 9 expressly includes silanes and siloxanes within the broader oil-phase category. The remaining limitations must also be assessed.

Is a patent license required to launch a topical foam using this technology?

The need for a license depends on the patent's enforceability, expiration, ownership, claim construction, product formulation and applicable jurisdiction. The patent number alone does not establish a licensing obligation.

References

1. United States Patent and Trademark Office. (2013). U.S. Patent No. 8,460,641, Microemulsions and sub-micron emulsions for topical delivery of active agents.
2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
3. U.S. Food and Drug Administration. (2024). Abbreviated new drug application regulations and patent certifications.
4. U.S. Food and Drug Administration. (2016). Draft guidance for industry: Topical dermatologic drug products submitted for ANDAs.
5. United States Patent and Trademark Office. (2024). Patent Center and patent assignment search.

Drugs Protected by US Patent 8,460,641

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Quagen	OLUX E	clobetasol propionate	AEROSOL, FOAM;TOPICAL	022013-001	Jan 12, 2007		DISCN	Yes	No	8,460,641		Y			TREATMENT OF CORTICOSTEROID-RESPONSIVE DERMATOSES
Genus	VERDESO	desonide	AEROSOL, FOAM;TOPICAL	021978-001	Sep 19, 2006		DISCN	Yes	No	8,460,641		Y			TREATMENT OF ATOPIC DERMATITIS

International Family Members for US Patent 8,460,641

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	051197
Australia	2005279704
Brazil	PI0514806
Canada	2578594
Canada	2756674