US Patent 8,232,264: Claim Scope, Formulation Coverage, Exclusivity and Generic Risk

US Patent 8,232,264 protects topical corticosteroid compositions built around unusually high concentrations of penetration enhancers. Its central limitation is a composition-level ratio: penetration enhancers must account for at least approximately 90% of the combined amount of penetration enhancers, solvents and emulsifiers. The patent also reaches formulations containing fluocinonide or fluocinolone acetonide, including high-propylene-glycol compositions.

The strongest commercial risk is concentrated in formulations that use propylene glycol or dimethyl isosorbide as a major vehicle component, contain at least one additional listed penetration enhancer, and use the specified solvent/emulsifier system. The patent does not broadly cover every topical corticosteroid product or every fluocinonide formulation.

What does US Patent 8,232,264 protect?

The patent contains five independent composition claims: claims 1, 15, 27, 29 and 43. They divide into two principal formulation architectures.

Claim group	Core structure	Key additional limitation
Claim 1	Corticosteroid; at least two listed penetration enhancers; listed solvents or emulsifiers	Enhancer ratio of at least about 0.90
Claim 15	Claim 1-type composition plus listed non-solvent/emulsifier ingredients	Purified water is required
Claim 27	Propylene glycol plus a second listed enhancer; listed solvents/emulsifiers; non-solvent/emulsifier ingredients	Propylene glycol is at least 66.8% of the composition
Claim 29	Corticosteroid; dimethyl isosorbide plus a second listed enhancer; listed solvents or emulsifiers	Enhancer ratio of at least about 0.90
Claim 43	Claim 29-type composition plus listed non-solvent/emulsifier ingredients	Purified water is required

The claims are composition claims rather than method-of-treatment claims. They do not expressly require a particular disease, body site, dosing schedule, package, manufacturing process or clinical result.

The patent’s coverage therefore turns on the formulation ingredients and their relative quantities, not solely on the identity of the active corticosteroid.

How does the penetration-enhancer ratio work?

The ratio is the principal quantitative limitation. In practical terms:

[ \text{Ratio} = \frac{\text{penetration enhancers}}{\text{penetration enhancers}+\text{solvents and emulsifiers}} ]

The claims require a ratio of at least about 0.90. Claims 9, 23, 37 and 51 raise the threshold to at least about 0.95.

If the solvent/emulsifier pool equals 5% of the formulation, the penetration-enhancer pool must be approximately 45% or more to reach a 0.90 ratio. If the solvent/emulsifier pool equals 4%, the enhancer pool must be approximately 36% or more.

This limitation materially narrows the claims. A conventional cream containing a small amount of propylene glycol as a humectant or cosolvent may fall outside the claims even if it contains a corticosteroid and another listed ingredient.

The phrase "at least about" creates a potential claim-construction issue around measurement precision, formulation tolerances and analytical variability. A formulation near 0.90 or 0.95 would require careful review of the patent specification, prosecution history and product composition.

Which ingredients are covered by the patent?

Penetration enhancers

The claimed penetration-enhancer group contains:

Diisopropyl adipate
Dimethyl isosorbide
Propylene glycol
1,2,6-hexanetriol
Benzyl alcohol

Claims 1 and 29 require two or more enhancers from this group. Claim 27 requires propylene glycol as the first enhancer and one of the other four listed materials as the second enhancer.

The claim language does not appear to cover a formulation using only propylene glycol. It requires at least two penetration enhancers.

Solvents and emulsifiers

The listed solvent/emulsifier category includes dehydrated alcohol, 95% alcohol, ethoxydiglycol, propylene carbonate, oleyl alcohol, sodium lauryl sulfate, polysorbate 60, sorbitan derivatives, steareth compounds, PEG materials, potassium hydroxide solutions and other named substances.

This is a closed group for the express claim elements. A formulation using a functionally similar but chemically different solvent may avoid literal infringement of this limitation, although the doctrine of equivalents could remain relevant depending on the facts.

Non-solvent/emulsifier ingredients

Claims 10, 11, 15, 27, 38, 39 and 43 add a second ingredient category that includes:

Purified water
Petrolatum and white petrolatum
Mineral oil
Stearyl alcohol
Glyceryl stearate and PEG-100 stearate
Carbopol 980
Cyclomethicone
Hydroxyethyl cellulose
Hydroxypropyl cellulose
Isopropyl myristate
Parabens
Oleic acid
White wax

Claims 15, 27 and 43 require purified water. Claims 1 and 29 do not require water unless a dependent claim or the commercial formulation adds it.

What corticosteroids are covered?

Claims 2 and 16, and claims 30 and 44, specify fluorinated corticosteroids. Claims 3, 17, 31 and 45 expressly identify fluocinonide. Claims 4, 18, 32 and 46 expressly identify fluocinolone acetonide.

The independent claims use the broader term "one or more corticosteroids." The dependent claims provide narrower, expressly recited embodiments. The broad independent claims can potentially reach corticosteroids other than fluocinonide and fluocinolone acetonide if the remaining formulation limitations are met.

The claims cover several concentration ranges:

Claim limitation	Concentration
Claims 5, 19, 33 and 47	About 0.10% corticosteroid
Claims 6, 20, 34 and 48	At least about 0.50%
Claims 7, 21, 35 and 49	At least about 0.25%

These dependent claims overlap in part. A formulation containing 0.50% active would also satisfy an "at least about 0.25%" limitation, subject to the other claim elements.

What formulations are most exposed?

The highest-risk formulation profile is:

A topical corticosteroid;
Propylene glycol plus at least one additional listed penetration enhancer;
Propylene glycol representing at least 66.8% of the entire composition;
A listed solvent or emulsifier;
Purified water and one or more listed non-solvent/emulsifier ingredients; and
A penetration-enhancer-to-solvent/emulsifier ratio of at least 0.90.

Claims 27 and 28 are particularly narrow but commercially important. They cover propylene-glycol-heavy products in the 66.8% to 74.9% range.

A second exposed profile uses dimethyl isosorbide as the required first penetration enhancer and combines it with diisopropyl adipate, propylene glycol, 1,2,6-hexanetriol or benzyl alcohol. Claims 29 through 43 cover this architecture.

A product may avoid the most specific claims by:

Using only one listed penetration enhancer;
Keeping propylene glycol below 66.8% of the total composition;
Substituting a non-listed solvent or emulsifier;
Reducing the enhancer ratio below 0.90;
Omitting purified water where water is required; or
Using a formulation outside the named non-solvent/emulsifier lists.

These design-around routes must be evaluated against the broader independent claims and potential equivalents.

How broad are the independent claims?

Claim 1

Claim 1 is the broadest principal claim. It requires two or more listed penetration enhancers, a corticosteroid and at least one listed solvent or emulsifier. It does not require purified water or the listed non-solvent/emulsifier category.

Its practical reach is constrained by the 0.90 ratio and by the closed ingredient lists.

Claim 15

Claim 15 adds purified water and one or more non-solvent/emulsifier ingredients. It is narrower than claim 1 but more closely aligned with a conventional semisolid topical product.

Claim 27

Claim 27 is the most quantitatively specific claim. It requires propylene glycol at 66.8% or more of the total composition. Claim 28 limits the range to 66.8% through 74.9%.

Claim 29

Claim 29 protects a dimethyl-isosorbide-centered alternative. Unlike claim 27, it does not require propylene glycol. It requires dimethyl isosorbide and a second enhancer from the specified list.

Claim 43

Claim 43 adds purified water and non-solvent/emulsifier ingredients to the dimethyl-isosorbide architecture. It is narrower than claim 29.

The repeated dependent claims create layered protection around the same formulation concepts. They do not materially expand the patent beyond the listed chemical classes, concentrations and ratio limitations.

Does the patent cover methods of use or manufacturing processes?

No express method-of-use claims appear in the supplied claim set. The patent does not claim treatment of psoriasis, eczema, dermatitis or another named condition. It also does not claim a manufacturing sequence, mixing temperature, particle-size requirement, packaging system or process control.

A manufacturer could still face infringement based on making, using, selling or importing a covered composition under 35 U.S.C. § 271. A generic applicant could face a Hatch-Waxman infringement action if its ANDA product and certification create the statutory basis for litigation under 35 U.S.C. § 271(e)(2).

What is the Orange Book status of US Patent 8,232,264?

The patent number alone does not establish Orange Book listing status. Orange Book relevance depends on whether the patent was submitted for a specific approved drug application and accepted by FDA as a patent claiming the drug substance, drug product or approved method of use.

US Patent 8,232,264 is a formulation patent on the supplied claim language. It is not a compound patent covering the corticosteroid molecule itself. If listed for an approved topical corticosteroid product, its practical effect would primarily concern the listed formulation rather than every generic product containing the same active ingredient.

FDA’s Orange Book identifies patents and exclusivity associated with approved products, while the patent’s enforceability and expiration depend on the patent file, maintenance status, terminal disclaimers, patent-term adjustment and any post-grant proceedings.[2][3]

When does US Patent 8,232,264 lose exclusivity?

The patent issued on July 31, 2012.[1] Its ordinary expiration date cannot be determined from the claim text alone because patent term is generally measured from the earliest effective nonprovisional filing date, not from the issue date. Patent-term adjustment, terminal disclaimers and any applicable extension must also be considered.

The relevant legal framework is:

Issue	Relevance
Patent term	Generally 20 years from the earliest effective nonprovisional filing date
Patent-term adjustment	May extend the term for qualifying USPTO delay
Terminal disclaimer	May shorten the term or tie it to another patent
Maintenance fees	Nonpayment can cause expiration before the nominal term
PTE	Usually more relevant to approved drug patents, but must be checked separately
Post-grant proceedings	May cancel or amend claims

A definitive expiration-date opinion requires the patent’s priority chain, continuity data, terminal-disclaimer records, maintenance-fee history and USPTO term calculation.

Are there Paragraph IV challenges or generic-launch risks?

The relevant generic risk is formulation-specific. A generic applicant could pursue several paths:

Launch path	Risk profile
Same or substantially identical high-PG formulation	High risk under claims 27 and 28
Dimethyl-isosorbide formulation using a second listed enhancer	Potential risk under claims 29 and 43
Conventional low-PG cream	Lower literal risk if the 0.90 ratio is not met
Formulation with one enhancer only	Potential design-around of the two-enhancer requirement
Formulation using non-listed vehicle ingredients	May avoid literal ingredient limitations
ANDA with Paragraph III certification	Launch follows patent expiration or delisting
ANDA with Paragraph IV certification	May trigger patent litigation and a 30-month stay under applicable FDA rules

The supplied claim set does not identify a Paragraph IV filing, ANDA applicant, lawsuit, settlement or launch date. Those events cannot be established from the claims themselves. A complete freedom-to-operate assessment must also review the patent family and related formulation patents.

How strong is the patent estate?

The estate appears technically focused rather than molecule-wide. Its strengths are:

Multiple independent claim architectures;
Explicit coverage of fluocinonide and fluocinolone acetonide;
Protection of high-propylene-glycol formulations;
Separate dimethyl-isosorbide coverage;
Ratio limitations that may map directly to commercial formulations;
Dependent claims covering water, semisolid excipients and corticosteroid concentrations.

Its vulnerabilities are:

Closed lists of penetration enhancers and vehicle ingredients;
A demanding 0.90 or 0.95 ratio;
Dependence on exact formulation composition;
Possible design-around through alternative solvents, enhancers or vehicle systems;
Potential written-description, enablement or indefiniteness issues involving large ingredient lists and "about" ranges;
Lack of method-of-use and manufacturing claims in the supplied claim set.

The commercial strength therefore depends heavily on whether an approved product’s actual composition falls inside the claimed ratio and ingredient combinations. A label alone may not disclose enough information to resolve that question.

What is the competitive patent landscape?

The relevant competitive landscape has four layers:

Active-ingredient patents, which are generally weak for older corticosteroids because fluocinonide and fluocinolone acetonide are established molecules.
Formulation patents, including US 8,232,264 and related family members.
Method-of-use patents, which may cover treatment of particular dermatological conditions or patient populations.
Regulatory exclusivities, including any drug-product exclusivity associated with the approved topical product.

For generic competition, formulation patents are the most relevant layer when the active ingredient is already off-patent. A generic developer can often reduce risk by using a different vehicle system, but topical bioequivalence, local delivery and clinical endpoint requirements can make formulation changes commercially and regulatorily significant.

Key Takeaways

US Patent 8,232,264 is a formulation patent focused on high-enhancer topical corticosteroid compositions.
The central limitation is an enhancer-to-solvent/emulsifier ratio of at least about 0.90, with some dependent claims requiring at least about 0.95.
The patent expressly covers fluocinonide and fluocinolone acetonide embodiments.
Claims 27 and 28 target formulations containing 66.8% to 74.9% propylene glycol.
Claims 29 and 43 target dimethyl-isosorbide formulations combined with a second listed penetration enhancer.
The claims do not expressly cover methods of use or manufacturing processes.
A conventional low-propylene-glycol corticosteroid cream may avoid literal infringement if it does not satisfy the two-enhancer and ratio limitations.
Orange Book listing, current ownership, expiration, litigation and settlement status require review of the patent and FDA records beyond the supplied claim text.

FAQs

Can a fluocinonide cream infringe US Patent 8,232,264 without containing dimethyl isosorbide?

Yes. Claims 1 and 27 can cover formulations using propylene glycol with another listed penetration enhancer. Dimethyl isosorbide is required only for the claim 29 and claim 43 branches.

Does 0.10% fluocinonide automatically fall within the patent?

No. The active concentration is only one limitation. The formulation must also satisfy the required enhancer count, ingredient lists, ratio and, for certain claims, purified-water and propylene-glycol requirements.

Is propylene glycol alone enough to satisfy the penetration-enhancer limitation?

No. The principal claims require two or more penetration enhancers. Propylene glycol alone would not satisfy that element.

Can changing the trade name of an excipient avoid infringement?

No. The chemical identity and claim classification matter, not the supplier’s trade name. A different trade name for the same chemical may remain within the claim.

Does a patent expiration automatically permit FDA approval of a generic topical product?

No. FDA approval also requires compliance with the applicable ANDA or other regulatory pathway, including product quality, sameness or bioequivalence requirements and any remaining listed patents or regulatory exclusivities.

References

United States Patent and Trademark Office. (2012). U.S. Patent No. 8,232,264, issued July 31, 2012.
U.S. Food and Drug Administration. (2025). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (n.d.). Drugs@FDA: FDA-approved drugs.
United States Code. (2024). 35 U.S.C. §§ 154, 271 and 282.
United States Patent and Trademark Office. (2024). Manual of Patent Examining Procedure, §§ 2111 and 2111.03.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2002360589	⤷ Start Trial
Brazil	0215254	⤷ Start Trial
Canada	2471041	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,232,264

Summary for Patent: 8,232,264