United States Patent 7,141,237: Claim Scope, Expiration, Orange Book Status and Generic Risk

U.S. Patent No. 7,141,237 covers clindamycin phosphate topical aerosol foams that use a specific alcohol-water fatty-alcohol-surfactant vehicle, a limited propellant concentration, a base, and a temperature-sensitive quick-breaking foam profile. The patent is directed to formulation architecture, not clindamycin phosphate itself or the general treatment of acne.

The patent’s enforceable life has ended. Its earliest priority is in 2000, and the 20-year patent term, including any applicable patent-term adjustment, ended no later than 2023. The patent therefore does not present a current U.S. blocking patent risk for a properly designed generic formulation. Its technical disclosure remains relevant because later products may have been developed around its foam-system limitations.

What does U.S. Patent 7,141,237 protect?

The patent protects a pressurized topical composition containing five principal elements:

Clindamycin phosphate, at up to 15% by weight.
A quick-breaking foaming agent representing approximately 83% to 97.9% by weight.
A C1-C6 alcohol, such as ethanol.
A C14-C22 fatty alcohol, such as cetyl alcohol or stearyl alcohol.
Water, surfactant, base and aerosol propellant.

The composition must form a quick-breaking, temperature-sensitive foam after discharge from the pressurized container.

The independent claims are composition claims. Claims 1, 28, 31, 32 and 33 do not require a particular method of treatment, patient population, dosage regimen or acne severity. Claim 28 adds treatment of acne. Claim 32 adds treatment of a bacteria-mediated disease.

Independent-claim structure

Claim	Principal subject matter	Distinguishing limitation
1	Pressurized topical clindamycin composition	Alcohol, fatty alcohol, water, surfactant, base and propellant; quick-breaking temperature-sensitive foam
28	Acne-treatment composition	Same formulation framework with acne treatment language
31	Pressurized topical composition	Expressly identifies the C1-C6 alcohol as methanol, ethanol, propanol, butanol or a mixture
32	Bacteria-mediated disease composition	Surfactant stated as 0% to 10%
33	Pressurized topical composition	Propellant maximum determined by miscibility sufficient to form a homogeneous solution

The use of “comprising” makes the claims open-ended. A competing product can contain additional excipients and still fall within the literal scope if all required elements are present.

How broad is claim 1 of U.S. Patent 7,141,237?

Claim 1 is broad in excipient identity but narrow in formulation structure. A product would generally need to satisfy each of the following limitations:

Claim element	Scope
Dosage form	Composition in a pressurized container
Active ingredient	Clindamycin phosphate, up to 15% w/w
Foaming system	83% to 97.9% w/w quick-breaking foaming agent
Short-chain alcohol	C1-C6 alcohol
Long-chain alcohol	C14-C22 alcohol
Aqueous phase	Water
Surfactant	Required by claim 1
Base	Required by claim 1, although the claim does not initially define its identity
Propellant	2% to 7% w/w
Propellant class	Hydrocarbon, chlorofluorocarbon, dimethyl ether, hydrofluorocarbon or mixture
Performance	Quick-breaking temperature-sensitive foam after release

The key limitation is the combination of composition and physical performance. A clindamycin foam that contains ethanol and water may avoid the claim if it lacks the specified fatty alcohol, surfactant, base, propellant range or temperature-sensitive quick-breaking behavior.

The claim does not require:

A 1% clindamycin phosphate concentration.
A particular container valve or actuator.
A particular aerosol can material.
A particular particle size.
A specific foam density.
A specific administration frequency.
A branded product.
Treatment of acne.

Which dependent claims define the narrowest formulation features?

Claims 2 through 27 and 29 through 35 narrow the vehicle, alcohol-water ratio, surfactant, emollient, pH, fatty-alcohol blend and base.

Alcohol-water ratio

The claims contain internally inconsistent ratio limitations:

Claims 2 through 4 recite a C1-C6 alcohol-to-water ratio of approximately 1:7 to 1:16.
Claim 6 recites approximately 1.7:1.
Claim 29 recites approximately 1.5:1 to 1:16.
Claim 30 recites approximately 1.6:1.

These ratios cannot all represent the same directional range if read literally as alcohol divided by water. Claims 6 and 30 appear inconsistent with claims 2 through 4 and may reflect drafting or transcription errors in the claim set. The original certified patent text, prosecution history and any corrected patent document control the legal interpretation.

Surfactant

Claims 7 through 9 require or narrow the surfactant to:

0.1% to 10% w/w;
an ethoxylated nonionic or ionic surfactant; or
a polysorbate.

Claim 32 recites surfactant at 0% to 10% w/w, which conflicts with claim 1’s express inclusion of a surfactant in the foaming agent. That inconsistency limits confidence in treating claim 32 as a clean, independent formulation position without reviewing the issued patent and prosecution record.

Fatty alcohol

Claims 17 through 22 narrow the long-chain alcohol to:

1% to 5% w/w;
C14-C20 alcohols;
cetyl alcohol, stearyl alcohol or a mixture;
a cetyl-to-stearyl ratio of 60:40 to 80:20;
approximately 70:30 cetyl alcohol to stearyl alcohol.

This is one of the most commercially significant narrowing features. A generic formulation using a different foam stabilizer or a fatty alcohol outside the claimed carbon range would have a stronger design-around position.

Water and pH

Claims 23 and 24 specify:

up to 90% w/w water; or
approximately 30% to 40% w/w water.

Claims 25 and 26 specify:

pH 4.0 to 9.0; or
pH 4.0 to 6.5.

These limitations would usually be assessed against the finished bulk formulation before filling, unless the specification or prosecution history supports another measurement point.

Base

Claims 34 and 35 narrow the base to:

bicarbonate;
carbonate;
alkali hydroxide;
alkaline-earth metal hydroxide;
transition-metal hydroxide; or
potassium hydroxide specifically.

Claim 1 requires “a base” but does not itself restrict the base to these categories. Claim 34 is therefore important for narrowing but does not necessarily define the entire scope of the base limitation in claim 1.

What formulation is most closely associated with the patent?

The commercial formulation concept associated with the patent is a 1% clindamycin phosphate aerosol foam using an ethanol-water vehicle, fatty alcohols, surfactant, base and hydrocarbon propellant. The formulation is designed to remain in a pressurized container and break rapidly after application to the skin, with temperature sensitivity supporting spreading and evaporation.

The claimed percentages are broad enough to cover more than one commercial recipe. A specific product cannot be conclusively mapped to every claim without its quantitative inactive-ingredient composition, manufacturing records and product-specific regulatory filings.

Technical claim chart

Technical feature	Commercial relevance	Design-around opportunity
Clindamycin phosphate	Defines the active drug form	Use another active or salt, subject to regulatory equivalence
Ethanol or other C1-C6 alcohol	Supports solvent system and foam break	Substitute another solvent or change alcohol-water ratio
Cetyl/stearyl alcohol	Stabilizes foam structure	Use another fatty alcohol, polymer or surfactant system
Water	Supports aqueous-alcoholic vehicle	Use a substantially nonaqueous system
Surfactant	Supports emulsion and foam formation	Use a different stabilizing architecture
2%-7% propellant	Enables aerosol delivery	Use a non-aerosol pump, bag-on-valve or alternative delivery system
Quick-breaking foam	Supports topical spreading	Use a gel, cream, solution or persistent foam
Temperature sensitivity	Links behavior to skin temperature	Use a non-temperature-sensitive product

When did U.S. Patent 7,141,237 expire?

The patent is expired in the United States.

Event	Date or period
Earliest priority period	2000
U.S. filing period	Approximately 2001
Patent grant	November 28, 2006
Standard 20-year term	Approximately 2021, measured from the relevant nonprovisional filing
Possible patent-term adjustment	Could extend the term beyond the base 20-year date
Latest practical term endpoint	No later than 2023 based on the applicable term and adjustment records
Current status	Expired; no current enforcement term

Patent expiration is determined from the earliest effective nonprovisional filing date, applicable priority claims, patent-term adjustment, patent-term extension and any terminal disclaimer. The grant date is not the expiration date. The USPTO Patent Center and maintenance-fee records are the controlling sources for the precise term calculation. [1]

What was the Orange Book status of clindamycin phosphate foam?

Clindamycin phosphate foam products, including Evoclin, were approved through the FDA’s new-drug application system for topical acne treatment. The Orange Book may identify patents associated with the listed drug and may have recorded exclusivity or patent information during the product’s commercial life. Orange Book listing does not extend an expired patent and does not independently create market exclusivity. [2]

The regulatory issues are separate from the patent issues:

A patent can be expired while the NDA remains listed.
A product can have no current market exclusivity even if historical Orange Book patents remain visible.
A generic applicant can challenge listed patents through a Paragraph IV certification.
A Paragraph IV certification against an expired patent does not create a 30-month stay for that patent.
FDA approval still depends on the applicable ANDA requirements, including pharmaceutical equivalence, bioequivalence and quality controls.

FDA pathway

For an immediate-release topical aerosol foam, the regulatory pathway generally involves an ANDA if the reference product and dosage form are eligible for generic approval. The applicant must address the active ingredient, strength, dosage form, route of administration, inactive ingredients and comparative performance requirements applicable to the product.

For topical semisolid or foam products, formulation sameness and performance can be more difficult than for a conventional oral solid. Foam expansion, break time, discharge characteristics, density, viscosity, droplet or particle distribution and container-closure performance can affect product development even after patent expiration.

Were Paragraph IV challenges likely to affect this patent?

A Paragraph IV challenge would have been relevant while the patent was unexpired and listed against the reference product. The principal potential arguments would have involved:

Noninfringement through a different propellant or foam system.
Noninfringement through exclusion of the claimed fatty alcohol.
Noninfringement through a non-temperature-sensitive or non-quick-breaking formulation.
Invalidity based on anticipation or obviousness over earlier aerosol foam, clindamycin, dermatological vehicle and cosmetic foam references.
Indefiniteness or written-description arguments directed to the functional foam limitations and inconsistent ratio language.
Lack of enablement across the breadth of the alcohol, surfactant, propellant and base classes.

The patent is now expired, so a new Paragraph IV challenge has little practical value against this patent itself. Historical litigation or settlement activity would still matter for understanding generic-entry timing and the commercial strength of the formulation technology.

Which companies challenged or commercialized clindamycin phosphate foam?

The principal branded product associated with this technology was Evoclin clindamycin phosphate foam, originally developed and commercialized within the Connetics dermatology business. Connetics was acquired by Stiefel Laboratories, and Stiefel was later acquired by GlaxoSmithKline. Corporate ownership and product commercialization changed over time. Those transactions should not be characterized as direct assignments or licenses of U.S. Patent 7,141,237 without reviewing the recorded assignment and transaction documents.

Generic clindamycin phosphate foam products have entered or been pursued after the relevant patent and regulatory barriers weakened. The competitive field includes:

Branded topical clindamycin products.
Generic clindamycin phosphate solutions, gels, lotions and pledgets.
Generic or authorized-generic foam products.
Combination acne products containing clindamycin and benzoyl peroxide.
Non-clindamycin acne treatments, including retinoids, benzoyl peroxide and topical antibiotics.

The patent did not cover all clindamycin dosage forms. A generic gel, solution or lotion would generally not satisfy the pressurized-container and foam limitations.

How strong is the patent estate for clindamycin phosphate foam?

The patent estate was technically meaningful during its term but was not a composition-of-matter estate for clindamycin phosphate. Its strength depended on the ability to demonstrate that a competing aerosol foam contained the required vehicle and physical properties.

Strength assessment

Issue	Assessment
Active ingredient exclusivity	Weak; clindamycin phosphate was known
Dosage-form coverage	Stronger; claims focus on pressurized foam delivery
Vehicle coverage	Moderate to strong where ethanol, fatty alcohol, water and surfactant are combined
Functional limitations	Potentially important but fact-intensive
Numerical ranges	Useful for narrowing, but vulnerable to design-around
Claim consistency	Reduced strength because of conflicting alcohol-water and surfactant language
Manufacturing barriers	Moderate; aerosol filling and foam-performance controls can be difficult
Current blocking value	None because the patent has expired

The patent’s commercial value came from the combination of formulation know-how and delivery performance. The patent alone did not prevent development of nonfoam clindamycin products or foam products using materially different excipient systems.

What patent litigation and settlement issues are relevant?

A complete litigation conclusion requires a docket-specific review of district-court filings, Federal Circuit decisions, FDA Paragraph IV notices and settlement agreements. The claim set alone does not establish whether a particular generic applicant litigated, settled or launched at risk.

For business analysis, the relevant litigation questions are:

Whether the reference-product sponsor listed 7,141,237 in the Orange Book.
Whether an ANDA applicant certified Paragraph IV.
Whether the patent was still unexpired when the notice was served.
Whether a 30-month stay applied.
Whether the parties entered a delayed-entry or license settlement.
Whether the generic product launched after patent expiry or before expiry under a license.
Whether any later patent covered the commercial foam, container, method of treatment or manufacturing process.

Because 7,141,237 is expired, a current generic entrant does not face damages exposure for post-expiration manufacture or sale based solely on this patent. Pre-expiration conduct would require a separate historical analysis.

What manufacturing and intellectual-property barriers remain?

Patent expiration does not eliminate technical barriers. A commercially viable clindamycin aerosol foam must address:

Propellant compatibility with the drug and excipients.
Homogeneity during storage and use.
Valve and actuator performance.
Corrosion and container-closure compatibility.
Foam break time at skin temperature.
Microbiological quality and preservative performance.
Ethanol evaporation and concentration drift.
Batch-to-batch foam density.
Filling accuracy and pressure control.
Stability under elevated temperature and transport conditions.

These factors can create regulatory and manufacturing advantages even without patent protection. They are not substitutes for an enforceable patent, but they can delay entry and increase development cost.

How does U.S. Patent 7,141,237 compare with other clindamycin patents?

Patent category	Subject matter	Relevance to 7,141,237
Compound patents	Clindamycin or related lincosamides	Generally unrelated; clindamycin was already known
Salt or formulation patents	Clindamycin phosphate compositions	May overlap in active form but not necessarily in aerosol foam
Topical vehicle patents	Alcohol, water, emulsion or foam systems	Potential prior art and design-around references
Aerosol patents	Pressurized foam delivery	Closest technical category
Method-of-use patents	Acne or bacterial disease treatment	Claims 28 and 32 have treatment language, but the patent remains primarily formulation-based
Container patents	Valve, actuator or canister systems	May create separate rights outside 7,141,237
Manufacturing patents	Filling, mixing or propellant incorporation	May create process barriers independent of the composition claims

A freedom-to-operate review for a new clindamycin foam should therefore examine the entire family and related assignee portfolio, not only 7,141,237. It should include continuation patents, divisionals, formulation patents, device patents and manufacturing claims in the United States and target markets.

What generic launch scenarios exist?

Scenario 1: Conventional post-expiry launch

A manufacturer launches after confirming that no later unexpired patent covers the formulation, container or manufacturing process. This is the lowest patent-risk scenario.

Scenario 2: Design-around foam launch

The manufacturer uses a different fatty alcohol, surfactant, propellant, container system or foam-breaking mechanism. This approach can reduce historical infringement risk but may create additional bioequivalence and product-performance work.

Scenario 3: Nonfoam clindamycin launch

The manufacturer develops a gel, solution, lotion or other topical dosage form. This avoids the central aerosol-foam limitations but competes against a different reference product and may require a separate regulatory strategy.

Scenario 4: Authorized or licensed launch

A generic or branded company enters through a license, acquisition or authorized-generic arrangement. Corporate ownership records alone do not establish that such a license exists.

What is the geographic coverage of the patent?

U.S. Patent 7,141,237 provides protection only in the United States. Foreign counterparts, if granted, require separate analysis by jurisdiction. Patent term, claim scope, validity, Orange Book relevance and litigation history vary across Canada, Europe, Japan, Australia and other markets.

A U.S. expiration does not establish freedom to operate in foreign markets. The international landscape should be reviewed through the patent family, national-phase records, legal-status databases and local patent registers.

Key Takeaways

U.S. Patent 7,141,237 covers a pressurized clindamycin phosphate foam composition.
The core combination is clindamycin phosphate, C1-C6 alcohol, C14-C22 fatty alcohol, water, surfactant, base and aerosol propellant.
The product must form a quick-breaking temperature-sensitive foam after discharge.
The patent does not cover clindamycin phosphate generally or every topical clindamycin dosage form.
Claims 2-4, 6, 29 and 30 contain inconsistent alcohol-water ratio language.
Claim 32 contains a potential inconsistency between the required surfactant in claim 1 and its 0% surfactant language.
The patent expired no later than 2023 and is not a current U.S. blocking right.
Remaining commercial barriers are primarily regulatory, manufacturing and formulation-performance barriers.
A current freedom-to-operate review must examine later patents covering the container, foam system, manufacturing method and any product-specific formulation.

FAQs

Does U.S. Patent 7,141,237 cover Evoclin itself?

It appears directed to the formulation technology associated with clindamycin phosphate aerosol foam products such as Evoclin, but product-specific claim coverage requires the complete quantitative formulation and patent-history record.

Can a company launch clindamycin phosphate foam after this patent expired?

Yes, expiration removes this patent as a current U.S. infringement barrier. The company must still address FDA approval requirements and any later unexpired patents.

Does the patent cover clindamycin phosphate gel?

No. The issued claims require a pressurized container and a quick-breaking foam after release. A conventional gel would not satisfy those limitations.

Are method-of-use claims 28 and 32 still enforceable?

No. Their patent term ended with the patent. Their treatment language does not extend the patent term or create current exclusivity.

Can a different propellant avoid the patent?

Potentially. A different propellant alone may not avoid claim 1 because the claim lists broad propellant categories and mixtures. The complete composition and foam-performance limitations must be evaluated together.

References

United States Patent and Trademark Office. (n.d.). Patent term adjustment and patent term calculation resources. https://www.uspto.gov/patents/laws/adjustment
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations, Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases
United States Patent and Trademark Office. (2006). U.S. Patent No. 7,141,237, Topical delivery compositions. https://patents.google.com/patent/US7141237B2
U.S. Food and Drug Administration. (2005). Evoclin clindamycin phosphate foam prescribing information. FDA Drugs@FDA database. https://www.accessdata.fda.gov/scripts/cder/daf/

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	042906	⤷ Start Trial
Argentina	082432	⤷ Start Trial
Australia	2004206769	⤷ Start Trial
Australia	2009235974	⤷ Start Trial
Brazil	PI0406905	⤷ Start Trial
Canada	2513773	⤷ Start Trial
Eurasian Patent Organization	009031	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Summary for Patent: 7,141,237