United States Patent 4,298,604: Scope, Claims, Expiration, and Betamethasone-Clotrimazole Patent Landscape

United States Patent 4,298,604 covers pharmaceutical compositions combining clotrimazole and betamethasone dipropionate in defined concentration ranges and ratios. Its commercial center is the topical combination historically marketed as Lotrisone, generally containing 1% clotrimazole and 0.05% betamethasone dipropionate.

The patent issued on November 3, 1981. Under the pre-Uruguay Round patent-term rule, its ordinary 17-year term from grant would have ended on November 3, 1998. The patent therefore no longer creates an enforceable U.S. patent barrier to generic manufacture, sale, or FDA approval. Its claims remain relevant for historical scope, infringement analysis concerning past conduct, and interpretation of the original product concept, but not for current generic-entry exclusivity.

What does U.S. Patent 4,298,604 cover?

The patent covers a pharmaceutical composition containing two active ingredients:

Component	Claim 1 concentration	Commercially relevant concentration
Betamethasone dipropionate	About 0.001% to about 0.33% by weight	0.05%
Clotrimazole	About 0.01% to about 10% by weight	1%
Clotrimazole-to-betamethasone ratio	About 10:1 to about 30:1	20:1

The claim requires both active ingredients to be present in a pharmaceutically acceptable carrier. The carrier can be a cream, ointment, lotion, or another pharmaceutical vehicle, subject to the limitations imposed by the dependent claims.

The claim is composition-based. It does not require:

A specific dermatological indication;
A particular excipient;
A specific manufacturing process;
A named brand;
A particular package or applicator;
A particular particle size;
A specific dosing schedule;
A specific application site; or
A particular clinical outcome.

The use of the word “comprising” makes claim 1 open-ended. A composition containing the claimed concentrations and ratio can fall within the claim even if it also contains additional active or inactive ingredients, unless another legal limitation excludes the formulation.

How should the six claims be interpreted?

Claim 1: Broad combination-composition claim

Claim 1 is the principal scope-defining claim. It requires:

Betamethasone dipropionate at approximately 0.001% to 0.33% by weight;
Clotrimazole at approximately 0.01% to 10% by weight;
A clotrimazole-to-betamethasone dipropionate ratio of approximately 10:1 to 30:1; and
A pharmaceutically acceptable carrier.

All four elements are required.

The concentration ranges and ratio operate together. A formulation must satisfy the individual concentration limitations and the ratio limitation. A product with both ingredients inside the concentration ranges could still fall outside the claim if its ratio is below 10:1 or above 30:1.

For example:

Formulation	Clotrimazole:betamethasone ratio	Claim 1 result
1% / 0.05%	20:1	Within the stated range
1% / 0.06%	16.7:1	Within the stated range
2% / 0.05%	40:1	Outside the stated ratio
0.5% / 0.05%	10:1	At the lower ratio boundary
1.5% / 0.05%	30:1	At the upper ratio boundary

The word “about” introduces a claim-construction issue. Courts generally interpret “about” in light of the specification, prosecution history, technical measurement practices, and whether the accused formulation is materially different. The term does not eliminate the numerical limitations.

Claim 2: Narrower concentration ranges

Claim 2 depends on claim 1 and narrows the concentrations to:

Betamethasone dipropionate: approximately 0.01% to 0.1%;
Clotrimazole: approximately 0.1% to 2%.

The ratio limitation from claim 1 remains applicable. Claim 2 therefore does not cover every combination within its two concentration ranges. It covers only those combinations that also maintain the 10:1 to 30:1 clotrimazole-to-betamethasone ratio.

For example, 0.1% clotrimazole with 0.1% betamethasone has a 1:1 ratio and would not satisfy claim 1, even though both concentrations fall within the numerical ranges of claim 2.

Claim 3: Specific concentration embodiment

Claim 3 narrows the formulation to approximately:

0.06% betamethasone dipropionate; and
1% clotrimazole.

The resulting ratio is approximately 16.7:1, within claim 1’s ratio range.

The text supplied refers to “betamethasone” in claim 3, while claim 1 specifies betamethasone dipropionate. Because claim 3 depends on claim 1, the dependent claim should ordinarily be read in the context of the parent limitation. The issued patent and prosecution record control the legally operative wording.

Claim 3 is narrower than the commercial 1%/0.05% formulation often associated with clotrimazole-betamethasone products. A 1%/0.05% formulation is within claim 1 and claim 2, but it is not literally the 1%/0.06% concentration stated in claim 3.

Claims 4, 5, and 6: Dosage-form limitations

Claims 4 through 6 limit the composition to a specific topical dosage form:

Claim 4: cream;
Claim 5: ointment;
Claim 6: lotion.

These claims do not create separate active-ingredient combinations. Each incorporates claim 1 and adds a dosage-form limitation.

A cream containing 1% clotrimazole and 0.05% betamethasone dipropionate would be evaluated under claim 1 and claim 4. An ointment with the same concentrations would be evaluated under claim 1 and claim 5. A lotion would implicate claim 1 and claim 6.

The patent does not, based on the supplied claims, require a particular rheology, emulsion type, oil phase, aqueous phase, preservative system, penetration enhancer, or packaging configuration.

What formulations are protected by Patent 4,298,604?

The most commercially significant formulation is a topical product containing:

1% clotrimazole; and
0.05% betamethasone dipropionate.

That formulation has a 20:1 clotrimazole-to-betamethasone ratio. It falls within claim 1 and the concentration ranges of claim 2. It would also fall within claims 4, 5, or 6 depending on whether the product is formulated as a cream, ointment, or lotion.

The patent’s numerical scope can be represented as follows:

Dosage form	1% clotrimazole / 0.05% betamethasone dipropionate
Cream	Within claims 1, 2, and 4
Ointment	Within claims 1, 2, and 5
Lotion	Within claims 1, 2, and 6

The claims do not expressly protect a particular treatment method. They protect the composition itself. A method-of-use patent would require separate claims directed to administering the formulation for a specified disease, patient population, dosing schedule, or treatment outcome. No such method limitation appears in the six claims provided.

When did U.S. Patent 4,298,604 lose exclusivity?

The patent issued November 3, 1981, as U.S. Patent 4,298,604. Its ordinary pre-1995 term was 17 years from issuance, producing an expiration date of November 3, 1998, absent an unusual term adjustment, disclaimer, or extension.

The patent predates the modern 20-year term measured from the earliest effective nonprovisional filing date. It also predates the principal Hatch-Waxman framework for Orange Book patent certifications and modern patent-term-extension practice.

Because the patent expired in 1998:

It cannot support a current injunction against a generic product;
It cannot support a current Paragraph IV exclusivity period;
It cannot block an ANDA approval;
It cannot create a current 30-month stay based on its listing; and
It does not provide current market exclusivity for the combination.

Patent expiration does not erase the historical patent record. It ends the right to exclude others from practicing the claimed invention.

What is the Orange Book status of the patent?

The Orange Book lists patents associated with approved drug products when the patents meet FDA listing requirements. A patent that expired in 1998 is not a current barrier to approval or commercial entry.

For clotrimazole and betamethasone dipropionate products, the relevant regulatory issue is the approved product’s FDA status and any currently listed patents, not the continued existence of U.S. Patent 4,298,604 in patent databases. An expired patent may appear in historical regulatory or patent records, but it does not carry present Orange Book exclusivity.

A generic applicant seeking approval of a formulation corresponding to the historical combination would generally address any currently listed patents for the reference product. Patent 4,298,604 itself would not create a present Paragraph IV risk because its term has ended.

Are there Paragraph IV challenges to Patent 4,298,604?

A Paragraph IV certification alleges that a listed patent is invalid, unenforceable, or will not be infringed by the proposed generic product. Such a certification has commercial significance only while the patent remains listed and unexpired.

Patent 4,298,604 is expired. A current applicant would not need to challenge it as an enforceable patent. The historical development of generic clotrimazole-betamethasone products may have involved patent certifications directed to other patents, regulatory exclusivity, or product-specific requirements, but the supplied claim set does not establish any particular Paragraph IV filing or litigation result.

The expired status eliminates the central economic effect of a Paragraph IV challenge: the possibility of a 30-month approval stay and a 180-day generic exclusivity period tied to the challenged patent.

Which companies challenged or commercialized products covered by the patent?

The claims identify no licensee, generic applicant, or litigation defendant. The patent was associated with the originator combination of clotrimazole and betamethasone dipropionate, while subsequent generic products have been approved by multiple manufacturers under FDA abbreviated-approval pathways.

A patent number alone does not establish:

A license agreement;
A settlement agreement;
A covenant not to sue;
A successful Paragraph IV challenge;
A particular ANDA sponsor; or
A finding of infringement.

Those conclusions require separate FDA, USPTO, court, and transaction records. The patent’s expiration means that any current competitive advantage must come from manufacturing scale, FDA approval status, formulation quality, distribution, branding, or other intellectual-property rights rather than this patent.

How strong is the patent estate for clotrimazole-betamethasone products?

The patent estate represented by Patent 4,298,604 is legally expired and has no current exclusionary strength. Its historical claim breadth was meaningful because claim 1 covered a wide concentration window and several topical carriers.

Its principal strengths were:

Coverage of the active-ingredient combination;
A ratio range broad enough to include common 1%/0.05% products;
Open-ended “comprising” language;
Coverage independent of a specific therapeutic indication; and
Dependent claims covering cream, ointment, and lotion presentations.

Its principal limitations were:

Dependence on numerical concentration and ratio boundaries;
No express coverage of manufacturing processes;
No express coverage of specific excipients or delivery technology;
No separate method-of-use claim in the supplied claims; and
A finite patent term that ended in 1998.

For current products, the more relevant IP risks would arise from later formulation, manufacturing, packaging, device, or method-of-use patents. The six claims supplied do not show protection for those categories.

What manufacturing and IP barriers remain after expiration?

Expiration removes the active-ingredient composition barrier but does not eliminate commercial or regulatory requirements. A competing manufacturer still must demonstrate that its product meets FDA requirements for quality, safety, efficacy, manufacturing controls, stability, labeling, and bioequivalence or other applicable topical-product standards.

Potential non-patent barriers include:

Scale-up of a uniform semisolid formulation;
Control of active-ingredient distribution;
Stability of the corticosteroid and antifungal components;
Microbial and preservative control;
Container-closure compatibility;
FDA product-quality requirements;
Manufacturing-site compliance; and
Distribution and reimbursement access.

These are operational and regulatory barriers, not continuing rights under Patent 4,298,604.

What is the generic launch risk?

The patent-related launch risk from Patent 4,298,604 is effectively zero because the patent expired decades ago. A generic entrant copying the claimed concentration range would not face an injunction based on this patent.

Current launch risks would instead depend on:

Risk category	Relevance of Patent 4,298,604
Patent infringement	No current risk from this expired patent
Paragraph IV litigation	No current risk from this expired patent
FDA approval	Independent of the expired patent
Formulation quality	Commercially important
Manufacturing compliance	Commercially important
Current later-filed patents	Requires separate review
Market competition	Potentially significant
Brand recognition	Relevant to pricing and prescribing

The combination product is also exposed to substitution pressure because the active ingredients are established, the formulation is relatively conventional, and the core composition patent is long expired.

What is the geographic coverage of Patent 4,298,604?

U.S. Patent 4,298,604 provides rights only in the United States. It does not establish protection in Canada, Europe, Japan, or other jurisdictions.

International protection would depend on separately filed national or regional patents, their claim scope, prosecution history, and expiration dates. A U.S. patent number cannot be used to infer foreign patent coverage.

Key Takeaways

Patent 4,298,604 covers compositions combining clotrimazole and betamethasone dipropionate in specified concentration ranges and a 10:1 to 30:1 ratio.
The common 1% clotrimazole/0.05% betamethasone dipropionate formulation falls within the principal composition claim.
Cream, ointment, and lotion forms are covered by dependent claims 4, 5, and 6.
The patent issued November 3, 1981, and its ordinary patent term ended November 3, 1998.
The patent creates no current U.S. generic-entry or Paragraph IV barrier.
The supplied claims contain no express manufacturing-process or method-of-use protection.
Any current risk must come from later patents, FDA requirements, manufacturing execution, or commercial competition.

FAQs

Does a 1% clotrimazole and 0.05% betamethasone dipropionate cream fall within the patent claims?

Yes. Its ratio is 20:1, which falls within claim 1’s 10:1 to 30:1 range. Its concentrations also fall within claim 2, and its cream dosage form falls within claim 4.

Does the patent cover a product containing 1% clotrimazole and 0.1% betamethasone dipropionate?

Yes, assuming the ingredients are betamethasone dipropionate and the ratio is calculated as 10:1. The formulation would fall at the lower ratio boundary of claim 1 and within claim 2’s concentration ranges.

Can an expired patent still be listed in the FDA Orange Book?

Historical patent records may remain accessible, but an expired patent does not provide current patent-based approval protection or an enforceable generic-entry block.

Does Patent 4,298,604 protect clotrimazole or betamethasone dipropionate individually?

No. The supplied claims require the combination of both active ingredients. They do not claim either ingredient alone.

Would changing the cream to an ointment avoid the patent?

No, during the patent term. The dependent claims expressly cover cream, ointment, and lotion forms, and claim 1 independently covers the composition in a pharmaceutically acceptable carrier. Today, the patent’s expiration makes the issue immaterial for current U.S. entry.

References

United States Patent and Trademark Office. (1981). U.S. Patent No. 4,298,604: Pharmaceutical composition containing clotrimazole and betamethasone dipropionate.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations. Orange Book.
U.S. Food and Drug Administration. (n.d.). Drugs@FDA: FDA-approved drug products.
United States Code, 35 U.S.C. § 154. Patent term.
United States Code, 21 U.S.C. § 355. New drug applications and abbreviated applications.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	7457	⤷ Start Trial
Australia	545282	⤷ Start Trial
Australia	7605081	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 4,298,604

Summary for Patent: 4,298,604