United States Patent 5,037,635: Claim Scope, Expiration, and Oral-Care Patent Landscape

U.S. Patent No. 5,037,635 covers oral compositions combining a substantially water-insoluble, noncationic halogenated diphenyl ether antibacterial agent, a synthetic anionic polycarboxylate, and a solubilizing system that prevents antibacterial-agent precipitation when the composition is diluted by saliva. The principal commercial target was triclosan-containing mouthrinse and dentifrice formulations using a vinyl methyl ether/maleic acid or anhydride copolymer, commonly known as Gantrez-type polymer.

The patent was granted on August 6, 1991. Applying the pre-1995 U.S. patent-term rule, its ordinary term expired on August 6, 2008, absent an unusual term adjustment or continuing enforceable rights. The claims are therefore no longer enforceable as patent rights in the United States.[1]

What invention does U.S. Patent 5,037,635 disclose?

The invention addresses a formulation problem: triclosan and related halogenated diphenyl ethers have limited water solubility and can precipitate when a concentrated oral formulation is diluted by saliva.

The patent requires a formulation that maintains the antibacterial agent in solution during use. Its architecture has four principal elements:

Claim element	Functional requirement
Oral vehicle	An orally acceptable vehicle
Water-humectant phase	Water and humectant together comprise at least about 10% by weight
Antibacterial agent	An effective antiplaque amount of a substantially water-insoluble, noncationic halogenated diphenyl ether
Polycarboxylate	About 0.0005% to 4% of a synthetic anionic polymeric polycarboxylate with molecular weight of about 1,000 to 1,000,000
Solubilizing system	Present in an amount sufficient to dissolve the antibacterial agent and prevent precipitation after saliva dilution

The claim is directed to formulation performance, not merely to the presence of triclosan. A product must satisfy the solubility and anti-precipitation limitation as well as the compositional limitations.

What compounds fall within the antibacterial-agent limitation?

The claim uses a structural and functional genus rather than naming a single active ingredient. The relevant compound must be:

A diphenyl ether;
Halogenated;
Substantially water-insoluble; and
Noncationic.

Triclosan, also known as 5-chloro-2-(2,4-dichlorophenoxy)phenol, is the principal commercial compound associated with this claim scope. Its three chlorine atoms and diphenyl ether structure fit the claimed class.

The language may also reach other halogenated diphenyl ethers if they meet the water-insolubility and noncationic requirements. The claim does not require the antibacterial agent to be triclosan, and a non-triclosan product could have fallen within the claim before expiration if it met all limitations.

The claim does not cover every halogenated oral antiseptic. A cationic antibacterial agent, a non-diphenyl-ether antibacterial, or a water-soluble antibacterial compound would not literally satisfy this limitation.

How does the solubilizing-agent limitation affect claim scope?

The solubilizing-agent requirement is central to claim 1. It requires more than the presence of ethanol, humectant, surfactant, or another solvent. The selected material or system must:

Solubilize the substantially water-insoluble antibacterial agent; and
Prevent precipitation when the composition is diluted with saliva during oral use.

This creates a functional limitation that would have required technical analysis in an infringement dispute. Relevant evidence could include:

Concentration of triclosan or another antibacterial agent;
Solubility measurements in the finished product;
Dilution testing using artificial or human saliva;
Visual, microscopic, chromatographic, or turbidity analysis;
Stability data over the commercial shelf life;
The identity and concentration of ethanol, propylene glycol, glycerin, polyethylene glycol, surfactants, or other solubilizers.

A formulation containing a solubilizer at a nominal concentration would not necessarily satisfy the claim unless the system performs the claimed anti-precipitation function. Conversely, a formulation could present infringement risk even if its labeling does not identify the solubilizer as a distinct formulation ingredient.

What does claim 1 require?

Claim 1 is the broadest independent claim. It requires the following combination:

Requirement	Scope assessment
Oral composition	Covers compositions intended for oral administration or use
Water-humectant phase	At least about 10% by weight of water and humectant
Antibacterial agent	Effective antiplaque amount of a substantially water-insoluble, noncationic halogenated diphenyl ether
Polycarboxylate	0.0005% to 4% by weight; molecular weight approximately 1,000 to 1,000,000
Solubilizer	Must dissolve the antibacterial agent and prevent precipitation on saliva dilution

The claim does not require:

A mouthrinse;
Ethanol;
A dentifrice abrasive;
Fluoride;
An anticalculus polyphosphate;
A particular flavor system;
A particular packaging format; or
A specific brand or trade name.

The claim could therefore reach both liquid and semisolid oral formulations, provided the water-humectant and solubility conditions are met.

What formulations are protected by claims 2 through 10?

Mouthrinse claims

Claim 2 narrows claim 1 to a mouthrinse containing approximately 70% to 99.9% by weight of a water-alcohol mixture. The water-to-alcohol weight ratio must be approximately 1:1 to 20:1.

Claim 3 further requires ethanol as the alcohol.

The claim 2 ratio excludes many low-alcohol or alcohol-free mouthrinses. A composition with no ethanol could still fall within claim 2 if another alcohol satisfied the claim, but claim 3 would not apply.

Gantrez-type polymer claim

Claim 4 is commercially important because it identifies a preferred polymer:

A water-soluble alkali-metal or ammonium salt;
Of a copolymer of vinyl methyl ether and maleic acid or maleic anhydride;
Present at approximately 0.1% to 2% by weight;
With a molecular weight of approximately 30,000 to 500,000.

The supplied text states “500,00,” which is evidently a typographical truncation. The technical range is ordinarily understood as approximately 30,000 to 500,000 molecular weight.

This limitation points to Gantrez-type copolymers, particularly salts of poly(methyl vinyl ether/maleic acid). The narrower claim would not cover every anionic polycarboxylate. A formulation using a different polymer, such as a carboxymethyl cellulose, polyacrylate, or unrelated copolymer, would require separate analysis under the broader claim 1.

Anticalculus formulations

Claim 5 adds an effective anticalculus amount of at least one linear molecularly dehydrated polyphosphate salt.

Claim 6 narrows the polyphosphate to approximately 0.1% to 7% by weight and identifies tetrasodium pyrophosphate. The claim language treats the polyphosphate as an essential anticalculus agent, which makes the limitation material rather than optional.

Claim 7 adds a fluoride source supplying approximately 25 to 2,000 parts per million fluoride ion. Claim 8 specifies sodium fluoride as the fluoride source.

Claim 9 adds the same fluoride-ion range directly to claim 1 without requiring the polyphosphate limitation of claim 5.

Toothpaste and gel claims

Claim 10 covers a toothpaste or gel dentifrice containing a dentally acceptable water-insoluble polishing agent.

Typical polishing agents potentially relevant to this limitation include hydrated silica, calcium carbonate, dicalcium phosphate, alumina, and related dentifrice abrasives. The claim does not specify the abrasive identity or concentration, but the material must be water-insoluble and dentally acceptable.

The claim is therefore directed to the combination of:

The halogenated diphenyl ether;
The anionic polycarboxylate;
The solubilizing system;
A water-insoluble polishing agent; and
A toothpaste or gel format.

How many patents cover the same formulation concept?

The relevant U.S. landscape is better understood as a layered portfolio than as a single blocking patent.

Technology layer	Typical protection sought	Relevance to U.S. 5,037,635
Antibacterial active	Triclosan and related halogenated diphenyl ethers	Core active-agent limitation
Polymer delivery system	Gantrez-type anionic polycarboxylates	Expressly narrowed in claim 4
Solubilization	Alcohol, humectant, surfactant, glycol, or mixed solvent systems	Functional limitation in claim 1
Mouthrinse	Water-alcohol compositions	Claims 2 and 3
Dentifrice	Abrasive toothpaste and gel systems	Claim 10
Anticalculus	Pyrophosphate and other linear polyphosphates	Claims 5 and 6
Anticaries	Sodium fluoride or another fluoride source	Claims 7 through 9
Product-specific patents	Commercial formulations, ratios, packaging, or manufacturing processes	Potentially separate from the expired patent

The patent is best viewed as an early formulation patent covering the compatibility of triclosan-type antibacterials with anionic polymer systems and saliva-dilution stability. Later patents could have addressed narrower commercial formulations, improved stability, reduced staining, flavor masking, lower alcohol levels, alternative fluoride systems, or manufacturing methods. Those later rights would need to be evaluated independently because expiration of U.S. 5,037,635 does not extinguish later patents.

When did U.S. Patent 5,037,635 lose exclusivity?

Event	Date or status
Patent grant	August 6, 1991
Ordinary pre-1995 U.S. term	17 years from grant
Expected expiration	August 6, 2008
Current enforceability	Expired
Current generic-entry relevance	No direct blocking effect from this patent

The patent was granted before the U.S. changed to the modern twenty-year term measured from the earliest effective nonprovisional filing date. For this grant, the relevant ordinary term is therefore tied to the grant date rather than a twenty-year period from the priority filing date.[1][2]

The expired patent cannot support a new infringement claim against a current oral-care product. It may still have commercial and technical importance as prior art and as evidence of formulation history.

What was the FDA regulatory status of the covered products?

The patent itself did not create FDA exclusivity. FDA approval and patent rights were separate.

Triclosan-containing oral-care products were regulated through product-specific FDA approval and OTC-drug frameworks. Colgate-Palmolive obtained FDA approval for Colgate Total in the 1990s, with triclosan used as the antibacterial ingredient and a copolymer used to support retention and delivery. The relevant regulatory issues included:

Antigingivitis or antiplaque activity;
Anticaries activity when fluoride was present;
Product-specific safety and effectiveness data;
Ingredient concentration;
Labeling and directions for use;
Compatibility of the antibacterial agent with the dentifrice base.

The 2016 FDA rule concerning consumer antiseptic washes did not directly determine the regulatory status of toothpaste or other oral-care products. The rule addressed consumer antiseptic wash products and did not operate as a blanket prohibition on all triclosan-containing products.[3]

What is the Orange Book status?

U.S. Patent 5,037,635 is not a current Orange Book exclusivity barrier. It expired in 2008 and cannot presently delay approval of a competing oral-care product.

Orange Book relevance would arise only if the patent had been submitted for listing in connection with an approved drug application and remained unexpired. An expired patent does not provide current patent protection even if historical listing information appears in regulatory records. OTC monograph products and cosmetics also differ from NDA products in how patent information is submitted and used.

Were Paragraph IV challenges relevant?

Paragraph IV litigation is generally associated with an Abbreviated New Drug Application that certifies that a listed patent is invalid, unenforceable, or will not be infringed.

For this patent:

A Paragraph IV certification could have been relevant during the patent’s unexpired term if the product was approved through an ANDA pathway and the patent was properly listed.
After August 6, 2008, the patent no longer created a live Paragraph IV litigation risk.
A modern generic applicant would not need to address this patent as an enforceable barrier.
The commercial products most closely associated with triclosan dentifrice were not necessarily approved through a conventional small-molecule ANDA pathway.

No reliable current basis exists to treat U.S. 5,037,635 as an active Paragraph IV litigation asset.

Which companies challenged or competed with the patent estate?

The principal competitive positions were held by:

Company	Relevant commercial position
Colgate-Palmolive	Triclosan-based antibacterial dentifrice and the commercial technology most closely associated with this formulation approach
Procter & Gamble	Competing oral-care portfolio using fluoride, stannous fluoride, antibacterial, anticalculus, and delivery-system technologies
GlaxoSmithKline	Sensodyne, Aquafresh, and other oral-care products using alternative active ingredients and formulation approaches
Church & Dwight	Arm & Hammer oral-care products, including bicarbonate-based and fluoride formulations
Private-label manufacturers	Products using generic fluoride, anticalculus, desensitizing, or cosmetic formulations

The most important competitive distinction was not simply whether a product contained an antibacterial agent. It was whether the product used the same combination of antibacterial active, anionic polymer, and saliva-dilution solubilization system.

How strong was the patent estate?

Strengths during the patent term

The patent had several features that could have made it commercially significant before expiration:

Claim 1 used a functional solubility limitation rather than naming only triclosan.
The claims covered both mouthrinses and dentifrices.
The polymer range was broad in claim 1.
Claim 4 directly addressed a commercially useful Gantrez-type polymer.
The dependent claims added fluoride and anticalculus products.
The claims were directed to a formulation problem that could be difficult to identify from product labeling alone.

Weaknesses and design-around opportunities

The patent also presented design-around paths:

Replace the halogenated diphenyl ether with another antibacterial class.
Use a cationic antibacterial agent.
Use an antibacterial compound outside the diphenyl-ether genus.
Use a different polymer or no polymer.
Change the solvent and humectant system so the saliva-dilution limitation is not met.
Use an alcohol-free system that does not satisfy the mouthrinse limitations.
Avoid the claimed polyphosphate or fluoride limitations.
Develop a formulation in which precipitation behavior differs from the claimed performance.

The functional language could also create proof issues. A patent owner would need to establish that the accused product both solubilizes the antibacterial agent and prevents precipitation after saliva dilution. The broader claim would not automatically cover a product merely because it contains triclosan and a water-soluble polymer.

What generic launch risks existed?

During the active term, risk depended on product format:

Product type	Principal claim risk
Ethanol mouthrinse with triclosan and Gantrez	High exposure to claims 1, 2, 3, and 4
Fluoride mouthrinse with pyrophosphate	Potential exposure to claims 5 through 9
Triclosan toothpaste with silica abrasive	Potential exposure to claims 1, 4, 9, and 10
Alcohol-free triclosan rinse	Potential claim 1 exposure, but reduced risk under claims 2 and 3
Triclosan-free antibacterial product	Outside the central active-agent limitation
Noncationic non-diphenyl-ether antibacterial product	Potentially outside claim 1
Alternative-polymer formulation	Reduced exposure to claim 4, but not necessarily claim 1

Today, the patent creates no launch-blocking risk because it is expired. Current risk must instead be assessed against later patents covering active ingredients, fluoride systems, delivery polymers, formulations, manufacturing processes, or product-specific regulatory combinations.

Does the patent create biosimilar risk?

No. U.S. Patent 5,037,635 concerns small-molecule oral-care compositions, not a biologic drug. Biosimilar provisions under the Public Health Service Act do not apply.

The relevant competitive pathways are:

Generic or alternative NDA products;
OTC monograph products;
New drug applications for products with non-monograph claims;
Consumer oral-care products regulated as cosmetics or drugs depending on labeling and active ingredients.

What manufacturing and intellectual-property barriers remain?

The expired patent does not prevent manufacture of the claimed formulations. Commercial barriers may remain in other areas:

Control of triclosan particle size and dissolution;
Prevention of active precipitation during storage;
Compatibility with fluoride and pyrophosphate;
Flavor and odor masking;
Control of polymer viscosity;
Preservation and microbial stability;
Abrasive compatibility in dentifrices;
Regulatory substantiation for antiplaque or antigingivitis claims;
Later patents on replacement antibacterial agents or stannous-fluoride systems.

A freedom-to-operate review should therefore separate three questions:

Whether the product practices U.S. 5,037,635;
Whether the patent is still enforceable; and
Whether later patents cover the same commercial product.

For the second question, the answer is no. The patent expired in 2008.

Key Takeaways

U.S. Patent 5,037,635 covers oral compositions using a substantially water-insoluble, noncationic halogenated diphenyl ether, most notably triclosan.
The core formulation requirement is a solubilizing system that prevents precipitation after saliva dilution.
Claim 1 is broad and applies to oral compositions generally, while claims 2 through 10 narrow the invention to mouthrinses, Gantrez-type polymers, polyphosphates, fluoride, and toothpaste or gel formats.
Claim 4 is particularly relevant to vinyl methyl ether/maleic acid or anhydride copolymers.
The patent’s ordinary U.S. term expired on August 6, 2008.
It is no longer an enforceable patent or a current generic-entry barrier.
It does not create biosimilar risk.
FDA approval and Orange Book listing, if historically relevant, did not extend the patent term.
Current freedom-to-operate risk depends on later patents, not on U.S. 5,037,635.

FAQs

Is triclosan specifically named in U.S. Patent 5,037,635?

The supplied claim language does not name triclosan. It claims a broader class of substantially water-insoluble, noncationic halogenated diphenyl ether antibacterial agents. Triclosan is the principal compound associated with that class.

Does the patent cover alcohol-free mouthwash?

An alcohol-free product would not satisfy the ethanol limitation in claim 3 and would not satisfy claim 2’s water-alcohol requirement. It could still be evaluated under claim 1 if it contains the required antibacterial agent, polycarboxylate, water-humectant phase, and solubilizing system.

Does claim 4 cover every Gantrez polymer?

No. Claim 4 requires a water-soluble alkali-metal or ammonium salt of a vinyl methyl ether/maleic acid or maleic anhydride copolymer within the stated concentration and molecular-weight ranges. Other Gantrez grades or polymers may require separate analysis.

Could a toothpaste infringe without fluoride?

Yes. Fluoride is not required by claim 1 or claim 10. Claims 7 through 9 add fluoride limitations, but a nonfluoride toothpaste could still be evaluated against the broader composition claims.

Can a company rely on the patent’s expiration for a current product launch?

A company can rely on the expiration of U.S. 5,037,635 to remove that patent as a current U.S. infringement barrier. It must still evaluate later patents, regulatory requirements, trademarks, trade secrets, and rights in other countries.

References

United States Patent and Trademark Office. (1991). U.S. Patent No. 5,037,635, Oral compositions containing antibacterial agents.
United States Code, 35 U.S.C. §§ 154, 156.
U.S. Food and Drug Administration. (2016). Safety and effectiveness of consumer antiseptic washes; topical antimicrobial drug products for over-the-counter human use. Federal Register, 81 Fed. Reg. 61106.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	243371	⤷ Start Trial
Argentina	244259	⤷ Start Trial
Austria	119764	⤷ Start Trial
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Details for Patent: 5,037,635

Summary for Patent: 5,037,635