US Patent 4,894,220: Scope, Claim Construction, Expiration, and Oral-Care Patent Landscape

US Patent 4,894,220 protects oral compositions combining a substantially water-insoluble noncationic antibacterial agent, principally triclosan, with a synthetic anionic polymeric polycarboxylate and a humectant system capable of dissolving the antibacterial agent. The strongest claim concentration is in toothpaste, gel dentifrice, and mouthrinse formulations containing triclosan, propylene glycol, and a vinyl methyl ether-maleic acid or maleic anhydride copolymer.

The patent is expired and does not present a current US infringement barrier. Its technical disclosure remains relevant for freedom-to-operate analysis because later oral-care patents and commercial products may have adopted overlapping formulation concepts, but any live rights must be assessed in later patents rather than in US 4,894,220 itself.

What does US Patent 4,894,220 protect?

The patent claims a formulation architecture rather than a particular commercial product. Independent claim 1 requires all of the following:

An orally acceptable vehicle.
A water-humectant phase representing at least about 10% by weight of the composition.
A substantially water-insoluble, noncationic antibacterial agent.
An effective antiplaque amount of that antibacterial agent.
An anionic linear polymeric polycarboxylate at approximately 0.0005% to 4% by weight.
A humectant containing a specified solubilizing agent mixed with glycerine or sorbitol.
Sufficient solubilizing humectant to dissolve the antibacterial agent.

The principal technical combination is:

triclosan or another halogenated diphenyl ether + propylene glycol or another specified solubilizer + anionic polycarboxylate.

The claim is directed to compositions, not to a manufacturing process, dosing regimen, patient population, or therapeutic method.

What antibacterial agents fall within the claims?

The broad antibacterial class is “halogenated diphenyl ethers.” Claim 5 narrows the compound to 2,4,4'-trichloro-2-hydroxy-diphenyl ether, commonly known as triclosan.

Potentially relevant compounds include:

Triclosan.
Other halogenated diphenyl ethers meeting the claim language.
Compounds that are substantially water insoluble and noncationic.

A product containing an antibacterial agent outside the halogenated diphenyl ether class would not literally satisfy the antibacterial-agent limitation. Cationic agents, such as chlorhexidine salts or quaternary ammonium compounds, are outside the express group in claim 1, subject to any separate infringement theory.

What polymeric polycarboxylates are covered?

Claim 1 covers a broad molecular-weight range of approximately 1,000 to 1,000,000. Claim 6 narrows the polymer to a water-soluble alkali-metal or ammonium salt of a copolymer of vinyl methyl ether and maleic acid or maleic anhydride, with a molecular weight of approximately 30,000 to 500,000.

This language is associated with Gantrez-type polymers, particularly salts of methyl vinyl ether/maleic anhydride copolymers. Claim 6 requires a concentration of about 0.1% to 2%.

A formulation using a different anionic polycarboxylate may fall within claim 1 if it satisfies the broader structural and molecular-weight limitations. A formulation using a polymer outside the claimed molecular-weight range or lacking the required anionic linear polycarboxylate may avoid literal infringement.

How do the claims narrow from claim 1 to claim 18?

Claims	Main limitation	Commercial formulation relevance
1	Broad oral composition with antibacterial agent, humectant-solubilizer system, and anionic polycarboxylate	Core combination
2	0.5%-50% propylene glycol	Broadens practical formulation coverage for propylene-glycol systems
3	0.01%-5% halogenated diphenyl ether	Covers common antibacterial concentrations
4	0.1%-0.5% antibacterial agent	Targets conventional triclosan levels
5	Antibacterial agent is triclosan	Narrow compound claim
6	0.1%-2% Gantrez-type polycarboxylate salt	Important commercial subcombination
7	Adds linear molecularly dehydrated polyphosphate anticalculus agent	Anticalculus toothpaste
8	0.1%-7% polyphosphate, specifically tetrasodium pyrophosphate	Tartar-control formulation
9-11	Fluoride ion source supplying 25-2,000 ppm fluoride	Fluoride toothpaste and rinse
12	Water-insoluble polishing agent; toothpaste or dentifrice	Dentifrice format
13	Propylene glycol, gelling agent, polishing agent, toothpaste or gel	Commercial gel and paste
14	Specific antibacterial, polycarboxylate, and propylene glycol levels	Narrow formulation claim; text contains an apparent transcription error
15	Silica polishing material	Silica-based toothpaste
16	70%-99.9% water/alcohol mixture; mouthrinse	Rinse format
17	Alcohol is ethanol	Conventional ethanol mouthrinse
18	5%-20% propylene glycol	Propylene-glycol mouthrinse

Claim 1 is the principal scope anchor. Claims 2 through 18 are dependent claims and require every limitation of claim 1 plus their added restrictions.

What are the most important claim limitations for freedom-to-operate?

The most important limitations are cumulative. A competing product generally must be evaluated against the entire combination, not against isolated ingredients.

1. Substantially water-insoluble noncationic antibacterial agent

Triclosan is the clearest target. A product using cetylpyridinium chloride, chlorhexidine, essential oils, stannous compounds, or another non-halogenated antibacterial would not satisfy this limitation literally.

2. Anionic linear polymeric polycarboxylate

This is a central structural limitation. A product containing no polymeric polycarboxylate is outside the literal scope of claim 1. A formulation containing a thickener, cellulose derivative, carbomer, or ordinary polyacrylate is not automatically equivalent to the claimed polymer.

3. Solubilizing humectant

The claim requires a solubilizing agent selected from a closed-looking list:

Propylene glycol.
Dipropylene glycol.
Methyl cellosolve.
Ethyl cellosolve.
Olive oil.
Castor oil.
Amyl acetate.
Ethyl acetate.
Glyceryl tristearate.
Benzyl benzoate.

The selected agent must be mixed with glycerine or sorbitol, and the amount must be sufficient to dissolve the antibacterial agent. This functional requirement creates a formulation-specific issue: mere presence of propylene glycol may not be enough if the product does not use it in an amount that dissolves the antibacterial agent.

4. Water-humectant phase

The composition must contain at least about 10% by weight of water and humectant. This limitation is particularly relevant to high-solids dentifrices, anhydrous pastes, and concentrated oral-care products.

What formulations are protected by US 4,894,220?

Triclosan toothpaste

The clearest covered formulation would contain:

Triclosan at approximately 0.1%-0.5%.
Propylene glycol.
Glycerine or sorbitol.
A Gantrez-type polycarboxylate salt.
Water.
A polishing agent, particularly silica.
Optional fluoride.
Optional tetrasodium pyrophosphate.

Claims 3, 4, 5, 6, 12, 13, and 15 collectively describe this formulation profile.

Triclosan anticalculus toothpaste

Claims 7 and 8 add a polyphosphate, particularly tetrasodium pyrophosphate, as an anticalculus agent. A product containing triclosan, the claimed polymer, and tetrasodium pyrophosphate would implicate the narrow anticalculus subcombination if the other claim 1 requirements were met.

Fluoride toothpaste

Claims 9 through 11 cover fluoride-containing compositions supplying approximately 25 to 2,000 ppm fluoride ion. Claim 10 identifies sodium fluoride, but the broader claims are not limited to sodium fluoride.

A typical covered profile would include:

Triclosan.
Sodium fluoride.
Silica.
Glycerine or sorbitol.
Propylene glycol.
Gantrez-type copolymer salt.
Water.

Mouthrinse

Claims 16 through 18 address a different dosage form. The rinse must contain approximately 70%-99.9% of a water-alcohol mixture with a water-to-alcohol ratio of approximately 1:1 to 20:1. Claim 17 specifies ethanol, and claim 18 adds 5%-20% propylene glycol.

The mouthrinse claims therefore require more than triclosan and polymer. They require the specified high-percentage water/alcohol vehicle and, for claim 18, the propylene glycol range.

What is the patent expiration date of US 4,894,220?

US Patent 4,894,220 is expired. The patent issued in 1990, and its enforceable term ended no later than the ordinary 20-year term measured from the applicable US nonprovisional filing date under the modern patent-term regime. Any term adjustment or terminal disclaimer would need to be confirmed from the USPTO patent file, but it would not change the present conclusion that the patent is no longer enforceable.

Item	Assessment
Patent	US 4,894,220
Technology	Antibacterial oral compositions
Primary active	Triclosan and related halogenated diphenyl ethers
Key excipients	Propylene glycol, glycerine, sorbitol, polycarboxylate
Key polymer	Vinyl methyl ether/maleic acid or maleic anhydride copolymer salts
Formats	Toothpaste, gel dentifrice, mouthrinse
Current US enforceability	Expired
Current Paragraph IV risk from this patent	None
Current Orange Book listing value	None for an expired oral-care formulation patent

The expiration conclusion follows from the patent’s age and the statutory patent-term framework in 35 U.S.C. § 154. The patent cannot block a current generic or branded product solely because that product practices the disclosed combination.

What is the Orange Book status of US 4,894,220?

US 4,894,220 is not a meaningful current Orange Book barrier.

The FDA Orange Book primarily lists patents submitted for approved drug products under the Hatch-Waxman framework. Conventional toothpaste and mouthrinse products regulated as cosmetics, anticaries drugs, or OTC monograph products do not create the same Orange Book patent ecosystem as prescription drugs.

The patent’s subject matter is an oral-care composition. It is not a patent on an FDA-approved prescription drug product. Its relevance is therefore principally historical and technical, not as a current Orange Book-listed patent.

When does triclosan oral-care exclusivity lose protection?

The patent-based exclusivity for the claimed composition has already ended. Separate regulatory and patent issues remain distinct:

US 4,894,220 no longer provides enforceable composition claims.
Triclosan itself is not protected by this patent as a chemical compound.
Later patents may have covered different triclosan combinations, delivery systems, concentrations, or uses.
FDA status for triclosan varies by product category and intended use.
A formulation may be commercially unavailable or restricted for regulatory reasons even when the patent barrier has expired.

The FDA’s 2016 final rule excluded triclosan and certain other active ingredients from consumer antiseptic wash products because manufacturers had not demonstrated the required long-term safety and efficacy profile for that use. That action did not itself invalidate oral-care patents or determine the patent status of toothpaste formulations. FDA treatment must be analyzed by product category. (U.S. Food and Drug Administration, 2016)

What later patents and companies are relevant to this landscape?

The principal commercial and technical landscape involved Colgate-Palmolive and other oral-care manufacturers developing triclosan dentifrices, polymer-assisted substantivity systems, fluoride combinations, anticalculus compositions, and mouthrinses.

Colgate-Palmolive

Colgate-Palmolive is the most directly associated commercial entity in the historical triclosan-polycarboxylate oral-care field. The patent’s claim structure is consistent with an effort to improve the retention, dispersion, and antiplaque effectiveness of a poorly water-soluble antibacterial agent in a dentifrice or rinse.

Relevant follow-on searching should focus on later Colgate families concerning:

Triclosan substantivity.
Gantrez and related copolymers.
Fluoride compatibility.
Silica dentifrices.
Anticalculus systems.
Mouthrinse vehicles.
Dual-active oral compositions.

Procter & Gamble

Procter & Gamble’s relevant oral-care activity has generally centered on fluoride dentifrices, stannous fluoride, anticalculus systems, abrasive technology, and delivery systems. The company’s products may overlap with individual elements of the patent, but ingredient overlap alone does not establish claim coverage.

GlaxoSmithKline and Haleon

Historical oral-care portfolios associated with GlaxoSmithKline include fluoride, sensitivity, antiplaque, and mouthrinse technologies. Later Haleon portfolios should be searched for active patents covering specific formulations and delivery systems rather than relying on the expired 1990 patent.

Unilever

Unilever has held oral-care patents involving toothpaste composition, abrasive systems, antimicrobial agents, and delivery technologies. A current competitive assessment must distinguish expired triclosan claims from live patents on current actives, such as zinc salts, stannous compounds, arginine, or specialized delivery systems.

Which companies are challenging US 4,894,220?

No current Paragraph IV challenge is relevant because the patent is expired. Paragraph IV litigation is principally associated with listed patents for approved drug products and abbreviated new drug applications. A decades-old oral-care composition patent would not ordinarily generate a present-day Paragraph IV dispute.

Historical litigation, reexamination, terminal-disclaimer, assignment, and maintenance-fee records should be checked in the USPTO and court databases before relying on any assertion about prior enforcement. The claims provided do not establish whether the patent was litigated, licensed, reexamined, or subject to a terminal disclaimer.

How strong is the patent estate for US 4,894,220?

Historical strength

The patent had meaningful historical scope because claim 1 combined four commercially important elements:

A known but poorly water-soluble antibacterial agent.
A humectant-solubilizer system.
A polymeric polycarboxylate.
An oral-care vehicle.

The dependent claims then mapped the combination to commercially common dosage forms and ingredients.

Current strength

Its current legal strength is zero as an enforceable US patent because the patent has expired. Its residual value is limited to:

Prior-art evidence.
Historical formulation disclosure.
Technical guidance for claim-charting later patents.
Identification of ingredient combinations that may recur in later patent families.

Vulnerabilities in claim scope

The claims contain several potential design-around points:

Use a non-halogenated antibacterial.
Omit the anionic linear polycarboxylate.
Use a polymer outside the stated structural or molecular-weight scope.
Use a solvent not listed in claim 1.
Use an antibacterial system that does not require the claimed solubilizing humectant.
Reduce the water-humectant phase below the claimed threshold.
Use a different dosage form or vehicle that does not meet the mouthrinse limitations.
Use a different anticalculus agent where claims 7 and 8 are being considered.

Because the patent is expired, these design-arounds have no current infringement purpose for this patent. They remain relevant when assessing whether later patents adopted similar claim strategies.

What manufacturing and formulation barriers did the patent address?

Triclosan has limited water solubility. The patent addresses the practical problem of incorporating it into water-rich oral-care compositions while maintaining antiplaque performance.

The claimed formulation strategy uses:

Propylene glycol or another listed solubilizer.
Glycerine or sorbitol as the principal humectant.
A polycarboxylate to improve antibacterial delivery or retention.
Optional silica, fluoride, and polyphosphate components.

The manufacturing implications include control of:

Triclosan dissolution before incorporation.
Order of addition.
Polymer hydration.
Compatibility with fluoride and polyphosphate salts.
Viscosity and gel structure.
Stability during storage.
Uniformity of active concentration.

These process parameters may have been commercially important even though the patent does not claim a manufacturing process directly.

How does US 4,894,220 compare with modern oral-care patent strategies?

Patent strategy	US 4,894,220	Modern oral-care strategy
Antibacterial	Halogenated diphenyl ether, mainly triclosan	Stannous fluoride, zinc, arginine, essential oils, CPC, novel antimicrobials
Delivery	Solubilizing humectant and polycarboxylate	Encapsulation, nanoparticles, controlled release, polymer substantivity
Dosage forms	Toothpaste, gel, mouthrinse	Toothpaste, serum, strips, tablets, foams, professional varnishes
Anticalculus	Linear polyphosphate salts	Polyphosphates, zinc systems, enzyme and biofilm approaches
Fluoride	25-2,000 ppm fluoride ion	Sodium fluoride, stannous fluoride, sodium monofluorophosphate
Claim focus	Composition and ingredient ranges	Composition, manufacturing, delivery, microbiome, treatment method, packaging
Current status	Expired	Later families may remain active

The major shift is from claiming a specific antimicrobial-solubilizer-polymer combination to claiming delivery platforms, active compatibility, biofilm effects, sensory properties, and treatment methods.

What litigation and settlement issues affect the patent?

The supplied claim text does not establish a litigation history, settlement agreement, license, covenant not to sue, or ownership transfer. Because the patent is expired, any historical settlement would have no present ability to extend the statutory patent term.

A current diligence conclusion should therefore treat:

Patent expiration as dispositive for present US enforcement.
Any historical litigation as useful only for claim-construction or validity context.
Any license as commercially relevant only if it included know-how, trademarks, regulatory data, or other non-patent rights.
Later continuation or divisional patents as the only possible source of continuing patent rights from the same disclosure.

What is the commercial and revenue exposure?

US 4,894,220 presents no current direct revenue exposure from patent royalties or injunction risk. Historical revenue exposure may have been significant because the claims targeted mass-market dentifrice and mouthrinse products containing triclosan and conventional fluoride or anticalculus ingredients.

The commercially relevant product categories were:

Antiplaque toothpaste.
Gel dentifrice.
Fluoride toothpaste.
Tartar-control toothpaste.
Ethanol mouthrinse.
Propylene-glycol mouthrinse.

Current revenue analysis should focus on later live patents, regulatory permissions, brand rights, and formulation know-how. The expired patent itself cannot support a current royalty demand in the United States.

Key Takeaways

US Patent 4,894,220 claims oral compositions combining a water-insoluble noncationic antibacterial, especially triclosan, with an anionic polymeric polycarboxylate and a solubilizing humectant.
The principal commercial targets are toothpaste, gel dentifrice, fluoride toothpaste, anticalculus toothpaste, and mouthrinse.
Claim 6 is particularly important for Gantrez-type vinyl methyl ether/maleic acid or maleic anhydride copolymers.
Claims 12 through 15 focus on toothpaste and silica dentifrice formulations.
Claims 16 through 18 cover high-water/high-alcohol mouthrinses, including ethanol and propylene glycol systems.
The patent is expired and creates no current US infringement, Paragraph IV, or Orange Book barrier.
Any present freedom-to-operate risk must come from later patents, not US 4,894,220.
The claim text contains apparent transcription defects, including “systematic” rather than “synthetic” and an unclear concentration in claim 14. The issued patent should control for formal claim construction.
The historical technical contribution was the use of a solubilizing humectant and polycarboxylate to formulate and deliver triclosan in water-rich oral-care products.

FAQs

Does US 4,894,220 cover triclosan by itself?

No. The claims require triclosan or another qualifying antibacterial agent in combination with the specified oral vehicle, humectant-solubilizer system, and anionic polymeric polycarboxylate.

Can a company sell a triclosan toothpaste without infringing US 4,894,220?

Yes, because the patent is expired. The product could still implicate later patents or regulatory restrictions, but not an enforceable right under US 4,894,220.

Does Gantrez in toothpaste create infringement risk under this patent?

No current risk exists because the patent is expired. Historically, Gantrez-type copolymer salts were directly relevant to claim 6 when used with the other claim 1 limitations.

Does the patent cover chlorhexidine mouthrinse?

Not literally under the claimed antibacterial group. The claims focus on substantially water-insoluble noncationic antibacterial agents selected from halogenated diphenyl ethers. Chlorhexidine is a different chemical class and is generally cationic.

Does FDA withdrawal of triclosan from antiseptic washes invalidate this patent?

No. FDA regulatory action and patent validity are separate issues. The patent expired independently, and FDA treatment depends on the specific product category and intended use.

References

United States Patent and Trademark Office. (1990). Antibacterial oral compositions (U.S. Patent No. 4,894,220).
United States Code. (2023). 35 U.S.C. § 154: Contents and term of patent; provisional rights.
U.S. Food and Drug Administration. (2016). Safety and effectiveness of consumer antiseptics; topical antimicrobial drug products for over-the-counter human use. Federal Register, 81 Fed. Reg. 61106.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Center for Drug Evaluation and Research.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	243371	⤷ Start Trial
Argentina	244259	⤷ Start Trial
Austria	119764	⤷ Start Trial
Austria	138557	⤷ Start Trial
Austria	150291	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Summary for Patent: 4,894,220