Details for Patent: 5,156,835
Summary for Patent: 5,156,835
| Title: | Antibacterial antiplaque oral composition | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Abstract: | An oral composition such as a dentifrice or mouthwash, containing an aqueous phase of water and as solubilizing agent propylene glycol, dipropylene glycol, methyl cellosolve, ethyl cellosolve, olive oil, castor oil, amyl acetate, ethyl acetate, glyceryl tristearate or benzyl benzoate mixed with at least one of glycerine and sorbitol, a substantially water-insoluble noncationic antibacterial antiplaque agent, such as 2,4,4'-trichloro-21 -hydroxydiphenyl ether (triclosan) or hexyl resorcinol and a synthetic anionic linear polymeric polycarboxylate having a molecular weight of about 1,000 to about 1,000,000. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Inventor(s): | Nuran Nabi, Abdul Gaffar | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assignee: | Colgate Palmolive Co | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Application Number: | US07/744,656 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Patent Claim Types: see list of patent claims | Use; Composition; Delivery; | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Patent landscape, scope, and claims: | United States Patent 5,156,835: Scope, Claims, Expiration, and Oral-Care Patent LandscapeU.S. Patent No. 5,156,835 covers oral dentifrices, mouthrinses, and plaque-control methods combining a substantially water-insoluble, noncationic phenolic antibacterial agent with a synthetic anionic polymeric polycarboxylate and a solubilizing agent. The patent’s central technical requirement is a formulation that keeps the phenolic antibacterial dissolved during dilution with saliva while using the polycarboxylate to improve delivery, tooth-surface adherence, and retention. The patent is expired. Its composition, formulation, and method claims therefore do not create a current U.S. blocking right, although the claimed technology remains relevant for freedom-to-operate analysis against later patents covering specific ingredients, formulations, manufacturing processes, or branded products. What does U.S. Patent 5,156,835 protect?The patent protects oral-care compositions and preparation or treatment methods containing four core elements:
The independent composition claims cover both dentifrices and mouthrinses. The method claims cover preparation of the dentifrice and inhibition of plaque formation by applying the claimed composition to oral surfaces. The specification’s functional limitation is important. The patent does not merely require the presence of a solvent. The solubilizing agent must dissolve the phenolic antibacterial compound and prevent its precipitation during oral dilution. Core claim architecture
What are the key limitations in independent claim 1?Claim 1 is the principal dentifrice composition claim. A potentially infringing product would need to satisfy each required limitation, including:
The claim is composition-based but includes functional limitations. Those limitations could create disputes over testing methodology, precipitation behavior, and whether the polycarboxylate materially improves retention rather than merely being present in the formula. Claim 1 risk pointsThe most commercially significant limitations are:
A formula using a different antibacterial class, such as a cationic bisbiguanide or quaternary ammonium compound, would generally fall outside the literal antibacterial-agent limitation. A formula using a nonpolymeric surfactant instead of the claimed polycarboxylate would also be outside the literal polymer limitation. Which antibacterial agents are covered?Claims 4, 19, and 20 narrow the antibacterial agent to four named phenolic compounds:
Claim 20 narrows the combination further to:
The broader claims use the functional and structural category of a “substantially water insoluble noncationic phenolic compound antibacterial agent.” The narrower claims provide clearer boundaries and are more readily evaluated against a commercial formula. Antibacterial-agent scope
The claims do not cover every antiplaque active. The claim language excludes cationic antibacterial agents by requiring a noncationic phenolic compound. It also requires substantial water insolubility, which may create a factual issue for compounds whose solubility varies by pH, salt form, solvent system, or formulation conditions. What polymeric polycarboxylates are protected?The broad claims cover a synthetic anionic polymeric polycarboxylate having a molecular weight from about 1,000 to about 1,000,000 and present at about 0.005% to 4% by weight. Claims 5 and 23 narrow the polymer to a water-soluble alkali-metal or ammonium salt of a copolymer of:
The narrowed molecular-weight range is about 30,000 to 500,000. Claim 20 further specifies a 1:4 to 4:1 copolymer ratio. This polymer is commonly associated with the Gantrez family of methyl vinyl ether/maleic anhydride or maleic acid copolymers. The claims, however, are drafted around chemical identity and formulation function rather than a commercial brand name. Polycarboxylate claim hierarchy
A product using a chemically different anionic polymer may avoid the narrower copolymer claims but could still raise issues under the broader polycarboxylate claims, depending on whether it meets the structural and molecular-weight limitations. What solubilizers are covered?Claim 18 lists the principal solubilizing-agent alternatives:
The claim requires the solubilizer to perform a technical function. Mere presence of propylene glycol or another listed material is not necessarily sufficient if the material does not dissolve the antibacterial agent and prevent precipitation during saliva dilution. Claim 20 creates a particularly defined formulation combination: hexyl resorcinol, the specified vinyl methyl ether/maleic copolymer, and propylene glycol. Solubilizer-related design-around optionsA formulator seeking to avoid the narrowest claims could consider:
The last option requires careful analysis because the claims expressly require dissolution and prevention of precipitation. A formulation that uses a stable suspension rather than a true solution may present a substantial distinction, subject to claim construction and equivalents analysis. How do claims 2-14 narrow the dentifrice?Claims 2-14 add conventional dentifrice features and specific concentration ranges.
Claim 13 is commercially specific. It targets a toothpaste or gel containing approximately:
Claims 6-9 and 24-26 extend the technology to anticalculus and fluoride-containing products. These limitations narrow the claims but also make them more relevant to conventional therapeutic toothpaste products. What does the mouthrinse coverage include?Claim 15 covers a mouthrinse containing:
Claim 16 specifies ethanol. Claim 17 specifies propylene glycol at about 5%-20%. Claims 23-26 add the narrower vinyl methyl ether/maleic copolymer, anticalculus polyphosphate, tetrasodium pyrophosphate, and fluoride limitations. The mouthrinse claims are structurally distinct from the dentifrice claims. They do not require polishing material. A mouthrinse would instead be assessed against the water/alcohol range, the active, polycarboxylate, and solubilization requirements. Mouthrinse claim vulnerabilitiesThe mouthrinse claims require a relatively high water/alcohol vehicle content and a defined water-to-alcohol ratio. Products using:
may avoid literal infringement of claim 15, depending on the complete formula. How broad are the method claims?Claim 21: preparation methodClaim 21 covers the preparation of a dentifrice by employing:
The method claim is directed to formulation manufacture rather than use. It may be relevant to a contract manufacturer, finished-product manufacturer, or ingredient supplier if the claimed steps are practiced in the United States. Claim 22: plaque-inhibition methodClaim 22 covers a method of inhibiting plaque formation by applying the claimed dentifrice to oral surfaces. It incorporates the same core formulation restrictions as claim 1. The claim does not broadly cover plaque reduction using any oral-care product. It requires the full combination of active, polycarboxylate, solubilizer, water-humectant phase, and polishing material. When did U.S. Patent 5,156,835 lose exclusivity?U.S. Patent 5,156,835 is expired. The patent was issued on October 20, 1992. As a pre-1995 U.S. patent, its ordinary term was generally 17 years from issue, producing an expected expiration in October 2009, absent a patent-term adjustment, terminal disclaimer, or other prosecution-specific modification. The U.S. patent term framework is governed by 35 U.S.C. § 154, with transitional rules for patents issued from older applications (U.S. Patent and Trademark Office, n.d.-a). Exclusivity timeline
The patent’s expiration means the claims cannot presently block a U.S. competitor from practicing the claimed composition or method. Later patents may still matter if they claim specific improvements, branded products, delivery systems, or manufacturing processes. Is U.S. Patent 5,156,835 listed in the Orange Book?No Orange Book listing should be expected for this patent. The patent claims oral-care compositions and plaque-inhibition methods rather than an FDA-approved prescription drug product. The FDA Orange Book primarily identifies patents and regulatory exclusivities associated with approved drug products and abbreviated new drug application certifications. A formulation patent for toothpaste or mouthrinse generally does not obtain Orange Book protection merely because the product contains an antibacterial active or fluoride source (U.S. Food and Drug Administration, n.d.). FDA regulatory statusThe claims do not establish FDA approval. They describe compositions and methods. Regulatory status depends on the finished oral-care product, its active ingredients, intended use, labeling, concentration, and applicable FDA monograph or new-drug requirements. The patent itself does not create:
Were Paragraph IV challenges relevant?Paragraph IV certifications apply to abbreviated new drug applications referencing an FDA-approved drug product with an Orange Book-listed patent. U.S. Patent 5,156,835 is not the type of patent ordinarily used as an Orange Book-listed pharmaceutical patent, and its expiration removes any current Paragraph IV barrier. A company commercializing a generic or private-label toothpaste would instead face:
What patent landscape surrounds the claimed technology?The relevant landscape has four technical clusters:
The patent’s commercial importance lies in the combination rather than in any single ingredient. Hexyl resorcinol, propylene glycol, silica, fluoride, and tetrasodium pyrophosphate are individually familiar oral-care materials. The claimed combination addresses a formulation problem: maintaining a substantially water-insoluble phenolic antibacterial in solution and improving its retention on oral surfaces. Adjacent patent categories
How strong was the patent estate?The patent had meaningful historical scope but a limited current asset value because all claims are expired. Historical strengths
Historical weaknesses
Current strengthThe current blocking strength is zero because the patent has expired. Its remaining value is technical and historical:
Are biosimilar risks relevant?No. Biosimilar risk is not relevant to this patent. U.S. Patent 5,156,835 covers small-molecule oral-care compositions and methods, not a biologic drug or therapeutic protein. The competitive risk is generic and private-label substitution in toothpaste and mouthrinse markets, not biosimilar entry under the Biologics Price Competition and Innovation Act. Which companies are likely to be relevant competitors?The commercial landscape for products that could practice or improve the claimed technology includes:
The patent record provided does not establish that any specific company currently markets a product practicing every limitation of the claims. Company-level infringement conclusions require product-formula evidence, not ingredient-category comparisons. Competitive product categories
What generic launch scenarios exist?Because the patent is expired, a generic or private-label manufacturer faces no launch delay attributable to U.S. Patent 5,156,835. Scenario 1: Direct practice of claim 20A toothpaste containing hexyl resorcinol, a specified methyl vinyl ether/maleic copolymer, and propylene glycol could practice the claim combination, but the expired patent would not support an infringement action. Scenario 2: Modern antiplaque formulationA product using a different active class, such as a cationic antibacterial, would generally avoid the literal phenolic limitation and would also be outside the patent’s central technical combination. Scenario 3: Reformulated delivery systemA product using a different adhesion polymer or a nonpolycarboxylate delivery system would reduce overlap with the broad claims. Scenario 4: Mouthrinse launchA mouthrinse using ethanol and propylene glycol could resemble claims 15-18, but expiration eliminates patent-based launch risk from this patent. What manufacturing and IP barriers remain?The expired patent does not remove all barriers. Current risks may arise from later patents covering:
Manufacturing evidence is especially important because claim 21 focuses on employing the polymer and solubilizer during preparation. A later patent could claim a particular hydration sequence, temperature, mixing order, or pre-dissolution step even though the composition itself is no longer protected by this patent. What geographic coverage did the patent provide?U.S. Patent 5,156,835 provided territorial protection only in the United States. Corresponding foreign rights, if any, would have required separate national or regional patents and separate term analysis. The U.S. expiration does not establish the status of:
A family-level search is necessary before relying on the U.S. expiration for global commercialization decisions. The claims supplied identify the U.S. scope but do not establish foreign-family status. What is the practical freedom-to-operate conclusion?For the United States, U.S. Patent 5,156,835 is a historical, expired patent and does not presently restrict commercialization of:
The patent remains useful for identifying the elements of a legacy formulation platform. A current freedom-to-operate review should focus on later patents claiming specific commercial implementations, improved solubilization systems, polymer grades, manufacturing processes, and therapeutic or cosmetic uses. Key Takeaways
FAQsDoes U.S. Patent 5,156,835 cover triclosan toothpaste?Not expressly. The claims require a substantially water-insoluble, noncationic phenolic antibacterial agent. Whether triclosan satisfies every limitation would require a separate claim-construction and formulation analysis, but the patent is expired in any event. Can a company sell a hexyl-resorcinol toothpaste in the United States?Yes, U.S. Patent 5,156,835 does not presently block sale because it is expired. The product must still satisfy applicable FDA requirements and avoid later enforceable patents. Does the patent cover sodium fluoride by itself?No. Sodium fluoride appears as a dependent limitation in claim 9. It is covered only in a composition that also satisfies the incorporated limitations of the relevant parent claim. Is Gantrez polymer still patent-protected because it appears in this patent?Not by this patent. The patent’s Gantrez-type polymer claims expired with the patent. Separate later patents may cover particular grades, combinations, uses, or manufacturing processes. Could the expired patent be cited against a later patent application?Yes. Its disclosure and claims may be relevant prior art against later applications seeking claims that substantially overlap its disclosed phenolic antibacterial, polycarboxylate, and solubilizer combination. References
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Drugs Protected by US Patent 5,156,835
| Applicant | Tradename | Generic Name | Dosage | NDA | Approval Date | TE | Type | RLD | RS | Patent No. | Patent Expiration | Product | Substance | Delist Req. | Patented / Exclusive Use | Submissiondate |
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| >Applicant | >Tradename | >Generic Name | >Dosage | >NDA | >Approval Date | >TE | >Type | >RLD | >RS | >Patent No. | >Patent Expiration | >Product | >Substance | >Delist Req. | >Patented / Exclusive Use | >Submissiondate |
International Family Members for US Patent 5,156,835
| Country | Patent Number | Estimated Expiration | Supplementary Protection Certificate | SPC Country | SPC Expiration |
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| 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 |
