GB1573356A - Oral compositions - Google Patents

Abstract

The oral hygiene composition contains, in addition to an oral excipient, at least one nitrogen-containing antibacterial antiplaque agent in the form of an antibacterial cationic quaternary ammonium compound and/or an antibacterial long-chain tertiary amine compound containing an alkyl radical having 12 to 18 C atoms, and mellitic acid or hexahydromellitic acid as an additive preventing staining.

Description

(54) ORAL COMPOSITIONS (71) We, COLGATE-PALMOLIVE COMPANY, a Corporation organised under the Laws of the State of Delaware, United States of America, of 300 Park Avenue, New York, New York 10022, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to antibacterial oral compositions for promoting oral hygiene, and to method of making such compositions.

Cationic antibacterial materials are well known in the art. See, for instance, the section on "Quaternary Ammonium and Related Compounds" in the article on "Antiseptics and Disinfectants" in Kirk-Othmer Encyclopedia of Chemical Technology, 2nd edition (Vol. 2, p. 632-635). Cationic materials which possess antibacterial activity (i.e. are germicides) are used against bacteria and have been used in oral compositions to counter plaque formation caused by bacteria in the oral cavity.

Among the most common of these antibacterial and antiplaque quaternary ammonium compounds is benzethonium chloride, also known as "Hyamine 1622" or diisobutylphenoxyethoxyethyl dimethyl benzy ammonium chloride. In an oral composition this material is highly effective in promoting oral hygiene by reducing formation of dental plaque and calculus, which is generally accompanied by a reduction in caries formation and periodontal diseases. Other cationic antibacterial agents of this type are those mentioned, for instance, in U.S. Patent Specifications 2,984,639, 3,325,402, 3,431,208 and 3,703,583, and British Patent Specification 1,319,396.

Other antibacterial antiplaque quaternary ammonium compounds include those in which one or two of the substituents on the quaternary nitrogen (typically an alkyl group) has a carbon chain length of about 8 to about 20, typically 10 to 18, carbon atoms, while the remaining substituents (typically alkyl) or benzyl groups) have a lower number of carbon atoms such as 1 to 7 carbon atoms, typically methyl or ethyl groups. Dodecyl trimerhyl ammonium bromide, dodecyl dimethyl (2phenoxyethyl) ammonium bromide, benzyl dimethyl stearyl ammonium chloride, cetyl pyridinium chloride and quaternized 5amino - 1,3 - bis(2 - ethyl - hexyl) 5- methyl hexahydropyrimidine are other typical quaternary ammonium antibacterial agents.

Long chain tertiary amines also possess antibacterial and antiplaque activity. Such antibacterial agents include tertiary amines having one fatty alkyl group (typically of from 12 to 18 carbon atoms) and two polyoxyethylene) groups attached to the nitrogen (typically containing a total of from 2 to 50 ethenoxy groups per molecule) and salts thereof with acids, and compounds of the structure:

wherein R represents a fatty alkyl group containing from 12 to 18 carbon atoms, and x, y and z total 3 or higher, as well as salts thereof.

Generally, cationic agents are preferred for their antiplaque effectiveness.

For use in antibacterial oral compositions the antibacterial antiplaque compound preferably has an antibacterial activity such that its phenol co-efficient is well over 50, more preferably well above 100, such as above 200 for S. aureus; for instance the phenol coefficient (A.O.A.C.) of benzethonium chloride is given by the manufacturer as 410, for S. aureus. For oral composition the cationic antibacterial agents generally are monomeric (or possibly dimeric) materials of molecular weight well below 2,000, such as less than 1,000.

However, polymeric cationic antibacterial agents are also effective. The cationic antibacterial is preferably employed in the form of an orally acceptable salt thereof, such as the chloride, bromide, sulphate, alkyl sulphonate such as methyl sulphonate or ethyl sulphonate, phenylsulphonate such as pmethylphenyl sulphonate, nitrate, acetate or gluconate.

The cationic quaternary ammonium and long chain tertiary amine antibacterial agents effectively promote oral hygiene, particularly by removing plaque. However, their use has been observed to lead to staining or discoloration of dental surfaces.

The reason for the formation of such dental stain has not been clearly established. However, human dental enamel contains a high proportion (about 95%) of hydroxyapatite which includes Ca+2 and PO,-S ions. In the absence of dental plaque additional Ca+2 and PO4-', particularly from saliva, can be deposited on the enamel and such deposits can include colour bodies which ultimately stain the tooth enamel as a calcified deposit thereon.

It may be that as the cationic quaternary ammonium or long chain tertiary amine antibacterial agents remove plaque they also denature protein from saliva in the oral environment and the denatured protein may then act as a nucleating agent which is deposited on and stains or discolours tooth enamel.

Previously employed additives which reduced dental staining by cationic antibacterial antiplaque agents also generally reduced the activity of the antibacterial agent or its ability to act on dental plaque to measurable degrees.

Further, "Victamide" (also known as "Victamine C") which is the condensation product of ammonia with phosphorus pentoxide actually increases staining even in the absence of a cationic antibacterial antiplaque agent, and it and other known phosphorus-containing agents such as disodium - ethane- 1 - hydroxy1,1 - diphosphonic acid salt precipitate in the presence of antibacterial agents such as a bisbiguanido compound, thereby reducing the antiplaque effectiveness of the antibacterial agent.

This invention provides an additive which prevents or inhibits staining of dental enamel without precipitating or substantially adversely affecting the antibacterial and antiplaque activity of cationic quaternary ammonium or long chain tertiary amine antibacterial agents.

In accordance with one aspect of this invention an oral composition comprises a vehicle, at least one antibacterial antiplaque agent selected from cationic quaternary ammonium antiplaque antibacterial agents and long chain tertiary amine antibacterial antiplaque agents containing a fatty alkyl group of from 12 to 18 carbon atoms, and as an antistain additive thereto mellitic acid (benzene hexacarboxylic acid) or hexahydromellitic acid (cyclohexane hexacarboxylic acid) or an orally acceptable salt of such acid or a mixture of any of these additives.

Examples of such additive salts are those containing alkali metal (e.g. sodium and potassium), ammonium, C1 18 mono-, di- and trisubstituted ammonium (e.g. alkanol substituted such as mono-, di- and tri-ethanolammonium) and amine cations. These additives in their free acid form are water-soluble, as are their orally acceptable salts.

The concentration of the antistain additive in the oral compositions can range widely, typically upwards from 0.005% by weight with no upper limit except as dictated by cost or incompatibility with the vehicle. Generally, concentrations from 0.005% to 10%, preferably from 0.01% to about 2%, by weight, are utilized. Oral compositions which in ordinary usage could be accidentally ingested preferably contain low concentrations of these additives. Thus, a mouthwash preferably contains less than 1% by weight of the additive.

Dentifrice compositions, topical solutions and prophylactic pastes, the latter to be administered professionally, preferably contain from 0.1% to 2%, by weight of the additive.

Most desirably, the antistain additive is present in a molar ratio relative to the amount of antibacterial antiplaque agent (based on its free base form) in the range from 0.2:1 to 6:1, preferably from 0.5:1 to 4:1.

Cationic quaternary ammonium and long chain tertiary amine antibacterial antiplaque agents which may be employed in the practice of this invention have been referred to above.

They are typically employed in amounts such that the composition contains from 0.001% to 15% by weight of the agent, based on its free base form. Preferably the compositions contain from 0.01% to 5%, most preferably from 0.025% to 1.0%, by weight, of the antibacterial agent, based on its free base form.

The stain which generally occurs on dental enamel is substantially or entirely prevented when the above-defined mellitic acid additives or orally acceptable water-soluble salts thereof are employed. These materials are antinucleating agents. In themselves (even in the absence of cationic antiplaque antibacterial agents) they are effective to reduce formation of dental calculus without unduly decalcifying enamel. However, not all anti-nucleating agents are effective to prevent stain by cationic antibacterial agents. For instance, "Victamide" actually increases staining even in the absence of an antibacterial antiplaque agent.

The oral compositions may be substantially liquid in character, such as a mouthwash or rinse. In such a composition the vehicle is typically a water-alcohol mixture. Generally, the ratio of water to alcohol is in the range from 1:1 to 20:1 preferably from 3:1 to 20:1 and most preferably about 17:3, by weight.

The total amount of water-alcohol mixture in this type of composition is typically in the range from 70% to 99.9% by weight of the composition.

The pH of the compositions of the inven tion is generally in the range from 4.5 to 9, typically from 5.5 to 8. The pH is prefer ably in the range from 6 to 8.0. It is note worthy that the compositions of the invention may be applied orally at a pH below 5 with out substantially decalcifying dental enamel.

Such liquid oral compositions may also contain a surface active agent and/or a fluorine-providing compound.

In other forms of the invention the oral compositions may be substantially solid or pasty in character, such as a toothpowder, a dental tablet, a toothpaste or dental cream.

The vehicle of such solid or pasty compositions contain dental polishing material. Examples of such polishing materials are water-insoluble sodium metaphosphate, potassium metaphos phate, tricalcium phosphate, dihydrated cal cium phosphate, anhydrous dicalcium phos phate, calcium pyrophosphate, magnesium orthophosphate, trimagnesium phosphate, cal cium carbonate, alumina, hydrated alumina, aluminium silicate, zirconium silicates, silica, bentonite, and mixtures thereof. Preferred polishing materials include crystalline silica having particles sizes of up to 5 microns, a mean particle size of up to 1.1 microns, and a surface area of up to 50,000 cm2/g, silica gel, complex amorphorus alkali metal alumino silicate and hydrated alumina.

Alumina, particularly the hydrated alumina sold by Alcoa (U.S.A.) as C333, which has an alumina content of 64.9% by weight, a silica content of 0.008%, a ferric oxide content of 0.003%, and a moisture content of 0.37 at 1100C, and which has a specific gravity of 2.42 and a particle size such that 100% of the particles are less than 50 microns and 84% of the particles are less than 20 microns, is particularly desirable.

When visually clear gels are employed, a polishing agent of colloidal silica, such as those sold under the trademark SYLOID as "Syloid 72" and "Svloid 74" or under the trademark SANTOCEL as "Santocel 100" and alkali metal aluminosilicate complexes are particularly useful, since they have refractive indices close to the refractive indices of gelling agent-liquid (including water and/or humectant) systems commonly used in dentifrices.

Many of the so called "water-insoluble" polishing materials are anionic in character and also include small amounts of soluble material. Thus, insoluble sodium metaphosphate may be formed in any suitable manner, as illustrated by Thorpe's Dictionary of Applied Chemistry, Volume 9, 4th Edition, pp. 510-511. The forms of insoluble sodium metaphosphate known as Madrell's salt and Kurrol's salt are further examples of suitable materials. These metaphosphate salts exhibit a minute solubility in water, and therefore are commonly referred to as insoluble metaphosphates. There is present therein a minor amount of soluble phosphate material as impurities, usually a few percent such as up to 4% by weight. The amount of soluble phosphate material, which is believed to include a soluble sodium trimetaphosphate in the case of insoluble metaphosphate, may be reduced by washing with water if desired. The insoluble alkali metal metaphosphate is typically employed in powder form of a particle size such that no more than 1% of the material is larger than 37 microns.

The polishing material is generally present in amounts ranging from 20% to 99% by weight of the composition. Preferably, it is present in amounts ranging from 20% to 75% in toothpaste, and from 70% to 99% in toothpowder.

In the preparation of toothpowders, it is usually sufficient to admix mechanically, e.g. by milling, the various solid ingredients in appropriate quantities and particle sizes.

In pasty oral preparations the above-defined combination of the antibacterial antiplaque agent and antistain additive should be compatible with the other components of the composition. Thus, in a toothpaste, the liquid vehicle may comprise water and humectant, typically in an amount ranging from 10% to 90% by weight of the composition. Glycerine, sorbitol, or polyethylene glycol may also be present as humectants or binders. Particularly advantageous liquid ingredients comprise mixtures of water, glycerine and sorbitol.

In clear gels where the refractive index is an important consideration, from 3% to 30% by weight of water, up to 80% by weight of glycerine, and from 20% to 80% by weight of sorbitol is preferably employed. A gelling agent, such as natural or synthetic gums or gum-like materials, typically Irish moss, sodium carboxymethylcellulose, methyl cellulose, or hydroxyethyl cellulose, may be employed.

Other gelling agents which may be employed include gum tragacanth, polyvinylpyrrolidone and starch. They are usually present in toothpaste in an amount up to 10% by weight, preferably in the range from 0.5% to 5%.

The preferred gelling agents are methyl cellulose and hydroxyethyl cellulose. In a toothpaste or gel, the liquids and solids are proportioned to form a creamy or gelled mass which is extrudable from a pressurized container or from a collapsible tube, e.g. an aluminium or lead tube.

The solid or pasty oral preparation which typically has a pH measured on a 20% slurry in the range from 4.5 to 9, generally from 5.5 to 8 and preferably from 6 to 8, may also contain a surface active agent and/or a fluorine-providing compound.

In oral compositions such as mouthrinses and toothpastes, a surfactant is often present, e.g. to promote foaming. In compositions embodying the present invention it is prefer able to employ nonionic surfactants rather than their anionic counterparts. Examples of water-soluble nonionic surfactants are condensation products of ethylene oxide with various compounds reactive therewith having long hydrophobic chains (e.g. aliphatic chains of 12 to 20 carbon atoms) which condensation products "ethoxamers") have hydrophilic polyoxyethylene moieties, such as condensation products of ethylene oxide and fatty acids, fatty alcohols and fatty amides, including alcohols such as sorbitan monostearate or polypropyleneoxide (e.g. materials sold under the trade mark PLURONIC).

In certain forms of this invention a fluorineproviding compound is present in the oral composition. These compounds may be slightly soluble in water or may be fully water-soluble.

They are characterized by their ability to release fluoride ions in water and by substantial freedom from reaction with other compounds of the oral composition. Among these materials are inorganic fluoride salts, such as soluble alkali metal, alkaline earth metal and heavy metal salts, for example, sodium fluoride, potassium fluoride, ammonium fluoride, lead fluoride, a copper fluoride such as cuprous fluoride, zinc fluoride, a tin fluoride such as stannic fluoride or stannous chlorofluoride, barium fluoride, sodium fluorsilicate, ammonium fluorsilicate, sodium fluorozirconate, sodium monofluorophosphate, aluminium mono- and di-fluorophosphate, and fluorinated sodium and calcium pyrophosphate. Alkali metal and tin fluorides, such as sodium and stannous fluorides, sodium monofluorophosphate and mixtures thereof, are preferred.

The amount of the fluorine-providing compound is dependent to some extent upon the type of compound, its solubility, and the type of oral composition, but it must be a nontoxic amount. In a solid oral composition, such as a toothpaste or toothpowder, an amount of such compound which releases a maximum of 1% of fluoride ion by weight of the composition is satisfactory. Any suitable minimum amount of such compound may be used, but it is preferable to employ sufficient compound to release from 0.005%, to 1%, and preferably about 0.1% of fluoride ion. Typically, in the cases of alkali metal fluorides and stannous fluoride, this component is present in an amount up to 2% by weight, based on the weight of the composition, and preferably in the range from 0.05% to 1%. In the case of sodium mono fluorophosphate, the compound may be present in an amount up to 7.6% by weight, more typically about 0.76%: In a liquid oral composition such as a mouthwash, the fluorine-providing compound is typically present in an amount sufficient to release up to 0.13%, preferably from 0.0013 to 0.1% and most preferably from 0.003% to 0.05%, by weight, of fluoride ion.

Various other materials may be incorporated in the oral compositions of this invention.

Examples are whitening agents, preservatives, silicones, chlorophyll compounds, and ammoniated materials such as urea and diammonium phosphate, and mixtures thereof. These adjuvants, where present, are incorporated in the compositions in amounts which do not substantially adversely affect the properties and characteristics desired.

Any suitable flavouring or sweetening material may also be employed. Examples of suitable flavouring constituents are flavouring oils, e.g. oils of spearmint, peppermint, wintergreen, sassafras, clove, sage, eucalyptus, marjoram, cinnamon, lemon, and orange, and methyl salicylate. Suitable sweetening agents include sucrose, lactose, maltose, sorbitol, perillartine and saccharine. Suitably, flavour and sweeteing agents may together constitute from 0.01% to 5% or more of the composition.

In preparing the oral compositions of this invention comprising the above-defined com bination of antibacterial agent and antistain additive in an oral vehicle which typically includes water, it is highly preferred although not essential to add the antistain additive after the other ingredients (except perhaps some of the water) are mixed or contacted with each other to avoid a tendency for the antibacterial agent to be precipitated.

For instance, a mouthrinse or mouthwash may be prepared by mixing ethanol and water with flavouring oil, nonionic surfactant, humec tant, cationic anti-bacterial antiplaque agent, such as benzethonium chloride or cetyl pyri dinium chloride, sweetener, colour and then the above-defined antistain additive, followed by additional water as desired.

A toothpaste may be prepared by forming a gel with humectant, gum or thickener such as hydroxyethyl cellulose, sweetener and add ing thereto polishing agent, flavour, anti bacterial agent, additional water, and then the above-defined antistain additive. If sodium carboxymethyl cellulose is employed as the gelling agent the procedure of either of U.S.

Patent Specifications 3,842,168 and 3,843,779, modified by the inclusion of the antistain additive, may be followed.

An oral composition embodying this inven tion, such as a mouthwash or toothpaste, con taining cationic quaternary ammonium or long chain tertiary amine antibacterial anti plaque agent in an amount effective to promote oral hygiene, and the defined antistain additive in an amount effective to reduce staining of dental surfaces otherwise resulting from the presence of the antibacterial antiplaque agent, may be applied regularly to dental enamel, preferably from 5 times per week to 3 times daily, at a pH in the range from 4.5 to 9, generally from 5.5 to 8, preferably from 6 to 8.

The following Examples illustrate the invention. All amounts and proportions are by weight. In the Examples, BC means benz- ethonium chloride, CPC means cetyl pyridinium chloride and MA means mellitic acid.

EXAMPLES 1 - 6 MOUTHWASH FORMULATIONS EXAMPLES (% by weight) (1) (2) (3) (4) (5) (6) Placebo Control Control Flavour 0.22 0.22 0.22 0.22 0.22 0.22 Ethanol 15.0 15.0 15.0 15.0 15.0 15.0 BC - 0.075 0.075 0.075 - CPC - - - - 0.1 0.1 PLURONIC F108* 3.0 3.0 3.0 3.0 3.0 3.0 Glycerine 10.0 10.0 10.0 10.0 10.0 10.0 MA - - 0.1 0.5 - 0.2 Water to pH 7.0 (with NaOH) 100 100 100 100 100 100 Appearance clear clear clear clear clear clear Reflectance 56 48 52 56 31 38 Reflectance difference - - 4 8 - 7 * polyalkene oxide block polymer The MA, and about 10 parts of the water, are added to the other previously mixed ingredients. Tooth staining characteristics are tested by slurrying hydroxyapatite "Biogel") with salivary protein and acetaldehyde and a pH7 phosphate buffer. The mixture is shaken at 37 C until a light brown colour develops.

Coloured powder is separated, dried and colour levels (in reflectance units) determined on a "Gardner Color Difference Meter" before and after the test composition is applied to the coloured material.

The above results establish that mellitic acid substantially reduces dental staining ordinarily produced by quatemary ammonium antibacterial antiplaque agents as exemplified by BC and CPC. Formulations adjusted to pH ranging from 5 to 8 yield similar results.

Orally acceptable salts of mellitic acid yield similar results. Further, tests for antiplaque activity vs. actinomyces viscosus indicate Examples 3 and 4 (BC and MA) to be equivalent to Control Example 2 (BC), and Example 6 (CPC and MA) to be equivalent to Control Example 5 (CPC).

Examples 7-9.

Substitution of equivalent amounts of hexahydro mellitic acid for the MA in Examples 3, 4 and 6 yields similar results.

Examples 10-12.

Similar results are obtained when the BC and CPC of Examples 3, 4 and 6 are replaced by an equivalent amount of the long chain tertiary amine antibacterial antiplaque agent of the formula:

Claims (10)

1. The following formulations exemplify toothpastes with antiplaque activity and reduced staining: Example (Parts)

   13 14 Hydrated alumina 30 30 Glycerine 16 16 Sorbitol (70 /,,) 6 6 PLURONIC F-108 3 3 Hydroxyethyl cellulose 1.2 1.2 Benzethonium chloride (BC) 0.5 - CPC - 4.725 MA 2 2 Sodium saccharin 0.17 0.17 Flavour 0.8 0.8 Water to 100 100 WHAT WE CLAIM IS:- 1. An oral composition comprising a vehicle, at least one antibacterial antiplaque agent selected from cationic quaternary ammonium antibacterial antiplaque agents and long chain tertiary amine antibacterial antiplaque agents containing a fatty alkyl group of from 12 to

   18 carbon atoms, and as an antistain additive mellitic acid or hexahydromellitic acid or an orally acceptable salt of such acid or a mixture of any of these additives.
2. 2. An oral composition according to Claim 1 wherein the antibacterial antiplaque agent is present in an amount from 0.001% to 15% by weight based on its free base form and the antistain additive is present in amount from 0.005% to 10% by weight.
3. 3. An oral composition according to Claim 2 wherein the antibacterial antiplaque agent is present in an amount from 0.01 to 5% by weight based on its free base form and the antistain additive is present in a molar ratio relative to the antibacterial antiplaque agent in the range from 0.2:1 to 6:1.
4. 4. An oral composition according to any of the preceding Claims wherein the antibacterial antiplaque agent is a Cm2~18 alkyl tertiary amine having the formula
5. 5. An oral composition according to any of Claims 1 to 3 wherein the antibacterial antiplaque agent is benzethonium chloride.
6. 6. An oral composition according to any of Claims 1 to 3 wherein the antibacterial antiplaque agent is cetyl pyridinium chloride.
7. 7. An oral composition according to any of the preceding Claims wherein the vehicle is an aqueous-alcohol, and which is a mouthwash of pH in the range from 4.5 to 9.
8. 8. An oral composition according to any of Claims 1 to 6 wherein the vehicle comprises a liquid component and a gelling agent, and a dentally acceptable polishing material is present, which composition is a toothpaste of pH in the range from 4.5 to 9.
9. 9. An oral composition substantially as described in any of Examples 3, 4 and 6 to 14.
10. 10. A method of preparing an oral composition according to any of Claims 1 to 8 wherein the antistain additive is added after the remaining components of the composition have been contacted with each other.