Abstract:
An oral composition comprises triclosan, an alkyl sulfate and a water-soluble tin salt, whereby triclosan can be stably formulated to exert its effect.

Description:
BACKGROUND OF THE INVENTION 
     1. Industrial Field 
     The present invention relates to an oral composition which comprises triclosan (2,4,4&#39;-trichloro-2&#39;-hydroxydiphenyl ether) and more particularly, to an oral composition wherein the lowering in activity of triclosan by surface active agents can be prevented and the germicidal activity of triclosan is shown to a satisfactory extent. 
     2. Prior Art 
     It is known that oral compositions such as dentifrice which comprise triclosan as an effective ingredient can inhibit the formation of dental plaque because of the intense germicidal action of triclosan. In fact, there has been proposed incorporation, in oral compositions comprising triclosan, of zinc salts (Japanese Laid-open Patent Application Nos. 60-239409 and 3-127719, and Japanese Patent Publication No. 64-10489), copper compounds (Japanese Laid-open Patent Application No. 62-89614), polyethylene glycol (Japanese Laid-open Patent Application No. 62-126116), and the like. 
     However, when triclosan and a surface active agent such as alkyl sulfates ordinarily used as a foaming agent are used in combination, the germicidal activity is considerably lowered, with the problem that the effect of triclosan is not shown satisfactorily. In order to solve this problem, the present applicant already proposed the formulation of phenolic compounds (Japanese Laid-open Patent Application No. 2-11511) or water-soluble calcium salts (Japanese Laid-open Patent Application No. 3-5416) in an oral composition which comprises triclosan and a surface active agent. More effective measures for the dissolution are desirable. 
     It is essential to add a surface active agent to an oral composition such as dentifrice in order to make foams on use and to improve the feel in use. In particular, alkyl sulfates which are anionic surface active agents are most widely employed for this purpose. However, it presents a serious problem that triclosan which is added to oral compositions is impeded in activity by means of surface active agents. There is a demand of inhibiting the lowering in the activity of triclosan by surface active agents. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an oral composition containing triclosan in combination with an alkyl sulfate in which triclosan can be stably formulated to exert its effect, thereby preventing the formation of dental plaque and the occurrence of gingivitis. 
     We made intensive studies and, as a result, found that when a water-soluble tin salt is added to an oral composition which comprises triclosan and an alkyl sulfate surface active agent, the triclosan can be stably formulated in the composition comprising the alkyl sulfate surface active agent whereby the germicidal activity of triclosan can be effectively inhibited from lowering and shows its intense germicidal activity effectively. 
     As will become apparent from experiments described later, such an effect as set forth above is not produced when sparingly soluble or insoluble tin salts such as stannous pyrophosphate are added to oral compositions which comprise both triclosan and alkyl sulfates, but is developed only when water-soluble tin salts are added. Moreover, any stable composition is not obtained when water-soluble tin salts are added to triclosan and alkyl ether sulfates. Unexpectedly, we have found that when trichlosan, alkyl sulfates and water-soluble salts are used in combination, triclosan is stabilized. The invention is accomplished based on the finding that the stabilization of trichlosan results from a combination of these three ingredients. 
     It is known to formulate either alkyl sulfate surface active agents or water-soluble tin salts to triclosan-containing oral compositions (Japanese Laid-open Patent Application Nos. 62-89614 and 3-127719). Nevertheless, it is our finding that when triclosan, an alkyl sulfate surface active agent an a water-soluble tin salt are used in combination, a significant synergistic effect is obtained. 
     Therefore, according to the present invention, there is provided an oral composition comprising triclosan (2,4,4&#39;-trichloro-2&#39;-hydroxydiphenyl ether), an alkyl sulfate and a water-soluble tin salt. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The oral composition of the invention may be used in the form of dentifrices such as toothpastes, toothpowders and liquid dentifrices, mouthwashes, gingiva-massage creams, liquid or paste regional ointments, troches, chewing gums and the like. The composition comprises, in combination, triclosan, an alkyl sulfate surface active agent and a water-soluble tin salt. 
     The amount of triclosan is not critical and is generally in the range of 0.001 to 1.0% by weight, preferably 0.01 to 0.5% by weight of the total weight of the oral composition. 
     The alkyl sulfate used as the surface active agent is one whose carbon chain has 8 to 18 carbon atoms, preferably 10 to 14 carbon atoms. Specific examples of the alkyl sulfate surface active agent include sodium lauryl sulfate, sodium myristyl sulfate and the like. 
     The amount of the alkyl sulfate is not critical and generally in the range of 0.01 to 10% by weight, preferably 0.1 to 5% by weight of the total weight of the composition. 
     The water-soluble tin salts may be either inorganic or organic so long as they can be formulated from the pharmaceutical standpoint. Specific examples include stannous fluoride, stannous chloride, stannous fluoride chloride, stannous acetate, stannous sulfate, stannous tartrate, stannous gluconate, stannous citrate and the like. Of these, stannous fluoride stannous chloride and stannous gluconate are preferred. 
     The amount of the water-soluble tin salt is not critical and is generally in the range of 0.01 to 10% by weight, preferably 0.1 to 2% by weight of the total weight of the composition. If the amount is less than 0.01% by weight, the lowering in the activity of triclosan in the composition may not be prevented. Over 5% by weight, the feel of the composition may be impeded. 
     Depending on the purpose and the type of composition, the oral composition of the invention may further comprise, aside from the above-stated ingredients, abrasives, binders, humectants, flavors and other effective ingredients in amounts not impeding the germicidal effect of triclosan. 
     Examples of the abrasive include calcium hydrogen phosphate dihydrate, calcium carbonate, calcium pyrophosphate, calcium sulfate, insoluble sodium metaphosphate, silicic anhydride, hydrous silicic acid, aluminosilicate, alumina, aluminum hydroxide, magnesium tertiary phosphate, magnesium carbonate, and synthetic resins, alone or in a mixture of two or more (generally in amounts of 10 to 90% by weight based on the total weight of the composition, particularly 20 to 60% by weight in the case of toothpaste). Examples of the humectant include sorbitol, glycerin, propylene glycol, 1,3-butylene glycol, polyethylene glycol, xylitol, maltitol, and lactitol, alone or in admixture of two or more (generally in amounts of 5 to 85% by weight based on the total weight of the composition). Examples of the binder include sodium carboxymethyl cellulose, carrageenan, sodium aliginate, polyacrylic acid and salts thereof, gums, polyvinyl alcohol, and hydroxyethyl cellulose, alone or in admixture of two or more (generally in amounts of 0.3 to 5% by weight based on the total weight of the composition). 
     Also included are sweeteners such as saccharin sodium, stevioside, neohesperidyl dihydrochalcone, taumatin, glycyrrhizin, perillartine, etc.; preservatives such as p-hydroxybenzoates, sodium benzoate, etc.; and other components. When p-hydroxybenzoates are used as preservatives, their amount should preferably be 0.2% by weight or less because more than 0.3% of p-hydroxybenzoates provides a stimulating taste, resulting in oral compositions of less pleasant feel. 
     Other forms of oral compositions may be prepared in a conventional manner using selected components for a particular form of composition. 
     The thus obtained compositions is received in suitable containers such as aluminum tubes, laminate tubes in which aluminum foil is plastic laminated on either surface, plastic tubes, bottles, aerosol containers, and the like before it is ready for use. 
     The composition of the invention should preferably be adjusted in pH to 5 to 6.5. Outside this range, the lowering in the activity of triclosan may not be prevented satisfactorily. 
     The oral composition of the invention is formulated with water-soluble tin salts, so that the lowering in activity of triclosan by an alkyl sulfate can be prevented and, thus, good plaque formation-inhibiting effect based on the intense germicidal action of triclosan is attained. The composition of the invention is effective in preventing paradentosis. 
     EXAMPLES 
     The invention is more particularly described by way of examples, which should not be construed as limiting the invention. 
     EXAMPLE 1 
     A test solution having the following formulation was prepared. 0.3 ml of Escherichia coli suspension with 1.0×10 8  CFU/ml was added to 2.7 ml of the test solution, followed by sterilization reaction on a water bath at 35° C. for one minute. After completion of the reaction, the test solution was diluted with a SCDLP medium (made by Nippon Pharm. Co., Ltd.) and a given amount was cultivated overnight on a SCDLP agar plate (made by Nippon Pharm. Co., Ltd.) to determine the number of viable bacteria. The evaluation was made according to the following standard. The results are shown in Table 1. 
     
         ______________________________________Formulation of test composition______________________________________Propylene glycol      4.0%D-sorbitol            20.0Triclosan             0.05Surface active agent  0.5(indicated in Table 1)Tin compound          0.1(indicated in Table 1)Phosphate buffer solution (10 mM)                 balanceTotal                 100.0%______________________________________ 
    
     
                       TABLE 1______________________________________Tri-     Surface active        LogNo.  closan   agent       Tin compound                               CFU   pH______________________________________1    --       --          --        8.2   5.52    --       sodium lauryl                     --        8.0   5.5         sulfate3    ◯         sodium lauryl                     --        8.0   5.5         sulfate4    --       sodium lauryl                     stannous  8.0   5.5         sulfate     fluoride5    --       sodium lauryl                     stannous  8.0   5.5         sulfate     pyrophosphate6    ◯         sodium lauryl                     stannous  4.6   5.5         sulfate     fluoride7    ◯         sodium lauryl                     stannous  6.9   5.5         sulfate     pyrophosphate8    ◯         Na lauryl ether                     --        8.0   5.5         sulfate9    ◯         Na lauryl ether                     stannous  7.8   5.5         sulfate     fluoride______________________________________ 
    
     As will be apparent from the results of Table 1, when triclosan was used in combination with the alkyl sulfate surface active agent, no germicidal activity was recognized (No. 3). However, when a water-soluble tin compound such as stannous fluoride is added to the combination of the triclosan and the alkyl sulfate surface active agent, the lowering in the germicidal activity of triclosan in the alkyl sulfate surface active agent can be suppressed (No. 6). This effect was not recognized when the water-insoluble tin compound (stannous pyrophosphate) was used in combination. 
     EXAMPLE 2 
     Toothpaste 
     
         ______________________________________Aluminum hydroxide   45.0%Gelling silica       2.0Sorbitol             25.0Sodium carboxymethyl cellulose                1.0Sucrose monopalmitate                1.0Sodium lauryl sulfate                1.5Sodium saccharin     0.2Ethanol              0.1Sodium benzoate      0.1Gelatin              0.1Triclosan            0.3Stannous fluoride    0.2Sodium phytate       0.5Flavor               1.0Water                BalanceTotal                100.0%______________________________________ 
    
     EXAMPLE 3 
     Toothpaste 
     
         ______________________________________Precipitated silica  25.0%Sorbitol             25.0Glycerin             25.0Polyvinyl pyrrolidone                1.0Sodium polyacrylate  1.0Lauryl polyglycerin ester                1.0Sodium lauryl sulfate                1.0Sodium saccharin     0.2Ethyl p-oxybenzoate  0.1Sodium hydroxide     0.1Triclosan            0.2Stannous fluoride    0.4Flavor               1.0Water                BalanceTotal                100.0%______________________________________ 
    
     EXAMPLE 4 
     Toothpaste 
     
         ______________________________________Precipitated silica  25.0Gelling silica       2.0Sorbitol             20.0Propylene glycol     2.5Sodium carboxymethyl cellulose                1.0Lauryl diethanol amide                1.0Sodium lauryl sulfate                1.5Sodium lauroyl sarcosinate                0.3Sodium saccharin     0.1Ethyl p-oxybenzoate  0.1Triclosan            0.05Stannous gluconate   0.3Gelatin              0.2Flavor               0.8Water                BalanceTotal                100.0%______________________________________ 
    
     EXAMPLE 5 
     Oral paste 
     
         ______________________________________Cetanol              10.0%Squalane             20.0Gelling silica       5.0Polyoxyethylene (40 mol)                0.1hydrogenated castor oilSorbitan monooleate  1.0Sodium lauryl sulfate                0.2Glycyrrhetinic acid  0.1Sodium saccharin     0.6Triclosan            0.3Stannous fluoride    0.1Flavor               0.6Water                BalanceTotal                100.0%______________________________________ 
    
     EXAMPLE 6 
     Oral paste 
     
         ______________________________________Liquid paraffin      15.0%Cetanol              10.0Glycerin             20.0Sorbitan monooleate  0.6Polyoxyethylene (40 mol)                5.0sorbitan monostearateSodium lauryl sulfate                0.1Sodium saccharin     0.5Benzetonium chloride 0.1Triclosan            0.2Stannous fluoride    0.05Flavor               0.5Water                BalanceTotal                100.0%______________________________________ 
    
     EXAMPLE 7 
     Mouthwash 
     
         ______________________________________Sorbitol             10.0%Ethanol              5.0Polyoxyethylene (60 mol)                0.1hydrogenated castor oilSucrose monopalmitate                0.2Sodium lauryl sulfate                0.05Sodium saccharin     0.2Sodium hydroxide     0.05Triclosan            0.05Stannous fluoride    0.15Flavor               0.6Water                BalanceTotal                100.0%______________________________________ 
    
     EXAMPLE 8 
     Troche 
     
         ______________________________________Lactose              97.0%Polyoxyethylene (60 mol)                0.2monostearateSodium lauryl sulfate                0.05Chlorhexidine        0.02(gluconic acid salt)Stevia extract       0.2Gelatin              0.4Triclosan            0.2Stannous gluconate   0.1Flavor               0.02Hydroxyethyl cellulose                BalanceTotal                100.0%______________________________________