| PATENT GRANT DATE | September 16, 1997 |
| PATENT TITLE |
Coating composition for preparing solid preparations and solid preparations |
| PATENT ABSTRACT | The present invention provides a sugar coating composition comprising erythritol, a water-soluble cellulose, and an aqueous medium; and a solid preparation comprising a center core of a medicine or a food, etc. coated with the sugar coating composition. The sugar coating composition provides solid preparations with a smooth texture and satisfactory taste and which has a low viscosity even at room temperature and is therefore easy to handle |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | July 12, 1996 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A coating composition, which comprises erythritol, a water-soluble cellulose, and an aqueous medium. 2. A coating composition according to claim 1, wherein said water-soluble cellulose is a hydroxylalkyl group-containing water-soluble cellulose. 3. A coating composition according to claim 2, wherein said hydroxylalkyl group-containing water-soluble cellulose is a hydroxyalkylalkylcellulose. 4. A coating composition according to claim 3, wherein said hydroxyalkylalkylcellulose has a hydroxyalkyl group having 1 to 4 carbon atoms in the alkyl moiety thereof. 5. A coating composition according to claim 4, wherein the hydroxyalkyl moiety of said hydroxyalkylalkylcellulose is a 2-hydroxyalkyl group having 2 to 4 carbon atoms. 6. A coating composition according to claim 3, wherein the alkyl moiety other than the alkyl moiety of the hydroxyalkyl group is a methyl group. 7. A coating composition according to claim 3, wherein the hydroxyalkylalkylcellulose is hydroxypropylmethylcellulose. 8. A coating composition according to claim 1, wherein said composition has a water-soluble cellulose content of 1 to 10% by weight and an erythritol content of 10 to 50% by weight based on the total weight of the coating composition. 9. A coating composition according to claim 8, wherein said composition has a water-soluble cellulose content of 5 to 10% by weight, an erythritol content of 20 to 30% by weight based on the total weight of the coating composition, and a water-soluble cellulose to erythritol weight ratio of 1:2 to 1:7. 10. A solid preparation which comprises a center core of a medicine or a food and a surface coated layer comprising erythritol and a water-soluble cellulose. 11. A solid preparation according to claim 10, wherein the weight ratio of the surface coated layer to the center core is from 1:100 to 300:100. 12. A solid preparation according to claim 10, wherein the weight ratio of the surface coated layer to the center core is from 5:100 to 100:100. |
| PATENT DESCRIPTION |
FIELD OF THE INVENTION This invention relates to a sugar coating composition for preparing solid preparations such as powders, granules, tablets, etc. in the field of foodstuffs and pharmaceuticals; and solid preparations coated with the sugar coating composition. More particularly, it relates to non-hygroscopic solid preparations having a satisfactory texture and a sugar coating composition which is low in calories, does not cause dental caries, and has excellent handling properties in the coating operation. BACKGROUND OF THE INVENTION Bitter medicines, foods which are apt to change their shape with temperature rise, etc. have been supplied after forming a coating layer with a sugar coating composition so as to be taken or eaten with ease. Most of the conventional sugar coating compositions consist mainly of sugar, a binder, and water. Improvements have been added to these compositions in taste and adhesion to the center core to be coated which contains a medicine or a food material (hereinafter inclusively referred to as a "center"). As the binder used in the conventional sugar coating compositions to enhance adhesion of the coating layer to the center, gelatinizers such as gelatin and agar and gums such as gum arabic, xanthane gum, and guar gum have been widely used. For example, JP-A-62-5910 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") discloses a sugar coating composition containing hydroxypropylmethylcellulose and a water-soluble cellulose derivative as binders and sucrose, and JP-A-2-138117 discloses a sugar intermediate coating layer comprising hydroxypropylmethylcellulose and mannitol. Although gelatin has satisfactory binding properties, sugar-coated tablets prepared by using gelatin undergo reduction in disintegrability and also browning of color with the passage of time. While excellent in extending properties, gum arabic has insufficient binding properties. If used in an increased amount, the texture becomes rough when dried. Water-soluble cellulose as a binder, when coated on a center to form sugar-coated tablets, provides a smooth texture. However, water-soluble cellulose itself is unpleasant to the taste and has been limited in use. Further, there is a problem that the viscosity of the sugar coating composition prepared by using these conventional binders increases when it is applied to a center, making the coating operation difficult. In addition, the multi-layered structure in order to achieve good adhesiveness of the sugar coating layer and good texture results in too large sugar-coated preparations. SUMMARY OF THE INVENTION The inventors have conducted extensive study on the preparation of a sugar coating composition which is free from these disadvantages. As a result, they have found that a sugar coating composition using erythritol and water-soluble cellulose shows advantageous for handling in coating operation due to its low viscosity and provides coated solid preparations having a smooth texture and satisfactory adhesion between the sugar coat and the center, which can make the sugar coating layer thin. The present invention was accomplished based on these findings. That is, the gist of the present invention resides in a sugar coating composition comprising an aqueous medium, erythritol and a water-soluble cellulose, and in a coated solid preparation comprising a center core of a medicine or a food material coated with the sugar coating composition. DETAILED DESCRIPTION OF THE INVENTION The invention is described below in detail. The term "coated solid preparation" as used herein is intended to inclusively mean centers having a sweet taste surface layer. The coated solid preparations include pharmaceutical coated solid preparations, coated confectioneries or foods. Erythritol is a kind of tetrose alcohols, which is easily soluble in water and ready to crystallize to provide beautiful white crystals. It has 75 to 85% of the sweetness of sucrose and feels fresh and cool in the mouth. Erythritol rarely undergoes browning with time or increase in temperature, and it is low in calories and non-hygroscopic. The erythritol content in the sugar coating composition is subject to variation depending on the kind or quality of the center to be coated and is decided accordingly. For assuring satisfactory adhesion to the center and a good texture, it is preferably 10 to 50% by weight, still preferably 20 to 30% by weight, based on the total weight of the sugar coating composition. The water-soluble cellulose used in the present invention is obtained by partially or wholly etherifying the hydroxyl group of natural cellulose with organic chloride (e.g., alkali chloride, hydroxyalkyl chloride, aminoalkyl chloride) to form ether structures, and its appearance is white or yellowish white powder. Examples of the etherified substituents include alkyl groups (e.g., methyl and ethyl), hydroxyalkyl groups (e.g., hydroxymethyl and hydroxyethyl), aminoalkyl groups, and hydroxyaminoalkyl groups. The water-soluble cellulose may have one or more types of the above-described substituents. As the water-soluble cellulose, partially etherified ones are preferred. The degree of substitution is appropriately decided depending on the type of the substituents. As the water-soluble cellulose, hydroxyalkyl group containing water-soluble cellulose is preferable, and hydroxyalkylalkylcellulose (i.e., cellulose derivatives having hydroxyalkyl side groups and alkyl side groups) is particularly preferable. As the hydroxyalkylalkylcellulose, those having the hydroxyalkyl group having 1 to 4 carbon atoms in the alkyl moiety thereof with the alkyl group being methyl are preferable, and hydroxypropylmethylcellulose (referred to as "HPMC" hereinafter) is particularly preferable. The most preferred HPMC is 2-hydroxypropylmethylcellulose. HPMC is derived from cellulose by etherifying the hydroxyl group thereof with hydroxypropyl chloride and methyl chloride. The preferred hydroxypropyl group content of HPMC is in the range of from 4 to 12, more preferably from 7 to 12% by weight, and the preferred methyl group content of HPMC is in the range of from 20 to 30, more preferably from 28 to 30% by weight based on the natural cellulose used for the etherification. The water-soluble cellulose content in the sugar coating composition is arbitrarily selected according to the kind of the center to be coated. In order to assure satisfactory adhesion to the center, it is preferably 1 to 10% by weight, still preferably 5 to 10% by weight, based on the total weight of the sugar coating composition. If the water-soluble cellulose content is less than 1%, the composition tends to have insufficient adhesion. The too high water-soluble cellulose content is not preferable, since the water-soluble cellulose has a tendency to swell and gel on water absorption, which causes increase in the viscosity of the sugar coating composition, requires an extended period of time of the coating operation and, in some cases, causes water-soluble cellulose precipitates which provide coated solid preparations having a rough texture. It is particularly desirable for the sugar coating composition to have an erythritol content of 20 to 30% by weight and a water-soluble cellulose content of 5 to 10% by weight, based on the total weight of the sugar coating composition, with the weight ratio of water-soluble cellulose to erythritol being 1:2 to 1:7. In this embodiment, coated solid preparations extremely excellent in both adhesion and texture can be obtained. Crystal growth of erythritol in the coating operation may be controlled by using another sugar alcohol in combination with erythritol in such an amount that does not impair the non-hygroscopicity of erythritol. Usable sugar alcohols include maltitol, sorbitol, xylitol, and reducing saccharified starch. The amount of another sugar alcohol is preferably 1 to 100 parts by weight based on 100 parts by weight of erythritol. If desired, the sugar coating composition may further contain other sugars, such as sucrose, lactose, maltose, xylose, coupling sugar, and palatinose, as far as the characteristics of the composition, such as non-hygroscopicity, are not impaired. The medium of the sugar coating composition is an aqueous medium, usually water. If desired, the sugar coating composition may contain other binders, such as dextrin, starch, gelatin, other cellulose derivatives, polyvinyl alcohol, etc. in addition to water-soluble cellulose. Where a white coated solid preparation is desired, starch (e.g., potato starch, corn starch, wheat starch, and rice starch), calcium carbonate, talc, or titanium oxide may be dispersed in the sugar coating composition. The material and weight of the center can be arbitrarily chosen according to the object. For example, in the preparation of medicines in the form of granules, powders, pills or tablets or coated confectioneries, such as sugar-coated chewing gum, sugar-coated chocolate, spherical or disk-shaped centers each weighing about 0.1 to 3 g and measuring about 1 to 10 mm in diameter are generally used. The solid preparation according to the present invention includes the resulting sugar-coated tablets, film-coated tablets, coated confectioneries, as well as all the other coated materials having surface layer tasting sweetness. The step of coating centers with the sugar coating composition of the present invention can be carried out in a conventional manner. For improved workability, the sugar coating composition is preferably maintained at a temperature of from 10.degree. to 40.degree. C. during the coating operation. If the temperature exceeds 40.degree. C., water-soluble cellulose tends to precipitate and would make the texture of the resulting coated solid preparations rough. Therefore, the coating is preferably conducted at a temperature of not higher than 40.degree. C. The coating step is carried out by, for example, putting centers in a rotating container, and adding the sugar coating composition either intermittently or continuously in small portions while rotating the container. The amount of the sugar coating composition to be added is adjusted appropriately according to the surface area of the centers and the object of the coated solid preparations. The sugar coating composition of the present invention may also be sprayed to the center. After uniform application of the sugar coating composition to the surface of the centers, drying is carried out usually in the rotating container. Drying is carried out by blowing air at a temperature of 20.degree. to 80.degree. C., a relative humidity of 35 to 65%, and a rate of 2 to 8 m/sec. Once the sugar coated layer is dried, the sugar coating composition is again scattered thereon, followed by drying. The application of the composition and the drying are repeated several times to obtain resulting coated solid preparations. If desired, the resulting coated solid preparations may be given a gloss finish by addition of wax, shellac, etc. The amount of the dry coated layer may appropriately be decided depending on the density of the center and coated layer, and is generally from 0.1 to 500 parts by weight, preferably from 1 to 300 parts by weight, and more preferable from 5 to 100 parts by weight, based on 100 parts by weight of the center. The coated layer in an amount less than 0.1 part by weight is not preferable, since sufficient coating of the center would not be achieved or, when the center has undesirable taste (e.g., bitter), the sufficient improvement of the taste of the center by coated layer would not be achieved. The coated layer exceeding 500 parts by weight is not preferable, since the resulting sugar-coated preparation becomes too large. The sugar-coated preparations thus obtained have a weight of from about 0.1 g to about 10 g and a diameter of from about 1 mm to about 50 mm. The present invention will now be illustrated in greater detail with reference to Examples, but it should be understood that the present invention is not construed as being limited thereto as long as it does not depart from the gist of the present invention. The centers used in the following Examples were prepared by mixing 30 parts by weight of erythritol (hereinafter abbreviated as ET) and 70 parts by weight of lactose and molding the mixture by a tabletting machine. The viscosity (unit: cP) of the sugar coating compositions prepared was measured with an E type viscometer manufactured by Tokyo Keiki K. K. at 25.degree. C. All the numbers used for the constituents mean percents by weight based on the total sugar coating composition. The compositions having a zero content of water-soluble cellulose or ET are for comparison. Unless otherwise indicated, all parts, ratios, percents, and the like are by weight. |
| PATENT EXAMPLES | This data is not available for free |
| PATENT PHOTOCOPY | Available on request |
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