Bright white film coatings and film coating compositions therefor

[0002] The present application is a divisional of U.S. Ser. No. 08/895,484, filed Jul. 16, 1997, the contents of which is incorporated by reference herein in its entirety.

[0003] 1. Field of the Invention

[0004] This invention relates to the field of aqueous film coating of nutritional supplements and pharmaceutical tablets, and is specifically concerned with providing bright white film coatings based on dextrose for coating nutritional supplements, such as vitamin tablets and calcium/oyster shell tablets, and pharmaceutical tablets, such as acetaminophen (APAP), aspirin (ASA), and Ibuprofen.

[0005] 2. Description of the Prior Art

[0006] Hydroxypropyl methylcellulose (HPMC) has been used in coatings for substrates such as pharmaceutical tablets. For example, such coatings, including white coatings (coatings containing titanium dioxide as the colorant), made from coating compositions manufactured by Colorcon and disclosed in U.S. Pat. Nos. 4,543,370 and 4,683,256, said patents being incorporated herein by reference, have proven especially effective when used on pharmaceutical tablets.

[0007] However, in the pharmaceutical and nutritional supplement industries, it is desired to provide some pharmaceuticals, such as APAP and Ibuprofen, and some nutritional supplements with a white coating that is brighter than the white coatings obtained using HPMC-based coating compositions.

[0008] It is an object of the invention to provide a white film coating for vitamin tablets, calcium/oyster shell tablets, and pharmaceutical tablets that is brighter than the white film coatings obtained using HPMC-based coating compositions.

[0009] These and other objects are accomplished by our invention, which is described below.

[0010] In accordance with the invention, our dry film coating compositions for use in forming coating dispersions for film coating nutritional supplements, pharmaceutical tablets, and the like, comprise dextrose, an auxiliary film former, and titanium dioxide.

[0011] Advantageously, the inventive dry film coating compositions may include one or more of the following components: a plasticizer, a surfactant, a flow aid, and a preservative.

[0012] In accordance with the invention, a method of coating substrates such as nutritional supplements, pharmaceutical tablets, and the like, comprises mixing dextrose, an auxiliary film-former, and titanium dioxide into water to form an inventive aqueous coating dispersion, applying the inventive coating dispersion onto said substrates to form a white film coating on said substrates, and drying the white film coating on said substrates. Optionally, but advantageously, the following components may be mixed into water with the dextrose, the auxiliary film-former, and the titanium dioxide to form the inventive coating dispersion: a plasticizer, a surfactant, a flow aid, and a preservative.

[0013] The invention also includes the coated substrates, such as coated vitamins, coated calcium/oyster shell tablets, and coated pharmaceutical tablets, the aqueous coating dispersion formed from the inventive dry film coating composition or from the components of said composition, the method of making the dry film coating compositions and the method of making the coating dispersions of the invention.

[0014] The primary film-former of the inventive dry film coating composition and of the inventive aqueous coating dispersion is dextrose.

[0015] The preferred range for dextrose is about 20% to about 50% by weight of the inventive dry film coating composition and of the non-water ingredients of the inventive aqueous coating dispersion. More preferably, the range for dextrose is about 25% to about 35% by weight of the inventive dry film coating composition and of the non-water ingredients of the inventive aqueous coating dispersion.

[0016] The auxiliary film-former may be polyvinylpyrrolidone (PVP), hydroxypropyl methylcellulose, methylcellulose, hydroxypropyl cellulose (HPC), sodium carboxymethylcellulose (sodium CMC), maltodextrin, polydextrose, modified food starch, modified food starch with corn syrup solids, starch (e.g., STARCH 1500 starch), tapioca dextrin, lactose, sodium alginate, PG alginate, gum acacia, polyvinyl alcohol (PVA), any of the film coating polymers recited in Colorcon U.S. Pat. No. 4,543,370, which is incorporated herein by reference, and combinations thereof. The auxiliary film-former(s) act as strength enhancers for the film coating. Their presence in the coatings help prevent cracking of the film coating, as well as helping to prevent edge wear/chipping of the coated tablet. A preferred auxiliary film-former is sodium CMC. The preferred and the more preferred ranges for the auxiliary film-former(s) by weight of the inventive dry film forming composition and by weight of the non-water ingredients of the inventive aqueous coating dispersion are 1% to 50% (preferred) and 10% to 20% (more preferred). The preferred ranges and the more preferred ranges for various exemplary auxiliary film-former(s) are set out below.

[0017] The preferred range and the more preferred range for the titanium dioxide (TiO₂) are 25% to 50% (preferred) and 30% to 40% (more preferred) by weight of the inventive coating composition and by weight of the non-water ingredients of the inventive coating dispersion.

[0018] Exemplary of the plasticizer are mineral oil, polyethylene glycol having a molecular weight in the range of 200 to 8000, propylene glycol, glycerine, triacetin, acetyltriethyl citrate, triethyl citrate (Citroflex A2), tributylcitrate (Citroflex 4), and acetyltributylcitrate (Citroflex A4), and the preferred ranges for the plasticizer are set out below, together with preferred and more preferred ranges for various exemplary plasticizers.

[0019] Exemplary of the surfactant is Polysorbate 80, and the preferred ranges for the surfactant are set out below, together with preferred and more preferred ranges for an exemplary surfactant.

[0020] Exemplary of the flow aid is stearic acid, and the preferred ranges and the more preferred ranges for the flow aid are set out below, together with the preferred and the more preferred ranges for stearic acid.

[0021] Exemplary of the preservative is sodium citrate, and the preferred ranges for the preservative are set out below, together with the preferred and the more preferred ranges for sodium citrate.

[0022] The ranges set out above are all by weight of the dry film coating composition of the invention and of the non-water ingredients of the aqueous coating dispersion of the invention.

[0023] The following examples illustrate the invention, all ingredients being by weight.

[0024] The dry components of the following formulation were blended together for five minutes in a PK Blender (Paterson Kelly) to form a mixture. Then, the liquid components were added to the mixture of dry components via the I-bar of the blender and blended therein by mixing for an additional five minutes to form a dry film coating composition of the invention.

[0025] Optionally, the composition may be milled such as in a hammer mill (Apex Machinery, Dartford, England), for example.

[0026] Optionally, the dry film coating composition may be granulated using a planetary mixer, such as a Hobart planetary mixer. To accomplish this, the dry film coating composition is loaded into the mixer and the mixer is switched on, and sufficient water is slowly added until the composition forms slightly adherent granules. These granules are then passed through a 1-2 mm screen and then dried in a 30° C. oven until the moisture content is below 5%. The composition is then sieved again through a 1-2 mm screen and is then ready for use in a non-dusting, granular form. Other methods of granulation, such as spray granulation and roller compaction, also may be used.

[0027] 450 grams of the resulting film coating composition was dispersed into 1800 grams of distilled water (about 30 minutes) to form an inventive coating dispersion (20% solids), and all of the dispersion was sprayed using a 24″ Accela Cota coater (Thomas Engineering) onto 15000 grams of vitamin tablets (Pharmavite) to form an inventive coating thereon having a theoretical weight gain of 3.0%.

[0028] This produced a bright white film coating on the tablets.

[0029] Example 1 was repeated, except that the dispersion was sprayed onto 15000 grams of APAP tablets. This produced a bright white film coating on the APAP tablets.

[0030] Example 1 was repeated, except that the film coating composition had the following formulation:

[0031] This produced a bright white film coating on the tablets.

[0032] Example 2 was repeated, except that the film coating composition had the formulation of Example 3. This produced a bright white film coating on the APAP tablets.

[0033] The dry components of the following formulation were blended together for five minutes in a food processor to form a mixture. Then, the liquid components of the formulation were added to the mixture of the dry components and blended therein by mixing for an additional five minutes to form a film coating composition of the invention.

[0034] Optionally, the coating composition may be granulated or milled.

[0035] 9.0 grams of the resulting film coating composition was dispersed into 36.0 grams of distilled water and stirred until dispersed to form an inventive coating dispersion (20% solids), and all of the dispersion was sprayed using an Aeromatic Strea 1 coater (Niro) onto 300 grams of ⅜″ concave white placebos to form an inventive coating thereon having a theoretical weight gain of 3.0%.

[0036] This produced a bright white film coating on the tablets.

[0037] Examples 6-19 further illustrate the invention, all percentages being by weight. In Examples 6-19, the components of each formulation are mixed together, formed into a coating dispersion, and applied to ⅜″ concave white placebos, as in Example 5, to obtain bright white film coatings.

[0038] Example 1 was repeated, except that the dispersion was sprayed onto 15000 grams of oyster shell substrates. This produced a bright white film coating on the oyster shell substrates.

[0039] Although it is preferred to make the coating dispersions of the invention from the inventive dry film coating compositions, the inventive coating dispersions may be made by adding the individual components of the inventive dry film coating composition to water to form the inventive coating dispersions.

[0040] Advantages

[0041] The invention provides a film coating that possesses good film adhesion and a smooth surface.

[0042] Moreover, the invention produces a bright white film coating that is noticeably brighter than white film coatings produced using HPMC-based coating compositions.