This invention relates to film-forming or film coating compositions for use in the film coating of pharmaceutical tablets and the like and, more particularly, to such compositions in the form of wet powder blends or wet powder, clear, film-forming compositions.
Signorino U.S. Pat. No. 3,981,984 discloses edible concentrated pigment suspension in which pigments are suspended in non-aqueous solvents. Such pigment suspensions are shipped, for example, to pharmaceutical manufacturers who mix them with polymer solutions to form coating suspensions used for coating tablets and the like. Each of the pigment suspensions, polymer solutions and coating suspensions formed therefrom are in a non-aqueous solvent.
Porter et al. U.S. Pat. No. 4,543,370 discloses a dry edible film coating composition for use in pharmaceuticals, confectionary and food which comprises a mixture including pigment particles, polymer particles, a polymer plasticizer such as polyethylene glycol 400 and, advantageously, a surfactant such as dioctyl sodium sulfosuccinate. According to the patentees, such a film coating composition responds to a long standing desire to provide a dry edible film coating composition which can be constituted with solvent by the customer, that eliminates the problem of shipping of pigment dispersions containing aqueous or non-aqueous solvents, and also makes shipping less expensive by eliminating the weight of the solvents. In U.S. Pat. No. 4,543,370 it is stated to be known in the prior art to mix a dry polymer powder with pigment particles and to grind the mixture to obtain a dry polymer-pigment mixture which is then ground into a fine powder mixture. However, as further stated in this patent, when this fine polymer-pigment mixture is stirred into water and dispersed, the polymer makes lumps and fish eyes because it agglomerates and the resultant dispersion is not uniform. When this polymer-pigment dispersion is used as a coating dispersion and is coated onto tablets and the like, unless the dispersion is left to solvate for a considerable period of time like overnight, the coating is lumpy and not uniform.
The dry coating compositions of U.S. Pat. No. 4,543,370 are stated to be useful within an hour of being made up and not to require an overnight waiting period as was required by prior art aqueous and non-aqueous systems.
Heinze U.S. Pat. No. 4,636,261 discloses dry mixtures of powdered edible pigment particles and a dispersing agent which prevents agglomeration and facilitates dispersion into solution. The dispersing agent may be the salt of an organic compound containing one to four carboxylic acid groups or a salt of phosphoric acid.
In the preparation of clear film coating compositions for coating aspirin tablets and the like, it has heretofore been the practice to dissolve or disperse a polymer such as hydroxypropylmethyl cellulose in water and then wait for a period of 18 hours or so before applying the resulting polymer solution or dispersion to tablets or the like. Such a waiting period has been deemed necessary in order to rid the solution or dispersion of fish eyes and allow water to penetrate into or hydrate the polymer gel particles (fish eyes) which form upon dissolving or dispersing the polymer in water. While pre-conditioned or surface-treated polymers are available, it is necessary to add a base material to such polymers in order to allow the polymers to become hydrated and dissolve or disperse in water.
There remains a need for further improvements in film coating compositions with regard to their ability to disperse color in the coating of tablets, capsules and the like and their usefulness for this purpose upon preparation or within a short time thereafter.