Gastric-soluble capsule film coatings are some polymer materials that can be dissolved in the stomach and are suitable for general tablet film coatings. There are four here.

    HPMC is one of the most commonly used film coating materials. PVP can also be used to make film coatings, which are easily soluble in water, ethanol, and gastrointestinal fluids, but are prone to sticking during coating, and tend to absorb moisture and soften after film formation. The rests are hydroxypropyl cellulose (HPC) and acrylic resin VI.

    HPMC can be divided into the instant type and hot-melt type. The instant type disperses rapidly in cold water, and the viscosity of the liquid gradually increases after about 2 minutes. The thermally soluble type forms agglomerates in cold water, dissolves and disperses in hot water, and the viscosity of the solution increases when it reaches room temperature. At present, the instant high viscosity 3 500~5 600 is widely used in the pharmaceutical industry, and it is a material with a better coating effect. , The coating film is very stable under heat, light, air, and certain humidity. For example, in order to solve the problem of moisture absorption of Biantong capsules, the traditional Chinese medicine granules of Biantong capsules were film-coated with HPMC, and the moisture absorption rate was used as the investigation index to study the factors affecting the moisture absorption rate of the coated particles during the coating process. Under the conditions of 75% humidity and 100% relative humidity, the moisture absorption rate of the coated granules is slower than that of the uncoated granules, and the critical relative humidity of the coated granules is higher than that of the uncoated granules. Therefore, the traditional Chinese medicine granules of Biantong Capsules are coated with HPMC film, which has a good effect on moisture resistance.