Commonly used water-insoluble carriers are divided into three types: (1) Cellulose. Commonly used ones, such as ethyl cellulose (EC), are soluble in organic solvents such as ethanol and acetone, with large drug loading, good stability, and resistance to aging. Used in sustained-release solid dispersions, usually prepared by solvent evaporation. (2) Lipids. Commonly used lipid materials such as cholesterol, carnauba wax and castor oil wax, etc., can be used to prepare sustained-release solid dispersions by melting. (3) Polyacrylic resins. As poorly soluble carrier materials, there are polyacrylic resins containing quaternary ammonium groups. Such polyacrylic acid resins swell in gastric juice, are insoluble in small intestinal juice, but are not absorbed, and are widely used in the preparation of sustained-release solid dispersions.
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