摘要：

A sustained-release pharmaceutical preparation comprising an admixture of uncoated and/or single walled coated drug, and multi-units of microparticles of a multi-walled coated drug. The microparticle structure preferably has a core drug, an inner wall microencapsular enteric coating, such as a polymethacrylic acid/acrylic acid copolymer or cellulose acetate phthalate, a solid acid such as citric acid, adipic acid, or an acidic ion exchange resin layered onto or included in the enteric layer, and an outer wall microencapsulated control coating, such as a polymethacrylic acid ester copolymer or ethyl cellulose. The multi-walled coated drug has a delayed, gradual, long-term release which takes place in the intestines while the uncoated and/or single walled coated drug has immediate therapeutic properties upon dissolution in the stomach. The enteric coating and control coating may be applied to core drug granules by a coacervation, spray coating or other process. The acid may be a separate layer applied by a spray coating or other process.

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