Abstract: A delayed, sustained-release pharmaceutical preparation is provided in which a water-soluble drug core is surrounded by a hydratable diffusion barrier which delays drug release for about 2-10 hours. The hydratable diffusion barrier comprises a film-forming polymer such as an acrylic resin, esterified acrylic resin, or ethyl cellulose or mixtures thereof and an additive which controls the rate of hydration and permeability of the hydratable diffusion barrier selected from the group consisting of lubricants, anionic surfactants, plasticizers, inert water-soluble materials, and mixtures thereof. In the preferred sustained-release pharmaceutical preparation, the film-forming polymer is combined with the additive and coated onto core drug granules to produce a diffusion barrier surrounding the core drug and form microparticles when the drug core is the preferred diltiazem hydrochloride, different coating thicknesses of the diffusion barrier are used to provide a long delay component and a short delay component.

Abstract: A delayed, sustained-release pharmaceutical preparation is provided in which a water-soluble drug core is surrounded by a hydratable diffusion barrier which delays drug release for about 2-10 hours. The hydratable diffusion barrier comprises a film-forming polymer such as an acrylic resin or ethyl cellulose or mixtures thereof and an additive which controls the rate of hydration and permeability of the hydratable diffusion barrier selected from the group consisting of fully esterified acrylic resins containing quaternary amine side chains, lubricants, anionic surfactants, plasticizers, inert water-soluble materials, and mixtures thereof. In the preferred sustained-release pharmaceutical preparation, the film-forming polymer is combined with the additive and coated onto core drug granules to produce a diffusion barrier surrounding the core drug and form microparticles which may then be admixed with an immediate release drug.

Abstract: A delayed, sustained-release pharmaceutical preparation is provided in which a water-soluble drug core is surrounded by a hydratable diffusion barrier which delays drug release for about 2-10 hours. The hydratable diffusion barrier comprises a film-forming polymer such as an acrylic resin or ethyl cellulose and an additive which controls the rate of hydration and permeability of the hydratable diffusion barrier selected from the group consisting of fully esterified acrylic resins containing quaternary amine side chains, lubricants, anionic surfactants, plasticizers, inert water-soluble materials, and mixtures thereof. In the preferred sustained-release pharmaceutical preparation, the film-forming polymer is combined with the additive and coated onto core drug granules to produce a diffusion barrier surrounding the core drug and form microparticles which may then be admixed with an immediate release drug.

Abstract: A sustained-release pharmaceutical preparation comprising an admixture of uncoated and/or single walled water soluble drug, such as aspirin, and dual walled coated drug. The dual wall structure has an inner wall microencapsular control coating, such as ethyl cellulose, and an outer wall enteric coating such as cellulose acetate phthalate. The dual walled coated drug has a delayed, gradual, long-term release which takes place in the intestines while the uncoated and/or single walled drug has immediate therapeutic properties upon dissolution in the stomach. The outer wall enteric coating may be applied to microencapsulated core drug by a coacervation, spray coating or other process.

Abstract: 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 polymethyacrylic 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.

Abstract: A sustained-release pharmaceutical preparation utilizing a pH controlled diffusion membrane composed of a pH sensitive film-forming polymer. The film forming polymer may be an enteric polymer containing phthalic acid with one carboxyl group attached to the enteric polymer via an ester bond, and the second carboxyl group remaining a free acid so that the modified film forming polymer is hydrophobic at low pH and hydrophilic at higher pH. Hydrophobic stearyl side chains are attached to the enteric polymer which causes the pH controlled diffusion membrane to remain insoluble at high pH. Alternatively, the pH sensitive film forming polymer may be a polymer containing hydrophobic and free acid groups so that the modified film forming polymer is hydrophobic at low pH and hydrophilic but insoluble at high pH.