Patent ID: 7794750

Claim:
A controlled-release matrix composition in a solid dosage form, consisting essentially of: a pharmaceutically effective amount of an active agent, or a pharmaceutically acceptable salt or solvate thereof; an ionic non-gelling matrix polymer that is practically insoluble and unswellable at a first aqueous fluid pH and is soluble at a second aqueous fluid pH, wherein the ionic non-gelling matrix polymer is selected from the group consisting of cellulose acetate phthalate, cellulose acetate succinate, polyvinylacetate phthalate, cellulose acetate maleate, cellulose acetate trimellitate, cellulose acetate butyrate, cellulose acetate propionate, a methacrylic acid-methyl methacrylate co-polymer, a methacrylic acid-ethyl acrylate co-polymer, a methacrylic acid-methyl acrylate-methyl methacrylate, and a combination thereof; a pH modifier present in an amount to control the release of the active agent from the composition, wherein the pH modifier is a pharmaceutically acceptable organic acid, or an alkali metal or alkaline earth metal salt thereof; and a soluble, non-gelling pharmaceutically acceptable excipient; wherein the controlled-release matrix composition is substantially free of a gelling or swelling excipient and does not contain a functional coating or a lipophilic component.