Patent ID: 8409561

Claim:
A method of removing sodium from an animal subject comprising administering to an animal subject in need thereof an effective amount of a core-shell composition comprising a cation exchange core and a semi-permeable shell wherein the semi-permeable shell comprises a polymer containing at least one of a poly-11 trimethylammonioundecylmethacrylate polymer, or a 11-dimethyl-aminodecylmethacrylate/laurylmethacrylate copolymer, wherein said semi-permeable shell has a high permeability to sodium in the duodenum where the shell is in a hydrated state at neutral pH and has a reduced permeability to sodium in the cecum and colon where it is in a collapsed-impermeable state when the pH is 5 or 6, whereby as the core-shell composition passes from the duodenum to the cecum and colon its permeability to sodium decreases.