Ion binding compositions

#Ion selective sorbents have been used in human therapy to correct disorders in electrolyte balance, in conditions such as hyperphosphatemia, hyperoxaluria, hypercalcemia, and hyperkalemia. Hyperphosphatemia occurs in patients with renal failure, whose kidneys no longer excrete enough phosphate ions to compensate exogenous phosphate uptake in the diet. This condition leads to high serum phosphate concentration and high calcium x phosphate product. Although the etiology is not fully demonstrated, high calcium x phosphate product has been held responsible for soft tissue calcification and cardiovascular disease. Cardiovascular disease is the cause of death in almost half of all dialysis patients.

#Aluminum, calcium, and, more recently, lanthanum salts have been prescribed to control phosphate ion absorption in the gastrointestinal (GI) tract and restore systemic phosphate levels back to normal. However these salts liberate soluble aluminum and calcium cations in the GI tract, which are then partially absorbed into the blood stream. Aluminum absorption can cause serious side effects such as aluminum bone disease and dementia; high calcium uptake leads to hypercalcemia and puts patients at risk for coronary calcification.

#Metal-free phosphate binders such as strong base ion-exchanger materials, Dowex and Cholestyramine resins, have been suggested for use as phosphate binders. However, their low capacity of binding requires high dosage that is not well tolerated by patients.

#FIG. 1 is a schematic representation of one embodiment of a core-shell composition.

#FIG. 2 depicts the solute binding profile as a function of time for some embodiments of the invention.

#The present invention provides core-shell polymeric compositions. Also, methods and kits for using these compositions are described herein.

#Core Shell Compositions

#One aspect of the invention is a core-shell composition comprising a core component and a shell component. In a preferred embodiment, the core-shell composition is a polymeric composition and the core component can preferentially bind one or more target solutes, e.g., in the gastrointestinal (GI) tract of an animal. The term “animal” and “animal subject” as used herein includes humans as well as other mammals.