Polymeric sorbents for bile acids. I: Comparison between cholestyramine and colestipol.

Isotherms for the sorption of bile acids at 20 degrees C, in tris(hydroxymethyl)aminomethane.HCl(tris) and KH2PO4-NaOH (phosphate) buffers (pH 7.4), indicate that the binding by cholestyramine and colestipol is mainly through ionic linkages, although hydrophobic interactions are also of importance. Cholestyramine has a higher sorption capacity for bile acids, in both buffers, than colestipol. The chloride form of cholestyramine has a higher capacity for cholate in tris buffer than the iodide form. Increased ionic strength of the medium leads to decreased amounts of sorption.