The binding of cationic chlorpheniramine maleate (CPM) to the anionic water-soluble polymers (WSPs) alginic acid, carboxymethylcellulose, kappa-carageenan, and iota-carageenan was evaluated by diafiltration at pH 7.5 and in the absence and presence of 0.13M NaCl. CPM interacted with all of the WSPs when no NaCl was present in the solution, with charge-related formation constants of around 700 M-1 for all of the polymers, whereas the interactions were cleaved in the presence of 0.13M NaCl, indicating interactions of an electrostatic nature screened by the single electrolyte. (c) 2005 Wiley Periodicals, Inc.