methods of inhibiting the uptake of cationic biocides into medical devices such as contact lenses and implants are described . methods of stabilizing emulsions containing cationic biocides are also described . in particular , the present invention provides for the use of polymers acting as labile anionic polyelectrolytes to reversibly bind cationic biocides . the reversible binding can reduce the deleterious effects of cationic biocides while maintaining biocidal activity . preferred polymers include galactomannan and polyvinyl alcohol .