Adsorption of drugs onto a poly(acrylic acid) grafted cation-exchange membrane

The influence of pH, ionic strength and the concentration of albumin in the adsorption medium as well as the charge and lipophilicity of a model drug on their adsorption onto poly(acrylic acid) grafted poly(vinylidene fluorid e) (PAA-PVDF) membranes was evaluated. The PAA-PVDF membrane is a responsiv e porous polymer membrane that we have studied for controlled drug delivery . Sodium salicylate (anionic), flunitrazepam (neutral), primidone (neutral) , desipramine (cationic) and thioridazine (cationic) were used as model dru gs. The extent of drug adsorption was dependent on pH. Drug adsorption was enhanced by the dissociation of the grafted PAA chains and by a positive ch arge and a high lipophilicity of the drug. increasing the ionic strength of the medium retarded the adsorption of the cationic drugs. Interestingly, t he present results showing that drugs are adsorbed onto the membrane while albumin is not adsorbed onto the membrane suggest that the PAA-PVDF membran e may be suitable for separating drugs from proteinaceous substances for su bsequent monitoring and evaluation. (C) 1999 Elsevier Science B.V. All righ ts reserved.