Conducting polymers are versatile and robust materials that have recently become attractive as controlled drug delivery systems. Possessing ion exchangeable properties, they can serve as carriers for numerous biologically active species, showing particular applicability in neural tissue engineering and regional chemotherapy. In the pursuit of the design of the most effective controlled drug delivery system, we aimed to compare the performance of the conducting polymer-based matrix as a function of doping anion, using chloride, perchlorate and dodecyl sulfate, respectively, as the primary dopants. Due to their different ion radius and mobility, selected ions were found to provide substantial changes into polymer characteristics, having strong effects into the uptake and release of a model drug, naproxen sodium salt. PEDOT/ClO4 matrix, particularly, was found to possess superior properties providing highest mass of the formed polymer (103.45 +/- 10.09 mu g cm(-2)), charge storage capacity (44.9 mC cm(-2)) and ion exchange capacity (0.122 +/- 0.003 mu mol cm(-2)), leading also to the highest amounts of loaded (0.024 +/- 0.002 mu mol cm(-2)) and released (from 0.71 +/- 0.10 mu g cm(-2) to 1.61 +/- 0.59 mu g cm(-2)) drug. (C) 2018 Elsevier Ltd. All rights reserved.