The transfer of some catamphiphilic drugs across a water-solvent polymeric membrane interface is researched using differential voltammetric techniques with a solvent polymeric membrane ion-sensor and a four-electrode potentiostat. The standard ion transfer potentials of the antiarrhythmic drugs procainamide and quinidine, the antimalarial quinine and the anesthetics bupivacaine, lidocaine, procaine and tetracaine have been determined. In addition to their main pharmacological action, these drugs are of interest as multidrug resistance reversers in the chemotherapy treatment for cancer. The relationship between the pharmacological potency of the different drugs and the corresponding standard ion transfer potentials obtained in the present work has been studied. The relationship between the sensitivity of an amperometric sensor based on the ion transfer across the water-solvent polymeric membrane interface towards the different catamphiphilic drugs and the standard ion transfer potentials has also been studied. A dependence between them was obtained when the applied potential of the sensor was set at a value previous to the diffusion controlled zone. (c) 2007 Elsevier B.V. All rights reserved.