The electrically modulated transdermal migration of diclofenac sodium (DS), diclofenac potassium (DP), and diclofenac diethylammonium (DD) drugs from the hydrogels of sodium alginate (NaAlg), carbopol (CP), and blends of NaAlg with CP prepared in 2:1, 2:1.5, and 2:2 ratios was investigated. The release of DS, DP, and DD was investigated through excised rat skin to study the effects of viscosity, pH, and the ionic strength of the receptor medium under the influence of an electrical current in a switch-on and switch-off mode. A pulsatile pattern of transport was observed that depended on the presence or absence of an electrical current. Drug transport was dependent on the electrical current, the ionic nature of drugs, and the ionic strength of the diffusion medium. Drug transport followed the sequence DS > DP > DD. A decrease in viscosity and an increase in the pH of the hydrogel were observed when an electrical current was applied. CP was more responsive to an electrical stimulus, but the rate of transport was higher for NaAlg. Increasing the amount of CP in the blends increased the electrical responsiveness. The blend hydrogel with a high CP content showed the highest enhancement in drug transport, whereas the NaAlg hydrogel showed the least. (C) 2005 Wiley Periodicals, Inc.