Electroporation and electrophoresis system and method for achieving molecular penetration into cells in vivo

The electroporation system and method combine pulses having different characteristics for delivering molecules to cells in vivo. The pulses include a high-intensity pulse for inducing electroporation and a low-intensity pulse to induce electrophoretic molecule movement within an interstitial space, molecule adherence to a cell membrane, and electrophoretic movement of the molecule through the permeabilized membrane. The use of a high-intensity and a low-intensity pulse achieves improved delivery; reduction of intensity and/or duration of pulses for inducing electroporation; and decreased muscle stimulation, tissue damage, and patient discomfort