Temporal change of accumulated charge and diffusion of drug in tape for percutaneous absorption

To investigate possibility of the space charge measurement in the tape with a drug for percutaneous absorption and possibility of the control in space charge movement that might be corresponding to the drug movement by the external signal, the space charge was measured in the tape added a drug for percutaneous absorption. The positive space charge caused by addition a drug was accumulated in the sample and travels to the cathode under the DC voltage. The apparent mobility in an acrylic adhesive was faster with increasing the drug content as well as the result from the conduction current measurement. It was considered that the conductivity increased in an acrylic adhesive by the movement of the drug, bringing higher carrier density and/or higher mobility. The accumulated charge was also measured under the voltage. The accumulated charge in the sample with a diffusion time at short time after the voltage application was bigger than that without a diffusion time. From these results, it was suggested that there was a possibility that the electrical field would control the movement of a drug.