The research plan involves the evaluation of ultrasonic energy as a means of enhancing the delivery of drugs through the skin. The main goal of the Phase I research is to build an experimental apparatus to determine the appropriate frequencies and intensities of sound energy to best effect increases in skin permeability. A battery of studies aimed at determining optimum settings for these variables is planned. After completing these ranging studies, the influence of ultrasound on the delivery of compounds having different polarities and molecular sizes will be characterized. These studies should indicate where the technology might be used in future transdermal delivery systems. Media which might be used to construct transdermal systems which allow the ultrasound energy to be efficiently passed into the skin are also to be evaluated using the apparatus. Together, these systematic studies should reveal the full potential of sonophoresis of ultrasonically mediated delivery of drugs for therapeutic purposes.