in-vivo Transdermal Drug Diffusion Depth Profiling-A New Approach to Opto-Thermal Signal Analysis

To measure the percutaneous penetration of the externally applied chemicals into human skin is very important for understanding how drugs can be delivered through the skin. Opto-thermal transient emission radiometry, or OTTER, is a new approach to such measurements which has been demonstrated to be suitable for measuring diffusion coefficients and partition constants in-vivo and in-vitro. We present a novel technique for analyzing opto-thermal signals to yield depth profiles of externally applied substances diffusing through skin. The mathematical background of the new technique, together with penetration depth profiles of different solvents into in-vivo human skin are presented.