The selection of a suitable pressure sensitive adhesive represents an important step in the design of a transdermal drug delivery system (TDDS). In this study the percutaneous absorption of drugs during the application of adhesive TDDSs was investigated. Diffusion processes within the adhesive of a TDDS could be observed with a newly developed method based on confocal Raman microscopy. With the knowledge gained in these studies a new concept for the development of a TDDS was established. Finally this concept was tested successfully with two different drugs.
