Fluorescence recovery after photobleaching: a versatile tool for mobility and interaction measurements in pharmaceutical research.

This review introduces the basics of fluorescence recovery after photobleaching (FRAP) from a theoretical and an instrumentational approach. The most interesting and innovative applications with a pharmaceutical point of view are briefly discussed and possible future applications are suggested. These future applications include research on the mobility of macromolecular drugs in macro- or microscopic pharmaceutical dosage forms, mobility, and binding of antitumor drugs in tumor tissue, intracellular trafficking of gene complexes and mobility of drugs in membranes prior to transmembrane penetration. The paper is also intended to be an introductory guideline to those who would like to get involved in FRAP related experimental techniques. Therefore, comprehensive details on different setups and data analysis are given, as well as a brief outline of the problems that may be encountered when performing FRAP. Overall, this review shows the great potential of FRAP in pharmaceutical research. This is complemented by our own results illustrating the possibility of performing FRAP in microscopic dosage forms (microspheres) using a high resolution variant of FRAP.