ABSTRACT
In the past decades in vitro assessments of dosage form performance were undertaken
almost exclusively through studies of drug release kinetics. In recent years however, we
have seen the introduction of a range of imaging techniques that allow the pharmaceutical
scientist to investigate drug release processes and to discern more clearly the dynamic
events that contribute to the underlying drug release mechanisms. This complex area of
pharmaceutical research is still in its infancy and few of these techniques are in
widespread use, but within this chapter we aim to provide the reader with a brief
introduction to illustrate the potential of some of these new approaches. There are new
microscopic and spectroscopic techniques that can provide, for example, (i) a topological
or three-dimensional (3D) internal characterization of dose form morphology, (ii) surface
and internal chemical imaging, (iii) observations of the behavior of the whole dosage form
or of individual components on a macro-, micro-, or nanoscale, and (vi) allow real-time
monitoring of product quality during the manufacturing process. It is beyond the scope of
this chapter to provide descriptions of all new methods that have been applied to
characterize medicinal products in this way (a non-exhaustive summary is provided in
Table 1), and for explanations of theory and instrumentation the reader is directed to more
specialized and authoritative reviews. This chapter will focus on the potential of a few
chosen techniques that are experiencing a growing kernel of pharmaceutical application,
and which the authors believe have a high potential for enhancing our future
understanding of the way dosage forms behave.