In vitro and in vivo techniques to assess the performance of gastro-retentive drug delivery systems: a review

BACKGROUND: Interest in gastro-retentive drug delivery systems (GRDDS) can be attributed to the desire for increased patient convenience (once daily dosing) and to increase the therapeutic index (reduced C(max), increased C(min)). A range of evaluation techniques for GRDDS exist for in vitro and in vivo evaluation. OBJECTIVE: The aim of the present review is to describe the methodologies used for in vitro and in vivo evaluations of GRDDS. METHODS: The proposed critical parameters for floating and swelling types of GRDDS are discussed. Modifications in dissolution testing and improved biorelevant testing methods are also described. The in vivo techniques for measuring gastro-retentive performance are also summarised. CONCLUSION: The described methods can be used as assessment techniques for the evaluation and development of GRDDS. With these techniques, it is possible (with appropriate controls) to determine if a GRDDS provides hope for advantages of extended residence time in the stomach.