Investigating the feasibility of accelerated drug release testing for intravaginal rings Wirkstofffreisetzung beschleunigte Freisetzungstests Vaginale Ringe Diffusion Qualitätskontrolle accelerated drug release testing vaginal rings diffusion quality control Accelerated drug release tests are essential for quality control (QC) of long acting (non oral) controlled release formulations. Real time release experiments are usually required for product development to understand the mechanism of release and to establish a correlation with in vivo release. Ideally the accelerated test should maintain the biorelevant aspect of the in vitro method and the mechanism of release should not change under accelerated test conditions. At the same time adequate discriminatory ability is a prerequisite as the accelerated test should be able to discriminate between batches with respect to manufacturing variables that can impact on bioavailability. The objective of this thesis was to develop accelerated drug release tests for intravaginal rings (IVRs) and to gain a mechanistic understanding of the principles that facilitate in vitro drug release under accelerated test conditions. A detailed evaluation of the in vitro release characteristics of the formulations under real time test conditions was considered as a prerequisite for developing predictive accelerated tests. Two formulations were subject of this study in which the mechanism of release is primarily governed by drug diffusion. One formulation was the commercially available Nuvaring® a combined hormonal contraceptive IVR that releases etonogestrel and ethinylestradiol with a constant rate over a duration of 3 weeks. The second formulation was a prototype of an investigational IVR that is ...