Mechanical testing methods for drug-releasing vaginal rings.

Vaginal rings (VRs) are currently marketed for contraceptive or hormone regulation purposes, and investigationally, have been widely reported for delivery of antiretrovirals to reduce HIV transmission. To date, there is no national or international standard for the mechanical testing and minimum performance characteristics of any VR based products. Here, we describe a series of mechanical tests examining the durometer hardness, static and dynamic compression response, tensile properties and twist resistance of vaginal rings. The tests were conducted on currently marketed VRs and a number of the International Partnership for Microbicides' (IPM) investigational VR formulations. With wider application in the field, the tests described herein could form the basis for a more standardised approach to the mechanical testing of VRs.