Abstract
The in-use stability of 25 drug products (oralliquids) with sensitive active ingredients was tested with a new test design simulating the stress of practical use. The results showed in so me cases a dramatic degradation of the active ingredient and the need of a reduced shelf life after first opening. Therefore the topic "in-use stability testing of human medicinal products" was brought forward to the QWP of the CPMPc by a member of the BlfA. Austria was appointed as rapporteur for the elaboration of the corresponding guideline.