The European Community (EC) Committee for Veterinary Medicinal Products (CVMP) has recently adopted a guideline for in-use (open-bott le) stability testing1 .There is no equivalent document offering guidance in the European (i.e. the EC and EEA) human medicinal product sector. However several Committee for Proprietary Medicinal Products (CPMP)/CVMP and International Standards Organisation (ISO) guidelines have recently addressed the need and conditions for performing an in-use stability study as a part of the development process for new medicinal products and medical devices