Patients with chronic adrenal insufficiency need to adapt their glucocorticoid replacement dose in conditions of physical or psychological stress to prevent life threatening adrenal crisis. In cases of more severe impairment or unsecure gastrointestinal absorption (e.g. gastroenteritis, severe infectious disease), rapid and highly dosed administration of glucocorticoids is crucial. The study is conducted to offer female patients the possibility to perform efficient prednisone self-administration in emergency situations in a way of administration, which is easy to perform and accepted by the patients. Therefore, pharmacokinetics and safety of vaginal prednisone administration will be studied and compared to rectal administration.