[Ketamine as antidepressant: the current study situation].

The treatment of depressive episodes is characterized by a delay in response of antidepressant medications and high rates of therapeutic failure. In recent years several open and five controlled trials have demonstrated the antidepressant efficacy of ketamine for major depression. In addition a recent study established the utility of nasal ketamine which may render the necessity of intravenous administration obsolete. The current state of evidence is reviewed and discussed.