[Ketamine--a new treatment option for therapy-resistant depression].

The anaesthetic ketamine has been demonstrated to have an antidepressive effect in several randomised controlled studies. Patients with a severe therapy-resistant depression showed response rates of up to 70 % after one single ketamine infusion. In contrast to all other antidepressant treatment options, this effect was already apparent at 24 hours post infusion. However, the antidepressant effect is limited and after two weeks the relapse rate is around 70 %. This review gives a summary of the clinical value of ketamine in the treatment of depression focussing on clinical trials and the therapeutic mechanism of action. © Georg Thieme Verlag KG Stuttgart · New York.