[(Es)ketamine: practice update]

Ketamine has been established as an anesthetic agent for decades. Around the turn of the millennium initial clinical studies demonstrated that subanesthetic doses of ketamine can exert antidepressant effects in treatment-resistant depression. These findings established the concept of an effective glutamatergic antidepressant treatment and initiated a paradigm shift. For many years, intravenous ketamine was used off-label in specialized centers; however, with the approval of intranasal esketamine, a standardized and reimbursable treatment option has now become available and the role of off-label intravenous ketamine infusion has consequently diminished in routine clinical practice. Esketamine is approved exclusively in combination with a selective serotonin reuptake inhibitor (SSRI) or a serotonin-norepinephrine reuptake inhibitor (SNRI) and requires administration in a specifically structured setting with defined monitoring. This article provides a practice-oriented update on the mechanism of action, indications, contraindications, the approved treatment regimen, safety requirements and the positioning within the therapeutic algorithm.