S-ketamine for the treatment of depression

Ketamine infusion has been reported to rapidly relieve depressive symptoms and suicidal ideation in patients with treatment-resistant depression (TRD). It has also been tested in electroconvulsive therapy (ECT) anaesthesia and has been suggested to enhance the response to ECT. S-ketamine is less studied than a racemic mixture or R-enantiomer in these patients. S-ketamine is more potent as an anaesthetic and might thus also have a better antidepressive effect. In this article we present recent data concerning the antidepressive and adverse effects of S-ketamine compared with racemic and R-ketamine in major depressive disorder (MDD), especially in TRD. Based on recent literature, it is obvious that S-ketamine also possesses antidepressive properties. In ECT anaesthesia, S-ketamine might enhance the antidepressive effect of this treatment. S-ketamine may also be preferable when compared with other anaesthetics regarding adverse cognitive effects. Its adverse psychotomimetic effects may be avoidable when used in anaesthetic doses. Although the data on S-ketamine at the moment is only based on case reports and expert opinions rather than adequate prospective randomized studies, it still may offer an important option when treating severe and resistant depression.