[A Practical aspects of managing treatment-resistant depression - with a focus on esketamine].

It is relatively common for patients suffering from major depressive disorder to experience no significant improvement in their depressive symptoms despite trying several antidepressants and/or other treatment methods. This phenomenon is referred to in the scientific literature and clinical jargon as "treatment-resistant depression" (TRD). In our review paper, we attempt to present various definitions of TRD and conceptually related categories (e.g., "therapy-refractory depression"; "difficult-to-treat depression") and to discuss the risk factors, differential diagnosis, and treatment options for TRD. Among the therapeutic options used in the treatment of TRD, we focus on the theoretical and practical aspects of the use of esketamine nasal spray, which has been available in Hungary for several years. The section discussing the practical aspects of esketamine use is based not only on the literature but also on the long-term experience gained by the staff of the esketamine treatment center at the Semmelweis University Department of Psychiatry and Psycho therapy with a large patient population. Keywords: treatment-resistant depression; major depressive disorder; antidepressant; esketamine; treatment.