Purpose Bipolar disorder is a chronic and recurrent condition often associated with treatment resistance and suicidality. There is an unmet need for effective treatment in this group of patients. Ketamine has been demonstrated to have antidepressant and antisuicidal properties in unipolar depression. Most of the available studies concern unipolar depression. Here, we present the efficacy and safety of IV ketamine as an add-on treatment in patients with bipolar I and bipolar II depression. Patients and Methods Thirteen patients with treatment-resistant bipolar depression (TRBD) received eight IV infusions of 0.5 mg/kg ketamine twice a week over four weeks. This is an open-label naturalistic observational study. Ketamine is an add-on treatment. Depressive symptoms were measured with the Montgomery–Asberg Depression Rating Scale (MADRS), and manic symptoms were measured with the Young Mania Rating Scale (YMRS). Psychomimetic symptoms were assessed with the Clinician-Administered Dissociative States Scale (CADSS) and the Brief Psychiatric Rating Scale (BPRS). Results The rates of response and remission after the seventh infusion of ketamine were 61.5% and 46.2%, respectively. A significant antisuicidal effect was observed in responders at the 7th infusion. Suicidality was measured with item 10 on the MADRS scale. The average time to respond was between 21.1 and 23.2 days to remission. There was an increase in the CADSS scores during the treatment compared to baseline and follow-up, but no differences between responders and non-responders were observed. No affective switch was observed according to the YMRS scale scores. Ketamine treatment was associated with a transient increase in arterial blood pressure. No serious adverse events, however, were observed. Conclusion This report presents the preliminary results of IV ketamine effectiveness and safety in treatment-resistant bipolar depression. The findings suggest that it is a feasible, safe and well-tolerated treatment option in this group of patients. There is a definite need for more studies in this field.

Anhedonia constitutes one of the main symptoms of depressive episode. It correlates with suicidality and significantly effects the quality of patient's lives. Available treatments are not sufficient against this group of symptoms. Ketamine is a novel, rapid acting strategy for treatment resistant depression. Here we report the change in symptoms of anhedonia measured by Snaith-Hamilton Pleasure Scale as an effect of eight ketamine infusions as an add-on treatment in 42 patients with treatment resistant depression. We also determined the effect of this change on the severity of depressive symptoms measured by Inventory for Depression Symptomatology-Self Report 30-Item (IDS-SR 30). We have observed statistically significant decrease in the level of anhedonia during ketamine treatment. After adjusting for potential confounders we have found that significant reduction in Snaith-Hamilton Pleasure Scale (SHAPS) after each infusion and 1 week post treatment was observed only among patients who did not use benzodiazepines. The reduction in symptoms of anhedonia mediates the antidepressive effect of ketamine. The results need replication in a larger randomized placebo controlled trial.

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The current psychopharmacological treatment approaches for major depression focus on monoaminergic interventions, which are ineffective in a large proportion of patients. Globally, treatment-resistant bipolar depression (TRBD) affects up to 33% of depressive patients receiving treatment. Certain needs are still unmet and require new approaches. Many studies are in favor of treatments with ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, even in single use, whose effects emerge in minutes to hours post administration. However, little data are available on ketamine performance in TRBD patients with somatic comorbidities, including highly prevalent ones, i.e., cardiovascular disease (heart failure, hypertension, post-myocardial infarct, arrhythmias, etc.) diabetes, and obesity, and depression-associated comorbidities such as stroke, epilepsy, as well as in the elderly population. The literature shows that treatment with ketamine is efficacious and safe, and the majority of adverse drug reactions are mild and tend to mostly disappear within 30 min to 2 h of ketamine administration.

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