Symptom modulation and tolerability of intravenous ketamine in treatment-resistant bipolar depression: A retrospective study

Ketamine's use in treating bipolar depression must account for risks, such as switching to manic episodes or worsening symptoms. This study examines ketamine's impact on depressive symptoms, focusing on ‘inner tension,’ ‘sleep reduction,’ and ‘suicidal ideation’ over four weeks in treatment-resistant bipolar disorder (TR-BD) patients. Fifty-nine patients with TR-BD were treated consecutively with ketamine (avg dose 0.8 mg/kg). Results showed significant reductions in MADRS scores without manic switches. Ketamine was well-tolerated despite polypharmacy. Antidepressant treatment of bipolar depression requires great caution because of the risk of switching to manic-mixed episodes and worsening of symptoms such as internal tension, psychomotor agitation, and suicide risk. The aim of this study was to evaluate the efficiency and tolerability of intravenous ketamine in patients with bipolar I or bipolar II disorder and a current treatment-resistant depressive episode (TR-BD), with the aim of examining: 1) the risk of manic switches; 2) the effect on global depressive symptoms as measured by the Montgomery-Åsberg Depression Rating Scale (MADRS); and 3) the specific effects on the MADRS items of internal tension, sleep disturbance, and suicidal ideation over a four-week period. Fiftynine patients with TR-BD (51.4 ± 12.3 years; 30 % female) treated consecutively with intravenous ketamine (mean dose 0.8 mg/kg) were included in this study. No ketamine-treated patient experienced a manic switch during the observation period. A statistically significant decrease (i.e., improvement) in MADRS global score and scores on the Internal Tension, Reduced Sleep, and Suicidal Ideation items was observed from the second week, with no evidence of worsening of the above symptoms. Patient-reported adverse events were generally mild to moderate.