Treatment-emergent mania/hypomania during antidepressant monotherapy in patients with rapid cycling bipolar disorder

Objective: To study treatment-emergent mania/hypomania (TEM) associated with second-generation antidepressant monotherapy in patients with rapid cycling bipolar disorder (RCBD). Methods: Data of patients with RCBD (n=180) enrolled into two clinical trials were used to study the risk for TEM during second-generation antidepressant monotherapy. History of TEM was retrospectively determined at the initial assessment by asking patients whether they were exposed to second-generation antidepressants and if a hypomania/ mania episode emerged during the first fourweeks of treatment. Data were analyzed using t-test, chi-square, and logistic regression. Results: Ofthe 180 patients (bipolar I disorder, n = 128; bipolar II disorder, n = 52) with RCBD, 85% (n = 153) had at least one antidepressant treatment. Among these patients, 94.1% (144/153) had at least one antidepressant monotherapy treatment. Overall, 49.3% of patients had at least one TEM and 29.1% (116/399) of treatment trials were associated with TEM. In regression analysis, an inverse association between the number of mood episodes in the last 12 months and TEM was observed with an odds ratio of 0.9. However, gender, bipolar subtype, a lifetime history of comorbid anxiety disorder, substance use disorder, or psychosis, and age of mood disorder onset were not associated with TEM. For individual antidepressants, the rates of TEM varied from 42.1% for fluoxetine to 0% for fluvoxamine and mirtazapine. As a group, there was no difference between selective serotonin reuptake inhibitors and venlafaxine or bupropion in the incidence of TEM. Conclusions: Use of second-generation antidepressants as monotherapy in RCBD is accompanied by clinically relevant rates of TEM. Even in patients with RCBD, differential vulnerabilities to antidepressant TEM may exist.