Short-term fluoxetine monotherapy for bipolar type II or bipolar NOS major depression - low manic switch rate

Objectives: Current guidelines for the initial treatment of bipolar type II (BP II) major depressive episode (MDE) recommend using either a mood stabilizer alone or a combination of a mood stabilizer plus a selective serotonin re-uptake inhibitor (SSRI). This recommendation is the result of concern over antidepressant-induced manic switch episodes. However, recent evidence suggests that the manic switch rate may be low in BP II MDE during SSRI therapy. Methods: As part of a randomized, double-blind, placebo-controlled relapse-prevention study of fluoxetine monotherapy in BP II MDE, 37 patients received open-label fluoxetine 20 mg every day for up to 8 weeks. Outcome measures included the Hamilton Depression Rating (HAM-D 17) rating and the Young Mania Rating (YMR) scale. Results: Eleven of 23 patients (48%) who completed 8 weeks of fluoxetine treatment showed a HAM-D 17 reduction of greater than or equal to50%, while 14 (38%) of all treated patients had greater than or equal to50% reduction in baseline HAM-D 17 score. Using a conservative YMR score of greater than or equal to8 to identify hypomanic symptoms, the frequency of patients with YMR score greater than or equal to8 during fluoxetine did not differ from that seen during the screen and baseline period. Only three patients (7.3%) had symptoms suggestive of hypomania, and only one patient stopped treatment because of a rapid mood swing into depression. Limitations: Fluoxetine was given at a fixed dose of 20 mg everyday. Fluoxetine was prescribed in an open-label manner, and the sample size was limited. Conclusions: These observations support the findings of a low manic switch rate during SSRI monotherapy of BP II MDE, and suggest that fluoxetine monotherapy may be a safe and effective initial treatment of BP II MDE.