Efficacy and safety of fluoxetine in treating bipolar II major depressive episode

As many as 45% of patients with major depressive episode also meet DSM-TV c riteria for bipolar II (BP II) disorder. Although some clinicians advocate using a mood stabilizer in treating BP II depression, antidepressant monoth erapy has been less well studied in this disorder. As part of a prospective , placebo-controlled, relapse-prevention study in 839 patients, the efficac y and safety of short- and long-term fluoxetine treatment in patients with BP II major depression compared with patients with unipolar (UP) major depr ession was retrospectively examined. Eighty-nine BP II patients (mean age, 41 +/- 11 years) were compared with 89 age- and gender-matched UP patients and with 661 unmatched UP patients (mean age, 39 +/- 11 years). All receive d short-term fluoxetine therapy at 20 mg daily for up to 12 weeks. Complete remission was defined as a final Hamilton Rating Scale for Depression scor e less than or equal to 7 by meek 9 that was then maintained for 3 addition al weeks. Remitted patients were then randomly assigned to receive double-b lind treatment with one of the following: (1) fluoxetine 20 mg daily for 52 weeks; (2) fluoxetine for 38 weeks, then placebo for 14 weeks; (3) fluoxet ine for 14 weeks, then placebo for 38 weeks; or (4) placebo for 52 weeks. A ntidepressant efficacy mas similar in BP and UP patients during short-term therapy. Discontinuation for lack of efficacy was lower in BP II (5%) than in UP (12%) patients (p = not significant [NS]), whereas dropouts for adver se events mere similar in BP II(11%) and UP (9%) patients. During longterm relapse-prevention therapy, relapse rates mere similar in BP II and UP pati ents (p = NS) During short-term fluoxetine therapy, three BP II (3.8%) vers us no matched UP (p = NS) and 0.3% unmatched UP (p = 0.01) patients had a " manic switch." During long-term fluoxetine therapy, one (2%) BP II and thre e (1%) unmatched UP patients (one taking placebo) had a manic switch (p = N S). In conclusion, fluoxetine may be a safe and effective antidepressant mo notherapy for the shortterm treatment of BP II depression with a relatively low manic switch rate. Fluoxetine may also be effective in relapse-prevent ion therapy in patients with BP II disorder.