Objective: Quetiapine monotherapy shows efficacy in bipolar depression. The analyses in this multicenter, double-blind, randomized, fixed-dose, placebo-controlled study evaluated effects of quetiapine monotherapy on anxiety symptoms in bipolar depression.
Method: Of 542 outpatients randomly assigned to treatment, 539 with bipolar I (N = 358) or bipolar II (N = 181) disorder experiencing a major depressive episode (DSM-IV) received 8 weeks of quetiapine monotherapy (600 or 300 mg/day) or placebo between September 2002 and October 2003. Anxiety assessments included the Hamilton Rating Scale for Anxiety (HAM-A) and relevant items from the Montgomery-Asberg Depression Rating Scale (MADRS) and Hamilton Rating Scale for Depression (HAM-D). Analyses evaluated the pooled dose groups versus placebo.
Results: At week 8, quetiapine 600 and 300 mg/day each demonstrated significant improvements in HAM-A total score versus placebo (-10.8 and -9.9 vs. -6.7, p < .001). Quetiapine (pooled doses) significantly improved HAM-A total score from week 1. In bipolar I depression, quetiapine showed significant improvement in HAM-A total score versus placebo (-10.4 vs. -5.1, p < .001). In bipolar I depression, quetiapine also showed significant improvements versus placebo on the HAM-A anxious mood and tension items, HAM-A psychic and somatic subscales, MADRS inner tension item, and HAM-D psychic anxiety item (all p < .001), but not the HAM-D somatic anxiety item. In bipolar II depression, quetiapine reduced the HAM-A total score more than placebo, but the difference was not statistically significant (-9.8 vs. -9.0, p = .473). In bipolar II depression, quetiapine showed significant improvement versus placebo on the HAM-A anxious mood, MADRS inner tension, and HAM-D psychic anxiety items (all p < .01).
Conclusion: Quetiapine monotherapy shows efficacy in treating anxiety symptoms in bipolar I depression; however, the anxiolytic effects in bipolar II disorder require further investigation.