Objective: The authors examined long-term effectiveness and study retention during open-label quetiapine treatment for rapid cycling bipolar disorder.
Methods: An open-label, nonrandomized trial was conducted in 41 patients with rapid-cycling bipolar disorder (type I=33, type II=7, NOS=1) who received flexibly dosed quetiapine monotherapy (n=19) or add-on therapy (n=22) for up to one year. Linear growth curves were calculated to assess longitudinal changes in depression and mania.
Results: Linear growth curves demonstrated highly significant reductions in manic (p<.0001) and depressive (p<.0001) symptoms. Effect sizes were large against manic symptoms (add-on therapy: Cohen's d=0.66; monotherapy: Cohen's d=0.75) but small-to-moderate against depression (monotherapy: d=0.29; add-on therapy: d=0.40). Most patients (68%) prematurely terminated the protocol (mean duration: 18.0+/-16.9 weeks, mean dose: 195.6+/-196.1 mg/day), most often because of the need for additional psychotropic treatments.
Limitations: The study protocol involved an open label design with no placebo or active comparator group. The sample size provided adequate statistical power to detect large but not medium or small within-group effects. Premature dropout during the first six months precluded inferences about longer-term treatment outcome.
Conclusions: These observational findings provisionally suggest some benefit with quetiapine for both manic and depressive symptoms in rapid cycling bipolar disorder, at dosages somewhat lower than previously described either for mania or bipolar depression. The relatively high dropout rate underscores the complexity of rapid cycling bipolar disorder and likely necessity for pharmacotherapy adjustments over time.