Objective: The authors evaluated the efficacy and safety of quetiapine plus lithium or divalproex in the prevention of recurrent mood events in patients with stabilized bipolar I disorder.
Method: A total of 1,953 patients received open-label quetiapine (400-800 mg/day in flexible, divided doses) with either lithium or divalproex (target serum concentrations 0.5-1.2 meq/liter and 50-125 microg/ml, respectively) for up to 36 weeks. After at least 12 weeks of clinical stability, 628 patients were randomly assigned to double-blind treatment with quetiapine or placebo, in combination with lithium or divalproex, for up to 104 weeks. The primary efficacy measure was time to recurrence of any mood event (mania, depression, or a mixed episode).
Results: Fewer patients in the quetiapine group experienced a mood event compared with the placebo group (20.3% versus 52.1%). The hazard ratio for time to recurrence of a mood event was 0.32. Hazard ratios were similar for mania and depression events (0.30 and 0.33, respectively). Sedation, weight increase, and hypothyroidism occurred more frequently in the quetiapine group, as did discontinuations due to adverse events. The incidence and incidence density of a single emergent blood glucose value > or =126 mg/dl were higher in the quetiapine group (12.6% versus 5.4%; 18.44 versus 9.56 patients per 100 patient-years). Adverse events were generally consistent with the known tolerability profile of quetiapine.
Conclusions: In patients stabilized on quetiapine plus lithium or divalproex, continued treatment was associated with a significant risk reduction in the time to recurrence of any mood event compared with placebo and lithium or divalproex.