Mood stabilization in the treatment of bipolar disorder: focus on quetiapine

The use of at least one mood-stabilizing agent is common clinical practice in the treatment of bipolar disorder, regardless of the treatment setting or disease phase. However, a consensus definition of 'mood stabilizer' remains to be established. A mood stabilizer has been operationally described as an agent that is useful in at least one phase of bipolar disorder while not worsening any other phase of the illness. More stringent definitions have been proposed, and it can be argued that a clinically effective mood stabilizer would have efficacy in a broad range of affective, psychotic, behavioral and cognitive domains in all phases of bipolar disorder and would be well tolerated across a range of doses for sustained periods. Clinically effective mood stabilizers should treat mania and depression, while preventing recurrence and improving quality of life. Effective treatment should not precipitate mania, depression, or rapid cycling, and should minimize the burden of treatment-emergent side effects. Data from clinical studies of quetiapine are reviewed in context with the literature discussing traditional and emerging mood stabilizers. Using a liberal definition, the evidence for quetiapine qualifies it as a bimodal mood stabilizer based on its demonstrated effectiveness in the treatment of bipolar mania and depression. Further data suggest that quetiapine has promise across all phases of bipolar disorder with the potential to meet even the most stringent definitions of a mood stabilizer.