Efficacy of atypical antipsychotics in mood disorders

Lithium and valproate are well recognized as mood-stabilizing medications. However, a significant number of patients with bipolar disorder do not respond to or cannot tolerate the side effects of these drugs. As a result, a search for safer and more effective mood stabilizers for the treatment of bipolar disorder is ongoing. Antipsychotic medications have long been used as adjunctive therapy in combination with mood-stabilizing medications. Although conventional neuroleptics (also known as typical antipsychotics) such as haloperidol or chlorpromazine are effective antimanic agents, they do not appear to have any efficacy in treating comorbid depressive symptoms. Furthermore, typical antipsychotics are associated with a number of well-known side effects, such as extrapyramidal symptoms and tardive dyskinesia. Mood-stabilizing effects have recently been reported for a number of newer "atypical" antipsychotics that have a broader spectrum of efficacy and better safety profiles than the typical antipsychotics. The results of several clinical trials suggest that atypical antipsychotics, including risperidone, olanzapine, ziprasidone, and quetiapine, are effective for the treatment of acute mania, and open-label studies suggest that atypical antipsychotics may have long-term mood-stabilizing effects.