A review of the evidence for the use of antipsychotics in the maintenance treatment of bipolar disorders.

Antipsychotic agents have long had a place in the clinical treatment of bipolar disorder, in both acute and maintenance phases. Recent clinical research conducted with the new generation of antipsychotic agents has contributed enormously to the data available on antipsychotic agents in bipolar disorder. Even now, however, the clinical trial data relates principally to the short-term treatment of acute mania. With the exception of recent data generated during the clinical trial programme for olanzapine, studies of maintenance treatment, conducted with antipsychotic agents, both established and newly-introduced, have generally been small and prone to methodological weakness. As a result, many important clinical questions, concerning the utility of antipsychotic agents in bipolar maintenance, can not be answered by reference to the data. Taken together, the findings of the clinical trials in bipolar maintenance, conducted with antipsychotic agents other than olanzapine, can be regarded only as tentative. As was conducted with olanzapine, larger, more rigorously designed studies are required to provide definitive evidence of efficacy in longer-term treatment. Due to the logistical complexity and expense of these sorts of study, it is likely that, for many antipsychotic agents with a potential role in long-term treatment in bipolar disorder, the definitive studies will never be undertaken.