The rapid cycling variant of bipolar disorder is defined as the occurrence of four periods of either manic or depressive illness within 12 months. Patients suffering from this variant of bipolar disorder have an unmet need for effective treatment. This review examines two major studies in an attempt to update understanding of the current therapies available to treat rapid cycling patients. The first trial compares lamotrigine versus placebo in 182 patients studied for 6 months. The second is a recently completed, 20-month trial comparing divalproate and lithium in 60 patients. Both trials had a double-blind, randomized parallel-group design. The data from the latter study indicate that there are no large differences in efficacy between lithium and divalproate in the long-term treatment of rapid cycling bipolar disorder. In addition, lamotrigine has the potential to complement the spectrum of lithium and divalproate through its greater efficacy for depressive symptoms.

There are few controlled studies evaluating the treatment of bipolar mixed states. Evidence suggests that mixed states may be more responsive to some anticonvulsants than to lithium. Olanzapine alone or in combination with divalproate or lithium has been adequately evaluated in randomized clinical trials involving mixed-state patients, whereas risperidone and quetiapine have not. There is also some evidence demonstrating the efficacy of ziprasidone and aripiprazole. The risk of switching to depression is high in mixed states. Conventional antipsychotics, such as haloperidol, may be less efficacious at protecting against a switch to depression than atypical antipsychotics, divalproate or lithium. When choosing drugs for the treatment of mania, and especially for the treatment of mixed states, their efficacy against manic and depressive symptoms, and their safety in terms of the risk of switching to depression should be taken into account.

Clinical guidelines for treatment and research of bipolar disorder greatly benefit from the synthesis of data from individual studies. The British Association for Psychopharmacology bases its guidelines on evidence from opinions (level D) to systematic reviews of primary trial data (level A). The report details conclusions of its 1-day consensus meeting to develop guidelines covering diagnosis, clinical management, pharmacotherapy for acute episodes, relapse prevention and treatment discontinuation. Monotherapy for long-term management is preferred, having reduced side-effects and drug interactions and improved compliance. Combination therapy is often preferred for acute episodes, using antipsychotics for mania or antidepressants for depression. Increased efficacy may be attributed to multiple mechanisms of action and potentially lower doses. In clinical practice, maintenance monotherapy has limited success for chronic episodes and polypharmacy is frequently used, though the best combination remains unclear. A new collaborative approach based on simple clinical trials is required to change current medical practice.