Long term treatment of bipolar disorder.

Bipolar disorder is characterised by recurrent episodes of mania and depression. The major objective of long term treatment is to reduce the frequency of these episodes. Lithium is the most widely recommended drug for this purpose, having been shown in controlled clinical trials to be more effective than placebo in reducing the likelihood of relapse. Unfortunately, its effectiveness in clinical practice is less than that predicted from these trials. A major cause of relapse is noncompliance, largely due to intolerance to adverse effects such as perceived mental sluggishness, thirst, polyuria and weight gain. Regular monitoring of lithium plasma concentrations is required to ensure that the range of 0.5 to 0.9 mmol/L is not exceeded. Concentrations above this can lead to toxic symptoms, which if unchecked can cause brain damage and even death. The anticonvulsant drugs carbamazepine and valproic acid (sodium valproate) are potential alternatives to lithium. Patients who relapse frequently despite lithium may benefit from the addition of one of these agents, although formal clinical trial evidence of the efficacy of such combination treatment is lacking. Antipsychotics, administered as a depot formulation, can reduce the likelihood of relapse in patients with frequent manic episodes, especially if associated with poor compliance. Psychological treatment and patient education have been shown to improve outcome, and should be made more widely available to all patients with bipolar disorder.