Long-term treatment of bipolar disorder:how should we use lithium salts?

Despite the great quantity of evidence supporting the efficacy of lithium in the maintenance treatment of bipolar disorder (BD), its use has often been limited because of issues about the management of this compound. We aimed to evaluate the use of lithium in common clinical practice and to identify possible relationships between the trend over time of serum lithium levels and clinical course of the illness. Methods. 98 patients with bipolar I and bipolar II disorder (DSM-IV-TR) on maintenance treatment with lithium salts were recruited and followed up in a naturalistic trial at the Day Hospital of Psychiatric Clinic of Pisa. Diagnosis was confirmed using a structured interview, the SCID-I. During symptom assessment, the Clinical Global Impression-Bipolar Version Scale (CGI-BP) was used. Results. The sample is made up mainly of BI patients (87.8%) and lithium is used in association with anticonvulsants in 63%. Less than half of the sample (48%) presents average serum lithium levels in the therapeutic range (0.5-0.8 mEq/L); serum values of lithium within the range were seen more frequently in patients with manic/mixed episode, with manic/mixed polarity of onset, with a greater number of previous episodes, with a higher percentage of rapid cycling and in subjects treated with lithium associated with anticonvulsants. During the follow-up patients with average serum lithium levels within the therapeutic range obtained a clinical improvement in a significantly greater proportion compared to patients with average serum lithium levels lower than 0.50 mEq/L. Discussion. In clinical practice, lithium is often used at doses determining serum levels at the lower limits of the therapeutic range. Preliminary data on the prospective course of the illness support the importance of maintaining serum values of lithium within the therapeutic range.