Comparison of the antimanic efficacy of carbamazepine and lithium carbonate by double-blind controlled study

A multi-institutional study comparing the antimanic effect of carbamazepine (CBZ) and lithium carbonate (Li) was performed using a double-blind group comparison design in a series of 105 patients with bipolar disorders. CBZ and Li were given for four weeks using a fixed-flexible method at an equipotent dose ratio of 1:1, starting from an initial dosage of 400 mg with a maximum dosage of 1200 mg. The final global improvement rate, based on the number of cases showing moderate to marked amelioration of manic symptoms, was 62% in the CBZ group and 59% in the Li group, with no significant difference being found between the two groups. Incidence of cutaneous side-effects was significantly higher in the CBZ group. The mean daily dosage and serum level of CBZ in the fourth week were 674 +/- 239 mg and 7.3 +/- 2.4 micrograms/ml respectively; these were within the therapeutic range. The daily dose and serum level of Li, however, were 710 +/- 239 mg and 0.46 +/- 0.22 mEq/l, and the Li level seemed to be too low to compare its therapeutic effect with that of CBZ. Prior to the present study, approximately 80% of the patients in both groups had been receiving antipsychotic medication, equivalent to 8.0 mg of haloperidol on average, without favorable response. This medication was maintained unchanged during treatment. While the shortcomings of the present study limit the interpretation of the data, it may be suggested that the usefulness of CBZ as a drug for the treatment of manic states is comparable to that of Li.