A blinded, randomized comparison of immediate-release and extended-release carbamazepine capsules in manic and depressed bipolar subjects.

BACKGROUND

The anticonvulsant carbamazepine is approved by the FDA for treatment of acute mania. It is available in 2 formulations: immediate-release (IR) and extended-release carbamazepine capsules (ERCC). The relative efficacy of these formulations in acutely ill bipolar patients has not been previously investigated.

METHODS

This study is a subanalysis of a 3-month, blinded, equal, random-assignment comparison of adverse effect load of an IR carbamazepine formulation (Tegretol) and ERCC (Equetro) in type I or type II bipolar patients already receiving carbamazepine or clinically determined to benefit from carbamazepine treatment. Dosages were titrated to patients' clinical needs. Subjects who scored >15 on the Montgomery Asberg Depression Rating Scale (MADRS) or >14 on the Young Mania Rating Scale (YMRS) were included in this analysis. The primary outcome measures were the relative mood scores at the end of the study.

RESULTS

At the end of 3 months of treatment, all patients improved compared with their baseline, but there was no difference in mood ratings in subjects with an initial MADRS >15 (ERCC, 18.2 +/- SD 11.9, vs IR, 12.0 +/- 4.5; P = .3) or YMRS >15 (ERCC, 6.5 +/- 6.4, vs IR, 4.7 +/- 3.1; P = .7). When compared with their baseline, patients receiving IR improved earlier than patients receiving ERCC. There were no differences in overall adverse events in patients receiving IR or ERCC (23.1 +/- 13.42 vs 22.3 +/- 13.40; P = .9).

CONCLUSIONS

Carbamazepine is effective in treating symptoms of both mania and depression, and there are no significant differences in the relative efficacy of the IR or ERCC formulations.