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.