A Comparative Study between Lithium and Extended-release Carbamazepine in Acute Mania: A Double-blind Clinical Trial

Background: Recently, numerous large clinical trials have been performed to evaluate the effectiveness and tolerability of extended-release formulations of carbamazepine in bipolar disorder. Objective: In the current study, we compared lithium with a prolonged-release form of carbamazepine (Tegretol CR) to evaluate its efficiency and safety in a group of patients with a diagnosis of acute mania. Methods: Fifty patients with the diagnosis of acute mania were selected for a three-week, doubleblind study, and were randomly administered lithium carbonate or tegretol CR. The main outcome measured in the present evaluation was the Manic State Rating Scale (MSRS), which was scored at baseline and weekly intervals up to the third week. Moreover, insight and overall illness severity and improvement were assessed using the Schedule for Assessment of Insight (SAI), the Clinical Global Impressions-Global Improvement scale (CGI-I), and the Clinical Global Impressions Severity Scale (CGI-S), respectively. The statistical significance was defined with a p-value ≤0.05, and the treatment efficacy was analyzed by independent samples t-test and repeated measures analysis of variance (ANOVA). Results: Despite the fact that the mean total score of MSRS improved significantly with respect to both lithium carbonate and tegretol CR at the end of the third week, the between-group analysis showed a significant advantage of lithium, regarding both frequency and intensity of symptoms, at the end of the study. The mean total score of SAI, as well, showed significant improvement caused by both of them. Nevertheless, while the CGI-I demonstrated significant improvement in participants taking lithium and tegretol CR, the CGI-S showed significant progress only with lithium. Besides, Cohen’s effect size analysis showed a large improvement of MSRS by lithium and medium improvement by tegretol CR. Post-hoc power analysis showed an intermediate power of 0.42 on behalf of the current evaluation. Conclusion: While both lithium carbonate and tegretol CR were found to be valuable for the improvement of manic symptoms, management with lithium appears to be more helpful.