The efficacy of lamotrigine in rapid cycling and non-rapid cycling patients with bipolar disorder

Background: Patients with bipolar disorder (BD) who have rapid cycling features are often treatment refractory. Clear and conclusive evidence regarding effective treatments for this group is not available. Methods: Patients with diagnoses of refractory bipolar disorder who were currently experiencing manic, mixed, depressive, or hypomanic episodes were treated with lamotrigine as add-on therapy (60 patients) or monotherapy (15 patients). We compared the efficacy of lamotrigine in the 41 rapid cycling and 34 non-rapid cycling patients with BD. Results: Improvement from baseline to last visit was significant among both rapid cycling and non-rapid cycling patients for both depressive and manic symptomatology. For patients entering the study in a depressive episode, improvement in depressive symptomatology was equivalent in the two groups. Among patients entering the study in a manic, mixed, or hypomanic episode, those with rapid cycling improved less in manic symptomatology than did non-rapid cycling patients. Among rapid cycling patients with initial mild-to-moderate manic symptom severity, improvement was comparable to that in nonrapid cycling subjects; however, the subset of rapid cycling patients with severe initial manic symptomatology had little improvement in mania. Rapid cycling patients had earlier onset and more lifetime episodes of mania, depression, and mixed mania. Conclusions: Lamotrigine was generally effective and well tolerated in this group of previously non-responsive, rapid cycling bipolar patients.