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 feat ures are often treatment refractory. Clear and conclusive evidence regardin g effective treatments for this group is not available, Methods: Patients with diagnoses of refractory bipolar disorder who were cu rrently experiencing manic, mixed depressive, ol hypomanic episodes were tr eated with lamotrigine as add-on therapy (60 patients) or monotherapy (15 p atients). We compared the efficacy of lamotrigine in the 41 rapid cycling a nd 34 non-rapid cycling patients with ED. Results: Improvement front baseline to last visit was significant among bot h rapid cycling and non-rapid cycling patients for both depressive and mani c 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 nonr apid cycling subjects; however, the subset of rapid cycling patients with s evere initial manic symptomatology had little improvement in mania. Rapid c ycling patients had earlier onset and more lifetime episodes of mania, depr ession, and mixed mania. Conclusions: Lamotrigine was generally effective and well tolerated in this group of previously non-responsive, rapid cycling bipolar patients. (C) 19 99 Society of Biological Psychiatry.