A 52-week, open-label continuation study of lamotrigine in the treatment of bipolar depression

Lamotrigine has demonstrated efficacy for the acute treatment of depression in bipolar I patients in a placebo-controlled, monotherapy study. We describe the results of a 52-week, open-label continuation of that trial.

Patients meeting DSM-IV criteria for bipolar I disorder with a current major depressive episode who completed a 7-week, double-blind study of bipolar depression were offered 1 year of open-label lamotrigine therapy (flexible doses of 100-500 mg/day) in a continuation study. To maintain the acute study blind, the first 3 weeks of the continuation study remained blinded while patients previously randomly assigned to placebo were titrated to a lamotrigine dose of 50 mg/day. Patients who had been randomly assigned to lamotrigine continued at their fixed doses. Beginning at week 4, all patients received open-label lamotrigine for up to 49 additional weeks. Concomitant psychotropic medications were permitted during the open-label phase. Effectiveness (Montgomery-Asberg Depression Rating Scale [MADRS], Clinical Global Impressions-Improvement scale) and safety assessments were administered at weeks 4, 12, 24, 36, and 52. The study was conducted from June 1996 to December 1998.

Of 135 patients completing the acute study, 124 (92%) entered the continuation study: 77 had received lamotrigine and 47 had received placebo in the acute study. The mean duration of lamotrigine exposure was 10.4 months, with a mean modal dose of 187 mg/day. Sixty-nine patients (56%) completed 1 year of treatment. Significant and sustained improvement from baseline was seen in mean observed MADRS scores (p <.05). The proportion of patients achieving remission (MADRS score < or = 11) by week 4 of the study was 81.4%, and episodes of mania/hypomania occurred less frequently than in the preceding year. Headache was the most common drug-related adverse event.

During 1 year of open-label therapy with lamotrigine as adjunctive therapy or monotherapy, bipolar I patients experienced sustained improvement in depressive symptoms without evidence of mood destabilization.