Long-term outcome of bipolar depressed patients receiving lamotrigine as add-on to lithium with the possibility of the addition of paroxetine in nonresponders: a randomized, placebo-controlled trial with a novel design

Objective: In two previous manuscripts, we described the efficacy of lamotrigine versus placebo as add-on to lithium (followed by the addition of paroxetine in nonresponders) in the short-term treatment of bipolar depression. In this paper we describe the long-term (68 weeks) outcome of that study. Methods: A total of 124 bipolar depressed patients receiving lithium were randomized to addition of lamotrigine or placebo. After eight weeks, paroxetine was added to nonresponders for another eight weeks. Responders continued medication and were followed for up to 68 weeks or until a relapse or recurrence of a depressive or manic episode. Results: After eight weeks, the addition of lamotrigine to lithium was significantly more efficacious than addition of placebo, while after addition of paroxetine in nonresponders both groups further improved with no significant difference between groups at week 16. During follow-up the efficacy of lamotrigine was maintained: time to relapse or recurrence was longer for the lamotrigine group [median time 10.0 months (confidence interval: 1.1-18.8)] versus the placebo group [3.5 months (confidence interval: 0.7-7.0)]. Conclusion: In patients with bipolar depression, despite continued use of lithium, addition of lamotrigine revealed a continued benefit compared to placebo throughout the entire study.