Spectrum of activity of lamotrigine in treatment-refractory bipolar disorder.

Objective: New mood stabilizers are needed that possess efficacy for all phases of bipolar disorder. This study was designed to provide preliminary evidence for the safety and efficacy of a new anticonvulsant, lamotrigine, in adult patients with bipolar disorder who had been inadequately responsive to or intolerant of prior pharmacotherapy.
Method: A 48-week, open-label, prospective trial was conducted in 75 patients with bipolar I or bipolar II disorder. Lamotrigine was used as adjunctive therapy (N = 60) or monotherapy (N = 15) in patients presenting in depressed, hypomanic, manic, or mixed states.
Results: Of the 40 depressed patients included in the efficacy analysis, 48% exhibited a marked response and 20% a moderate response as measured by reductions in 17-item Hamilton Depression Rating Scale scores. Of the 31 with a hypomanic, manic, or mixed state, 81% displayed a marked response and 3% a moderate response on the Mania Rating Scale. From baseline to endpoint, the depressed patients exhibited a 42% decrease in Hamilton depression scale scores, and the patients presenting with hypomania, mania, or a mixed state exhibited a 74% decrease in Mania Rating Scale scores. The most common drug-related adverse events were dizziness, tremor, somnolence, headache, nausea, and rash. Rash was the most common adverse event resulting in drug discontinuation (9% of patients); one patient developed a serious rash and required hospitalization.
Conclusions: These open-label data provide preliminary evidence that lamotrigine may be an effective treatment option for patients with refractory bipolar disorder; however, potential benefits must be weighed against potential side effects, including rash.