New anticonvulsant medication uses in bipolar disorder

Therapy of bipolar disorders is a rapidly evolving field. Lithium has efficacy in classic bipolar disorders whereas divalproex sodium and carbamazepine may have broader spectrum efficacy that includes non-classic bipolar disorder. In the last 10 years, a series of anticonvulsants have been approved for marketing in the United States. Gabapentin has indirect g-aminobuytric acid-ergic actions, is generally well tolerated, and appears to have anxiolytic, analgesic, and hypnotic effects. Lamotrigine has antiglutamatergic actions and is generally well tolerated (aside from rash in 1 in 10, and serious rash in 1 in 1,000 patients). Lamotrigine is indicated for maintenance treatment in bipolar disorder. Emerging evidence suggests lamotrigine may have utility in bipolar disorder patients with depression and treatment-refractory rapid cycling, as well as analgesic effects. Topiramate and zonisamide may allow both weight loss, while topiramate may have specific efficacy in bulimia, binge eating disorder, and alcohol dependence. Two small studies found oxcarbazepine had similar efficacy to lithium and haloperidol in acute mania. Phenytoin, an older anticonvulsant, may have adjunctive acute mania efficacy. Levetiracetam, a newer anticonvulsant, may be worth exploring and has minimal drug-drug interactions. None of these newer agents has been shown effective in a large placebo controlled trial for acute mania. Although the clinical profiles of these newer anticonvulsants do not appear to overlap markedly with divalproex and carbamazepine (except perhaps for oxcarbazepine), these novel agents may still offer important new options in relieving a variety of specific target symptoms in patients with bipolar disorder.