Melvin D. Shelton

Current research on rapid cycling bipolar disorder and its treatment

Rapid cycling is a pattern of presentation of bipolar disorder that specifies the course of the illness and is associated with a greater morbidity. The validity of rapid cycling as a distinct course modifier for bipolar disorder has been demonstrated and the term has been incorporated into the DSM-IV. The phenomenon of rapid cycling tends to appear late in the course of the disorder, occurs more frequently among females, and is more frequently seen in patients with bipolar type II disorder. Stimulants such as cocaine may also play some role in rapid-cycling. It is generally accepted that a recent history of rapid cycling predicts non-response to monotherapy with lithium and probably carbamazepine as well; however it is also possible that concurrent use of antidepressants may play a role in destabilizing the illness course under these agents. Thus, clinical considerations suggest that discontinuing antidepressants may facilitate the recovery process. Among clinically available monotherapies, valproate and lamotrigine appear to be the most useful clinically. However, other treatments such as lithium, carbamazepine, the atypical antipsychotic agents, thyroid hormone, and bupropion are frequently needed augmentation strategies. Electroconvulsive therapy may also prove efficacious in selected cases. The present paper provides a critical review of the evidence for the foregoing clinical issues in rapid cycling.

A pilot study of topiramate as monotherapy in the treatment of acute mania.

This small-scale pilot study was performed to grossly document safety and any evidence of efficacy of topiramate in bipolar disorder. Ten patients hospitalized for acute mania were given open-label topiramate monotherapy for up to 28 days. The mean Young Mania Rating Scale (YMRS) score decreased from 32 (range, 26–40) at baseline to 22 (range, 2–40) at the end of the study. Five patients exhibited evidence of moderate to marked improvement, three subjects had at least a 50% reduction in YMRS scores, and the other two patients experienced an improvement of 25% to 49% on the YMRS. The preliminary findings of this small series suggest that topiramate may be effective in acute mania. Double-blind controlled trials are now needed to further investigate the efficacy and safety of topiramate in bipolar disorder.

Controlled trials in bipolar I depression: focus on switch rates and efficacy

Until recently, the rate at which patients switch from bipolar depression to the manic or hypomanic phase of the disorder during treatment with antidepressant medications was poorly defined. The completion of three large-scale, double-blind controlled trials in bipolar I depression has improved understanding of this phenomenon. The low switching rates observed in these studies of lamotrigine, paroxetine and moclobemide may indicate a special application of these drugs in the management of patients prone to antidepressant-induced switching. These studies also confirm prior suggestions that tricyclic antidepressants present the highest risk of switching. At present there is no consensus over the optimal definition of switching. Standardising the definition may lead to improvements in the clinical management of bipolar disorder.

Latest maintenance data on lamotrigine in bipolar disorder

Two 18-month, randomised, double-blind trials have compared lamotrigine, lithium, and placebo as maintenance treatment in a total of 1315 recently manic or depressed patients with bipolar I disorder. Individual and combined analyses of these studies showed that both lamotrigine and lithium significantly prolonged the time to intervention for any mood episode compared with placebo. Lamotrigine was primarily effective against depression and lithium was primarily effective against mania. There was no evidence that lamotrigine induced mania/hypomania/mixed states, caused episode acceleration, or destabilised the overall course of illness. Lamotrigine was well tolerated, with a placebo-like adverse-event profile. In summary, lamotrigine is an effective and well-tolerated maintenance treatment for bipolar I disorder, providing a spectrum of efficacy complementary to that of lithium.

Clinical Studies on the Use of Lamotrigine in Bipolar Disorder

New mood stabilizers that possess efficacy in the depressed phase of bipolar disorder are needed. The use of marketed antidepressants puts bipolar patients at some increased risk for drug-induced hypomania/mania and rapid cycling. During the development of the antiepileptic, lamotrigine, the drug was observed to improve mood, alertness, and social interactions in some patients with epilepsy. These early observations provided the rationale for investigations into lamotrigine’s potential efficacy in bipolar disorder. There are now 14 open clinical reports involving a total of 207 lamotrigine-treated patients with bipolar disorder that suggest this drug possesses a broad spectrum of efficacy in the management of the depressed, hypomanic, manic, and mixed phases of bipolar disorder. In an attempt to replicate and extend these preliminary open-label prospective findings, a series of multicenter, double-blind, placebo-controlled studies evaluating the efficacy and dose-response relationships of lamotrigine in the various phases of the illness, including both acute and maintenance designs in both bipolar I and II disorder, is ongoing.