Susan E. Kimmel

SPECTRUM OF EFFICACY OF VALPROATE IN 78 RAPID-CYCLING BIPOLAR PATIENTS

&NA; The rapid‐cycling variant of bipolar disorder constitutes about 15%‐20% of all bipolar patients, and 72%‐82% of these patients exhibit less than adequate response to lithium therapy. Valproates spec‐ trum of efficacy was examined in 78 patients with rapid‐cycling bipolar disorder in a prospective, open, 15.8‐month trial. Thirty patients received valproate monotherapy and 48 received combination therapy. Treatment assignment was nonrandomized and based on prior treatment history. A marked acute response was seen in 54% of the patients with mania, 87% of those with mixed states, and 19% of those with depression. Marked prophylactic responses were seen in 72% of manic patients, 94% of mixed states patients, and 33% of depressed patients. In addition, moderate acute antimanic responses were observed in another 31% of the patients, prophylactic antimanic responses in 17%, acute antimixed state responses in 0%, prophylactic antimixed state responses in 0%, acute antidepressant responses in 25%, and prophylactic antidepressant responses in mixed states in 34%. Pattern analysis was conducted to examine the spectrum of efficacy of valproate in various cells (e.g., the cohort of patients who had an acute antimanic response to the drug). Pattern analysis showed that 40% of the patients with a marked prophylactic antimanic response had a marked antidepressant response to valproate. However, among the patients with a marked antidepressant response to valproate, 91% had a marked antimanic response. The most common side effects of valproate in our study, as in earlier studies, were gastrointestinal problems (nausea, stomach cramps, diarrhea), tremors, lethargy, and hair thinning. Life charting techniques disclosed a bimodal distribution of episode frequencies, with the first mean approximating 10 episodes per year and the second estimated at 30 per year or too numerous to count. Consistent with previous observations, our data suggest that valproate has marked antimanic efficacy, minimal to moderate antidepressant properties, and marked antimixed state efficacy.

Predictors of valproate response in bipolar rapid cycling

Multiple regression/discriminant analyses were separately conducted to generate predictors of acute and prophylactic antimanic and depressive outcome in 101 valproate-treated bipolar rapid cyclers. Predictors of good antimanic response included decreasing or stable episode frequencies and nonpsychotic mania. Predictors of good antidepressant response included nonpsychotic mania worsening over the years of the illness and absence of borderline personality disorder comorbidity. This report confirms prior findings that indicate that valproate possesses marked acute and prophylactic antimanic and antimixed effects with only poor to moderate antidepressant properties.

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.

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.

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.