Emerging trends in the treatment of rapid cycling bipolar disorder: a selected review

A pilot pharmacogenetic study of calcium channel blocker treatment of bipolar mania

Common genetic variants located in calcium channel genes are important markers of genetic susceptibility for bipolar disorder (BD). Previous clinical trials with Calcium Channel Blocker (CCB) medication improved mood stability for some BD patients. We hypothesize that manic patients who carried calcium channel risk variants would differentially benefit from treatment with CCBs. In this pilot study, 50 BD patients (Chinese: 39; US: 11) who were hospitalized for manic episodes were given add-on CCB treatment. We determined genotypes for each patient. There was a significant decrease in the Young Mania Rating Scale (YMRS) after add-on medication treatment. Of note, two intronic variants of the Calcium Voltage-Gated Channel Subunit Alpha1 B (CACNA1B) were associated with treatment outcomes for manic patients: rs2739258 and rs2739260. BD rs2739258/rs2739260 AG-allele carriers had a better treatment response with add-on CCB than those carrying the AA or GG genotypes by survival analysis. Although these findings did not pass multiple testing correction, this study suggests that single-nucleotide polymorphisms (SNPs) residing in calcium channel genes could be predictors for response to add-on CCB treatment of bipolar mania patients, and that calcium channel genes may be involved in treatment responses for BD.

Calcium Channel Antagonists for Mood Disorders

PURPOSE

Development of new thymoleptic medications has primarily centered on anticonvulsants and antipsychotic drugs. Based on our studies of intracellular calcium ion signaling in mood disorders, we were interested in the use of novel medications that act on this mechanism of neuronal activation as potential mood stabilizers.

METHOD

We reviewed the dynamics of the calcium second messenger system and the international body of data demonstrating increased baseline and stimulated intracellular calcium levels in peripheral cells of patients with bipolar mood disorders. We then examined studies of the effect of established mood stabilizers on intracellular calcium ion levels and on mechanisms of mobilization of this second messenger. After summarizing studies of calcium channel blocking agents, whose primary action is to attenuate hyperactive intracellular calcium signaling, we considered clinical experience with this class of medications and the potential for further research.

FINDINGS

Established mood stabilizers normalize increased intracellular calcium ion levels in bipolar disorder patients. Most case series and controlled studies suggest an antimanic and possibly mood stabilizing effect of the calcium channel blocking medications verapamil and nimodipine, with fewer data on isradipine. A relatively low risk of teratogenicity and lack of cognitive adverse effects or weight gain suggest possible applications in pregnancy and in patients for whom these are considerations.

IMPLICATIONS

Medications that antagonize hyperactive intracellular signaling warrant more interest than they have received in psychiatry. Further experience will clarify the applications of these medications alone and in combination with more established mood stabilizers.

Applications of calcium channel blockers in psychiatry: pharmacokinetic and pharmacodynamic aspects of treatment of bipolar disorder

Introduction: Calcium channel blockers (CCBs) comprise a heterogeneous group of medications that reduce calcium influx and attenuate cellular hyperactivity. Evidence of hyperactive intracellular calcium ion signaling in multiple peripheral cells of patients with bipolar disorder, calcium antagonist actions of established mood stabilizers, and a relative dearth of treatments have prompted research into potential uses of CCBs for this common and disabling condition. Areas covered: This review provides a comprehensive overview of intracellular calcium signaling in bipolar disorder, structure and function of calcium channels, pharmacology of CCBs, evidence of efficacy of CCBs in bipolar disorder, clinical applications, and directions for future research. Expert opinion: Despite mixed evidence of efficacy, CCBs are a promising novel approach to a demonstrated cellular abnormality in both poles of bipolar disorder. Potential advantages include low potential for sedation and weight gain, and possible usefulness for pregnant and neurologically impaired patients. Further research should focus on markers of a preferential response, studies in specific bipolar subtypes, development of CCBs acting preferentially in the central nervous system and on calcium channels that are primarily involved in neuronal signaling and plasticity.

Pharmacology of L-type Calcium Channels: Novel Drugs for Old Targets?

Inhibition of voltage-gated L-type calcium channels by organic calcium channel blockers is a well-established pharmacodynamic concept for the treatment of hypertension and cardiac ischemia. Since decades these antihypertensives (such as the dihydropyridines amlodipine, felodipine or nifedipine) belong to the most widely prescribed drugs 
world-wide. Their tolerability is excellent because at therapeutic doses their pharmacological effects in humans are limited to the cardiovascular system. During the last years substantial progress has been made to reveal the physiological role of different L-type calcium channel isoforms in many other tissues, including the brain, endocrine and sensory cells. 
Moreover, there is accumulating evidence about their involvement in various human diseases, such as Parkinson's disease, neuropsychiatric disorders and hyperaldosteronism. In this review we discuss the pathogenetic role of L-type calcium channels, potential new indications for existing or isoform-selective compounds and strategies to minimize potential side effects.

The Physiology, Pathology, and Pharmacology of Voltage-Gated Calcium Channels and Their Future Therapeutic Potential

Voltage-gated calcium channels are required for many key functions in the body. In this review, the different subtypes of voltage-gated calcium channels are described and their physiologic roles and pharmacology are outlined. We describe the current uses of drugs interacting with the different calcium channel subtypes and subunits, as well as specific areas in which there is strong potential for future drug development. Current therapeutic agents include drugs targeting L-type Ca(V)1.2 calcium channels, particularly 1,4-dihydropyridines, which are widely used in the treatment of hypertension. T-type (Ca(V)3) channels are a target of ethosuximide, widely used in absence epilepsy. The auxiliary subunit α2δ-1 is the therapeutic target of the gabapentinoid drugs, which are of value in certain epilepsies and chronic neuropathic pain. The limited use of intrathecal ziconotide, a peptide blocker of N-type (Ca(V)2.2) calcium channels, as a treatment of intractable pain, gives an indication that these channels represent excellent drug targets for various pain conditions. We describe how selectivity for different subtypes of calcium channels (e.g., Ca(V)1.2 and Ca(V)1.3 L-type channels) may be achieved in the future by exploiting differences between channel isoforms in terms of sequence and biophysical properties, variation in splicing in different target tissues, and differences in the properties of the target tissues themselves in terms of membrane potential or firing frequency. Thus, use-dependent blockers of the different isoforms could selectively block calcium channels in particular pathologies, such as nociceptive neurons in pain states or in epileptic brain circuits. Of important future potential are selective Ca(V)1.3 blockers for neuropsychiatric diseases, neuroprotection in Parkinson's disease, and resistant hypertension. In addition, selective or nonselective T-type channel blockers are considered potential therapeutic targets in epilepsy, pain, obesity, sleep, and anxiety. Use-dependent N-type calcium channel blockers are likely to be of therapeutic use in chronic pain conditions. Thus, more selective calcium channel blockers hold promise for therapeutic intervention.

L-type calcium channels as drug targets in CNS disorders

L-type calcium channels are present in most electrically excitable cells and are needed for proper brain, muscle, endocrine and sensory function. There is accumulating evidence for their involvement in brain diseases such as Parkinson disease, febrile seizures and neuropsychiatric disorders. Pharmacological inhibition of brain L-type channel isoforms, Cav1.2 and Cav1.3, may therefore be of therapeutic value. Organic calcium channels blockers are clinically used since decades for the treatment of hypertension, cardiac ischemia, and arrhythmias with a well-known and excellent safety profile. This pharmacological benefit is mainly mediated by the inhibition of Cav1.2 channels in the cardiovascular system. Despite their different biophysical properties and physiological functions, both brain channel isoforms are similarly inhibited by existing calcium channel blockers. In this review we will discuss evidence for altered L-type channel activity in human brain pathologies, new therapeutic implications of existing blockers and the rationale and current efforts to develop Cav1.3-selective compounds.

Predictors of relapse or recurrence in bipolar I disorder

OBJECTIVES

Bipolar disorder represents a major public health concern and, despite treatment, is characterized by recurring episodes of mania, depression, or mixed states. Prevention of relapse or recurrence is a primary treatment objective in the management of the disorder. The objective of the current study was to identify predictors of relapse/recurrence in patients with bipolar I disorder treated with olanzapine, lithium, divalproex, or olanzapine plus divalproex/lithium.

METHODS

Data from four clinical trials studying the efficacy of olanzapine compared to placebo and active comparators (lithium, divalproex, olanzapine plus divalproex/lithium) for bipolar I disorder were pooled for this analysis. Patients achieving remission after pharmacological treatment and entering randomized double-blind maintenance phase for 44 to 72 weeks were included. Cox Proportional Hazard models and Kaplan-Meier analyses were used to determine predictors of relapse/recurrence for the pooled data and within each treatment group.

RESULTS

A total of 929 patients meeting the criteria for remission and followed by maintenance treatment were included in this analysis, and 427 patients (46.0%) experienced symptomatic relapse/recurrence during the follow-up period. A 21-item Hamilton Depression Rating Scale (HAMD-21) total score<4, gender, rapid cycling and treatment emerged as significant predictors of relapse/recurrence and may be generalized to treatment with olanzapine and to some extent to treatment with lithium and divalproex. The results on treatment-specific predictors of relapse/recurrence are considered to be exploratory and no adjustments were made for multiple comparisons.

CONCLUSION

The major findings from this study suggest that a HAMD-21 total score<4 may be a better predictor of maintenance of remission in bipolar I patients than HAMD-21 total score<8. The prophylactic effect of olanzapine, lithium, divalproex, olanzapine plus divalproex or lithium, and placebo was assessed and baseline predictors of relapse/recurrence were identified.

Lithium: updated human knowledge using an evidence-based approach: Part I: Clinical efficacy in bipolar disorder

Although there has been a decrease in lithium use over several years, it is still recommended as a first-line mood stabilizer in all recent guidelines. It has been argued that many studies of lithium were conducted at a time when study design, assessment standards and the diagnostic criteria for patient selection were not as established as they presently are. However, recent placebo-controlled data from three-arm trials have demonstrated a definite efficacy of lithium in bipolar disorder. Regarding mania, recent trials of novel antimanic treatments (such as second-generation antipsychotics) that have included both placebo and lithium control groups have confirmed that lithium is effective in the treatment of moderate to severe manic episodes. The efficacy of lithium as monotherapy for acute bipolar depression is still controversial, but this therapy is recognized as a therapeutic option. For maintenance therapy, lithium is superior to placebo for the prevention of relapse or recurrence of mood episodes in bipolar I disorder patients with recent manic or hypomanic episodes. Lithium is more effective in preventing episodes of the manic/hypomanic type, including mixed episodes, than preventing depressive episodes. In rapid cycling patients, lithium improves clinical symptoms as efficiently as in nonrapid cycling persons, but is not likely to prevent recurrences. Finally, data from a number of studies suggest that lithium reduces the high suicide rates associated with mood disorders. A well designed cohort study and two independent meta-analyses are in agreement with this finding. In conclusion, most experts, and the most recent guidelines, continue to consider lithium as a keystone therapy of bipolar disorders.

Verapamil augmentation of lithium treatment improves outcome in mania unresponsive to lithium alone: preliminary findings and a discussion of therapeutic mechanisms

OBJECTIVES

Attenuation of protein kinase C (PKC) is a mechanism common to both established (lithium, valproate) and some novel (tamoxifen) antimanic agents. Verapamil, although primarily known as a calcium channel blocker, also has PKC inhibitory activity. Verapamil has shown antimanic activity in some but not all studies. Therefore, we investigated verapamil, used alone or as an adjunctive treatment, in manic patients who did not respond to an initial adequate trial of lithium.

METHODS

Each study phase lasted three weeks. Subjects were treated openly with lithium in Phase 1 (n = 45). Those who failed to respond were randomly assigned to double-blind treatment in Phase 2 with either verapamil (n = 10) or continued-lithium (n = 8). Phase 2 nonresponders (n = 10) were assigned to combined verapamil/lithium in Phase 3.

RESULTS

Response in Phase 2 did not differ significantly between verapamil and continued-lithium. During Phase 3, response to combined treatment was significantly better than overall response to monotherapy in Phase 2 (Fisher's Exact test, p = 0.043). Mania ratings improved during combined treatment in Phase 3 by 88.2% (linear mixed model analysis, F = 4.34, p = 0.013), compared with 10.5% improvement during Phase 2.

CONCLUSIONS

In this preliminary investigation, verapamil monotherapy did not demonstrate antimanic efficacy. By contrast, the combination of verapamil plus lithium was highly efficacious. Our findings thus suggest that verapamil may have potential utility as an adjunct to lithium. This effect may be mediated by additive actions on PKC inhibition, which may be an important mechanism for antimanic agents in general.

Non-pharmacological treatments in the management of rapid cycling bipolar disorder

BACKGROUND

Rapid cycling (RC) bipolar disorder is often treatment-resistant to pharmacotherapy. Non-pharmacological methods, however, are reasonable considerations in treatment refractory cases of bipolar patients. Thus, such methods may be useful in the management of RC, especially when drugs are not shown to be effective.

METHOD

This review is based on studies of all major non-pharmacological methods which are used in the management of bipolar disorder, by focusing on data regarding patients with a RC pattern of the illness.

RESULTS

Regarding biological treatments, for electroconvulsive therapy and sleep deprivation, there exists some evidence that they might be efficacious in RC patients for acute treatment as well as for prophylaxis from recurrences. Light therapy has not been shown to be efficacious in RC, while no published data exist for transcranial magnetic stimulation and vagus nerve stimulation. The non-biological treatments include psychotherapeutic and psychosocial interventions; these have not been tried particularly on RC patients, but their use should be expected to contribute to the overall management of the RC pattern as it does to that of mood disorder in general.

LIMITATIONS

Many data on which this review is based are drawn from case reports or non-randomised trials.

CONCLUSIONS

Non-pharmacological methods, either biological or non-biological (psychotherapies and psychoeducation), may be applied in the management of RC patients. These methods might be used in combination with the administration of drug treatment, based on the clinical experience of the physician and the individual characteristics of the patient.

Affective instability as rapid cycling: theoretical and clinical implications for borderline personality and bipolar spectrum disorders

OBJECTIVES

The Diagnostic and Statistical Manual of Mental Disorders guidelines provide only a partial solution to the nosology and treatment of bipolar disorder in that disorders with common symptoms and biological correlates may be categorized separately because of superficial differences related to behavior, life history, and temperament. The relationship is explored between extremely rapid switching forms of bipolar disorder, in which manic and depressive symptoms are either mixed or switch rapidly, and forms of borderline personality disorder in which affective lability is a prominent symptom.

METHODS

A MedLine search was conducted of articles that focused on rapid cycling in bipolar disorder, emphasizing recent publications (2001-2004).

RESULTS

Studies examined here suggest a number of points of phenomenological and biological overlap between the affective lability criterion of borderline personality disorder and the extremely rapid cycling bipolar disorders. We propose a model for the development of 'borderline' behaviors on the basis of unstable mood states that sheds light on how the psychological and somatic interventions may be aimed at 'breaking the cycle' of borderline personality disorder development. A review of pharmacologic studies suggests that anticonvulsants may have similar stabilizing effects in both borderline personality disorder and rapid cycling bipolar disorder.

CONCLUSIONS

The same mechanism may drive both the rapid mood switching in some forms of bipolar disorder and the affective instability of borderline personality disorder and may even be rooted in the same genetic etiology. While continued clinical investigation of the use of anticonvulsants in borderline personality disorder is needed, anticonvulsants may be useful in the treatment of this condition, combined with appropriate psychotherapy.

Lamotrigine and antiepileptic drugs as mood stabilizers in bipolar disorder

OBJECTIVE

To review the clinical trials literature on the use of antiepileptic drugs (AED) as mood stabilizers and to suggest an evidence-based approach when utilizing these agents in bipolar disorder.

METHOD

The literature is reviewed and subdivided into the following sections: carbamazepine and oxcarbazepine, valproate, lamotrigine, gabapentin and other AED, and discussion.

RESULTS

Data exist to support the use of carbamazepine and valproate - and to a lesser extent, oxcarbazepine - in the management of acute manic episodes associated with bipolar I disorder. Lamotrigine, gabapentin, and other AED have not demonstrated consistent anti-manic effects. Clinical trials data favor lamotrigine over all other AED in the treatment of acute bipolar I depression and in rapid cycling bipolar disorder (particularly type II), although the absence of an active comparator in these lamotrigine trials must be noted. Lamotrigine, carbamazepine, and valproate all have evidence supporting their roles as potential long-term mood stabilizers to prevent bipolar relapse, with lamotrigine having a stronger effect in the prevention of depression.

CONCLUSION

The AED are a heterogeneous group of medications with differential spectrum of efficacy in the treatment of bipolar disorder.

Dominant-submissive behavior as models of mania and depression

This review examines the ways in which dominant-subordinate behavior in animals, as determined in laboratory studies, can be used to model depression and mania in humans. Affective disorders are mood illnesses with two opposite poles, melancholia (depression) and mania that are expressed to different degrees in affected individuals. Dominance and submissiveness are also two contrasting behavioral poles distributed as a continuum along an axis with less or more dominant or submissive animals. The premise of this article is that important elements of both mania and depression can be modeled in rats and mice based on observation of dominant and submissive behavior exhibited under well defined conditions. Studies from our own research, where dominance and submissiveness are defined in a competition test and measured as the relative success of two food-restricted rats to gain access to a feeder, have yielded a paradigm that we call the Dominant Submissive Relationship (DSR). This paradigm results in two models sensitive to drugs used to treat mood disorders. Specifically, drugs used to treat mania inhibit the dominant behavior of rats gaining access to food at the expense of an opponent (Reduction of Dominant Behavior Model or RDBM), whereas antidepressants counteract the behavior of rats losing such encounters; Reduction of Submissive Behavior Model (RSBM). The validation of these models, as well as their advantages and limitations, are discussed and compared with other animal paradigms that utilize animal social behavior to model human mood disturbances.

Temporal stability of the dex/CRH test in patients with rapid-cycling bipolar I disorder: a pilot study

OBJECTIVE

To examine the hypothesis that hypothalamic-pituitary-adrenal (HPA) axis function is a trait abnormality in bipolar disorder.

METHOD

We examined HPA axis function in a pilot study of five patients with rapid-cycling bipolar disorder in both relapse and remission using the dexamethasone/corticotropin releasing hormone (dex/CRH) test.

RESULTS

The cortisol response to the dex/CRH test correlated significantly between the 2 tests (r = 0.997; p < 0.0005).

CONCLUSION

The data suggests that the cortisol response to the dex/CRH test is stable over time and independent of mood state.

Quetiapine versus placebo in combination with lithium or divalproex for the treatment of bipolar mania

Quetiapine (QTP) combined with lithium (Li) or divalproex (DVP) for the treatment of mania was evaluated in 2 double-blind, placebo-controlled studies. Patients were randomized to 3 or 6 weeks of treatment with QTP plus Li/DVP or placebo (PBO) plus Li/DVP. Quetiapine was dosed up to 800 mg/d; Li was dosed to achieve serum concentrations of 0.7-1.0 mEq/L and DVP to 50-100 microg/mL. A total of 402 patients were randomized: 197 to QTP + Li/DVP and 205 to PBO + Li/DVP. The mean quetiapine dose in responders was 492 (+/-204) mg/d. Improvement in the Young Mania Rating Scale (YMRS) at day 21 in the QTP + Li/DVP group (-15.29) was statistically superior to the PBO + Li/DVP group (-12.19) (P < 0.05). A statistically significant difference in favor of quetiapine was observed within the first week (P < 0.05). Significantly more QTP + Li/DVP patients achieved a response (> or =50% decrease in the YMRS) at day 21 (QTP + Li/DVP, 55.7%; PBO + Li/DVP, 41.6%;P < 0.01). Improvements in Clinical Global Impression-Bipolar Severity of Illness scores by day 21 were also significantly greater in QTP + Li/DVP-treated patients (-1.59) versus PBO + Li/DVP (-1.19) (P < 0.01). Common adverse events (> or =5% and twice that in the PBO + Li/DVP group) in the QTP + Li/DVP group were somnolence, dry mouth, and asthenia. Quetiapine combined with Li/DVP was not associated with extrapyramidal symptoms (including akathisia) or emergent depression. More QTP + Li/DVP-treated patients completed the trial, and there was no difference in discontinuation rates due to adverse events between the two groups. Quetiapine, in combination with lithium or divalproex, is well tolerated and has superior efficacy to lithium or divalproex alone in the treatment of bipolar mania.

Monotherapy treatment of bipolar disorder with levetiracetam

Bipolar patients with early-onset, comorbid substance abuse, rapid cycling, and mixed episodes are difficult to treat and frequently require rational polypharmacy. When polypharmacy is unsuccessful, the clinician must consider the off-label use of newer psychotropics. Levetiracetam is a novel anticonvulsant with antikindling, inhibitory, and neuroprotective properties that is effective in an animal model of mania. This case report describes a patient with treatment-resistant rapid cycling bipolar disorder who failed 15 psychotropics, individually or in various combinations (maximum of 6), but ultimately responded to levetiracetam monotherapy and remained without bipolar features during 1 year of maintenance treatment, excluding 1 week during which the patient was medicine noncompliant. Further, methylphenidate used to treat comorbid attention deficit disorder did not precipitate manic features. Levetiracetam should be further studied for its potential use in the treatment of bipolar disorders.

Efficacy of atypical antipsychotics in mood disorders

Lithium and valproate are well recognized as mood-stabilizing medications. However, a significant number of patients with bipolar disorder do not respond to or cannot tolerate the side effects of these drugs. As a result, a search for safer and more effective mood stabilizers for the treatment of bipolar disorder is ongoing. Antipsychotic medications have long been used as adjunctive therapy in combination with mood-stabilizing medications. Although conventional neuroleptics (also known as typical antipsychotics) such as haloperidol or chlorpromazine are effective antimanic agents, they do not appear to have any efficacy in treating comorbid depressive symptoms. Furthermore, typical antipsychotics are associated with a number of well-known side effects, such as extrapyramidal symptoms and tardive dyskinesia. Mood-stabilizing effects have recently been reported for a number of newer "atypical" antipsychotics that have a broader spectrum of efficacy and better safety profiles than the typical antipsychotics. The results of several clinical trials suggest that atypical antipsychotics, including risperidone, olanzapine, ziprasidone, and quetiapine, are effective for the treatment of acute mania, and open-label studies suggest that atypical antipsychotics may have long-term mood-stabilizing effects.

Gabapentin in geriatric mania

There is little available information on anticonvulsant treatment of mania in elderly patients. Seven elderly patients, each in a manic episode, were treated with gabapentin. All 7 patients experienced improvement in manic symptoms, with minimal to no side effects. They received gabapentin in combination with antipsychotic medications, and in 1 case in combination with valproate. Gabapentin appears to be a safe and effective treatment in geriatric mania when combined with antipsychotic medications or valproate. Gabapentin appears to be well tolerated with no major adverse drug interactions or side effects in elderly manic patients. This case series suggests that controlled studies are warranted to examine gabapentin's efficacy and side effects, particularly as an adjunctive medication, in geriatric mania.

Coadministration of gabapentin or MK-801 with lamotrigine slows tolerance to its anticonvulsant effects on kindled seizures

The development of tolerance to therapeutic effects of antiepileptic drugs can be a problem in the treatment of epilepsy, bipolar disorder, and pain syndromes. In the present study, acute treatment with the new antiepileptic drug lamotrigine (LTG, 15 mg/kg) markedly suppressed seizure stage and seizure duration in amygdala-kindled rats; but this antiseizure effect was rapidly lost following 4-8 days of repeated treatment. When gabapentin (GBP, 20 mg/kg) was coadministered with LTG, the ability of LTG to suppress seizure stage, seizure duration, and after-discharge (AD) duration was markedly extended. In addition, GBP coadministration with LTG decreased the number of animals that developed LTG-related running fits (Stage 6 seizures) and lengthened the number of days required to develop running fits or complete tolerance. Neither acute nor repeated treatment with MK-801 (0.3 mg/kg), a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, had effects on kindled seizures. However, cotreatment with MK-801 markedly extended the anticonvulsant effects of LTG on the three seizure indices and reduced running fits. These data indicate that cotreatment with either GBP or MK-801 slows tolerance development to the anticonvulsant effects of LTG on kindled seizures. Therapeutic implications of the present study remain to be explored.

The benzodiazepine partial inverse agonist Ro15-4513 alters anticonvulsant and lethal effects of carbamazepine in amygdala-kindled rats

Ro15-4513 (ethyl-8-azido-5,6-dihydro-5methyl-6-oxo-4H-imidazo-[1,5-a]-1,4-benzodiazepine-3-carboxylate), a benzodiazepine partial inverse agonist of the GABA(A) receptor, is known to protect against alcohol toxicities. The present study was designed to determine the role of Ro15-4513 in preventing anticonvulsant, toxic, and lethal effects of carbamazepine (CBZ) in amygdala-kindled rats. Acute treatment with CBZ (25 mg/kg, i.p.) produced anticonvulsant effects in fully kindled rats characterized by a significant decrease in afterdischarge and seizure duration and stage. Repeated administration of this high dose of CBZ induced sedation and high (56%) lethality. The anticonvulsant and sedative effects of CBZ were strikingly suppressed by pretreatment with Ro15-4513 (2.5 and 5 mg/kg, i.p.), and there was no mortality in animals co-administrated with Ro15-4513 during the entire experimental period. These results indicate that Ro15-4513 protects against CBZ-induced sedation and lethality, while suppressing the anticonvulsant effects of CBZ, suggesting a role for the GABA(A) receptor in CBZ efficacy and side effects. The potential clinical implications for CBZ-induced toxicity and overdose remain to be explored.

Rapid cycling bipolar disease: new concepts and treatments

Having been recognized by Kraeplin at the beginning of the 20th century, rapid cycling was first described as a specific entity by Dunner et al. in 1974. The prevalence of rapid cycling ranges from 12% to 20% in patients with bipolar disorder who are not selected for a high rate of cycling.

Maternal antiepileptic drug use and effects on fetal development

Many pregnant women take antiepileptic medications, and concern has arisen about the risks this poses to the fetus. It has been debated whether the causative agent is the medication or the underlying maternal disorder. Review of the recent literature indicates that the effects seem to be from the medications themselves. The frequency of malformations is about two to three-fold above the background rate and is dose-related for some of the medications. There seem to be effects on birth weight, length, and head circumference caused by at least some of the medications. The risks are greater when more than one medication is used. Cognitive effects from the medications have been shown, although these effects are of lower magnitude than previously reported. More investigation needs to be done to determine the exact risks of each individual medication, especially the newer ones. Studies on underlying mechanisms indicate potential genetic susceptibility and altered developmental gene expression patterns.

Response to lithium maintenance treatment in bipolar disorders: comparison of women and men

OBJECTIVES

Possible sex differences in responses to mood-stabilizing treatment remain poorly defined. Since women with bipolar disorder reportedly have more features that may predict a poor prognosis (depression and rapid cycling), we tested the hypothesis that women respond less well to lithium maintenance treatment.

METHODS

Clinical characteristics of 360 women and men with DSM-IV bipolar I or II disorder were compared before and during clinical lithium maintenance monotherapy in a mood disorders clinic by preliminary bivariate comparisons, multivariate analysis, and survival analysis of time stable during treatment.

RESULTS

Women (n = 229) versus men (n = 131) were: more likely to have type II disorder (1.6 times), 3.2 years older at illness onset, more often depressed-before-manic (1.4 times), considered unipolar depressive 1.9 years longer and started maintenance treatment 5.5 years later. However, women differed little from men before treatment in overall morbidity, average episode frequency and risk of suicide attempts. Contrary to prediction, women showed non-significantly superior responses to lithium treatment, and a significant 60% longer median time before a first recurrence during treatment, despite 7% lower average serum lithium concentrations.

CONCLUSIONS

Women were diagnosed as bipolar later than men with corresponding delay of lithium maintenance treatment that proved to be at least as effective as in men.