Relevance of new and newly rediscovered anticonvulsants for atypical forms of bipolar disorder

Management of bipolar depression with lamotrigine: an antiepileptic mood stabilizer

The efficacy of lamotrigine in the treatment of focal epilepsies have already been reported in several case reports and open studies, which is thought to act by inhibiting glutamate release through voltage-sensitive sodium channels blockade and neuronal membrane stabilization. However, recent findings have also illustrated the importance of lamotrigine in alleviating the depressive symptoms of bipolar disorder, without causing mood destabilization or precipitating mania. Currently, no mood stabilizers are available having equal efficacy in the treatment of both mania and depression, two of which forms the extreme sides of the bipolar disorder. Lamotrigine, a well established anticonvulsant has received regulatory approval for the treatment and prevention of bipolar depression in more than 30 countries worldwide. Lamotrigine, acts through several molecular targets and overcomes the major limitation of other conventional antidepressants by stabilizing mood from “below baseline” thereby preventing switches to mania or episode acceleration, thus being effective for bipolar I disorder. Recent studies have also suggested that these observations could also be extended to patients with bipolar II disorder. Thus, lamotrigine may supposedly fulfill the unmet requirement for an effective depression mood stabilizer.

Impact of mood stabilizers and antiepileptic drugs on cytokine production in-vitro

Changes within the immune system have been reported to contribute to the pathophysiology of bipolar disorder and epilepsy. Interestingly, overlapping results regarding the cytokine system have been found for both diseases, namely alterations of interleukins IL-1β, IL-2, IL-4, IL-6, and tumor necrosis factor-α (TNF-α). However, the effect of mood stabilizers and antiepileptic drugs (AEDs) on these cytokines has not been systematically evaluated, and their effect on IL-17 and IL-22, other immunologically important cytokines, has not been reported. Therefore, we systematically measured levels of IL-1β, IL-2, IL-4, IL-6, IL-17, IL-22 and TNF-α in stimulated blood of 14 healthy female subjects in a whole blood assay using the toxic shock syndrome toxin TSST-1 as stimulant. Blood was supplemented with the mood stabilizers or antiepileptic drugs primidone (PRM), carbamazepine (CBZ), levetiracetam (LEV), lamotrigine (LTG), valproic acid (VPA), oxcarbazepine (OXC), topiramate (TPM), phenobarbital (PB), lithium, or no drug. IL-1β production was significantly decreased by PRM, CBZ, LEV, LTG, OXC, PB and lithium. IL-2 significantly decreased by PRM, CBZ, LEV, LTG, VPA, OXC, TPM and PB. IL-22 significantly increased by PRM, CBZ, LEV, OXC, TPM and lithium and decreased by VPA. TNF-α production significantly decreased under all applied drugs. The mechanism of action and side effects of mood stabilizers and AEDs may involve modulation of IL-1β, IL-2, IL-22 and TNF-α signaling pathways. IL-22 may be a research target for specific therapeutic effects of mood stabilizers and AEDs. These drugs might influence cytokine production by modulating ion channels and γ-aminobutyric acid (GABA) receptors of immune cells.

The World Federation of Societies of Biological Psychiatry (WFSBP) Guidelines for the Biological Treatment of Bipolar Disorders: Update 2010 on the treatment of acute bipolar depression

OBJECTIVES

These guidelines are based on a first edition that was published in 2002, and have been edited and updated with the available scientific evidence until September 2009. Their purpose is to supply a systematic overview of all scientific evidence pertaining to the treatment of acute bipolar depression in adults.

METHODS

The data used for these guidelines have been extracted from a MEDLINE and EMBASE search, from the clinical trial database clinicaltrials.gov, from recent proceedings of key conferences, and from various national and international treatment guidelines. Their scientific rigor was categorised into six levels of evidence (A-F). As these guidelines are intended for clinical use, the scientific evidence was finally assigned different grades of recommendation to ensure practicability.

RESULTS

We identified 10 pharmacological monotherapies or combination treatments with at least limited positive evidence for efficacy in bipolar depression, several of them still experimental and backed up only by a single study. Only one medication was considered to be sufficiently studied to merit full positive evidence.

CONCLUSIONS

Although major advances have been made since the first edition of this guideline in 2002, there are many areas which still need more intense research to optimize treatment. The majority of treatment recommendations is still based on limited data and leaves considerable areas of uncertainty.

The World Federation of Societies of Biological Psychiatry (WFSBP) guidelines for the biological treatment of bipolar disorders: update 2009 on the treatment of acute mania

These updated guidelines are based on a first edition that was published in 2003, and have been edited and updated with the available scientific evidence until end of 2008. Their purpose is to supply a systematic overview of all scientific evidence pertaining to the treatment of acute mania in adults. The data used for these guidelines have been extracted from a MEDLINE and EMBASE search, from the clinical trial database clinicaltrials.gov, from recent proceedings of key conferences, and from various national and international treatment guidelines. Their scientific rigor was categorised into six levels of evidence (A-F). As these guidelines are intended for clinical use, the scientific evidence was finally asigned different grades of recommendation to ensure practicability.

Development of psychosis in patients with epilepsy treated with lamotrigine: report of six cases and review of the literature

Lamotrigine (LTG) is a generally well-tolerated antiepileptic drug (AED) with broad-spectrum efficacy in several forms of partial and generalized epilepsy and is also licensed for use in bipolar disorder in several countries. We describe six patients who developed a psychotic disorder--in most, but not all, cases schizophrenia-like in character--under treatment with LTG, within a group of about 1400 patients treated with this drug in our center. This indicates that psychosis is a rare adverse event under LTG treatment. On the background of available drug serum levels, we suggest, in particular, an intrinsic or toxic psychotogenic effect of LTG. Possible risk factors seem to be psychiatric comorbidity and temporal lobe pathology. The described phenomenon is discussed within the context of possible psychotogenic effects of other AEDs.

Pharmacological treatment of bipolar disorder among children and adolescents

There is growing recognition that bipolar disorder frequently first presents in adolescence. Preadolescents with volatile behavior and severe mood swings also comprise a large group of patients whose difficulties may lie within the bipolar spectrum. However, the preponderance of scientific effort and clinical trials for this condition has focused on adults. This review summarizes the complexity of bipolar disorder and diagnosis of the disease among young people. It proceeds to review the principles of pharmacotherapy, assess current treatment options and to highlight areas where evidence-based guidance is lacking. Recent developments have enlarged the range of potential treatments for bipolar disorder. Nonetheless, differences in the phenomenology, course and sequelae of bipolar disorder among young people compel greater attention to the benefits and liabilities of therapy for those affected by this illness' early onset. By summarizing current research and opinion on diagnostic issues and treatment approaches, this review aims to provide an update on a clinically important yet controversial topic.

Psychopharmacology of topiramate: from epilepsy to bipolar disorder

Topiramate (TPM) is one of the novel antiepileptic drugs and exhibits a wide range of mechanisms of action. Efficacy of TPM has been demonstrated in partial-onset seizures and primary generalized seizures in adults and children, as both monotherapy and adjunctive therapy. More recently, TPM has been proposed as an add-on treatment for patients with lithium-resistant bipolar disorder, especially those displaying rapid-cycling and mixed states. This paper reviews the multiple mechanisms of action and the tolerability profile of TPM in the light of its therapeutic potential in affective disorders. Studies of TPM in bipolar disorder are evaluated, and the efficacy and tolerability issues as a mood stabilizing agent are discussed.

Phenytoin poisoning

Phenytoin toxicity may result from intentional overdose, dosage adjustments, drug interactions, or alterations in physiology. Intoxication manifests predominantly as nausea, central nervous system dysfunction (particularly confusion, nystagmus, and ataxia), with depressed conscious state, coma, and seizures occurring in more severe cases. Cardiac complications such as arrhythmias and hypotension are rare in cases of phenytoin ingestion, but they may be seen in parenteral administration of phenytoin or fosphenytoin. Deaths are unlikely after phenytoin intoxication alone. A greatly increased half-life in overdose due to zero-order pharmacokinetics can result in a prolonged duration of symptoms and thus prolonged hospitalization with its attendant complications. The mainstay of therapy for a patient with phenytoin intoxication is supportive care. Treatment includes attention to vital functions, management of nausea and vomiting, and prevention of injuries due to confusion and ataxia. There is no antidote, and there is no evidence that any method of gastrointestinal decontamination or enhanced elimination improves outcome. Activated charcoal should be considered if the patient presents early; however, the role of multiple-dose activated charcoal is controversial. Experimental studies have proven increased clearance rates, but this effect has not been translated into clinical benefit. There is no evidence that any invasive method of enhanced elimination (such as plasmapheresis, hemodialysis, or hemoperfusion) provides any benefit. This article provides an overview of phenytoin pharmacokinetics and the clinical manifestations of toxicity, followed by a detailed review of the various treatment modalities.

Phenytoin reverses the chronic stress-induced impairment of memory consolidation for water maze training and depression of LTP in rat hippocampal CA1 region, but does not affect motor activity

Previous studies have shown that phenytoin can protect hippocampal structure from damage by chronic stress, while whether it can reverse the hippocampal malfunction induced by chronic stress is unknown. We investigated the effects of phenytoin on motor activity of stressed rats and on the long-term memory of water maze spatial training, which is known to depend on hippocampal function. We also explored whether phenytoin could protect long-term potentiation (LTP) in hippocampal CA1 region from depression of chronic stressed rats. Isolated hippocampal slices of rats were used to observe the changes of LTP in hippocampal CA1 field with electrophysiological technique. The results showed that the motor activity of chronic forced-swimming rats was markedly higher than that of control rats, and phenytoin could not affect this change. The performance of water maze spatial training indicated that chronic stress damages long-term memory but not short-term memory, and phenytoin could reverse this long-term memory deficit. The increases of LTP after HFS in control and stress-phenytoin groups were significantly greater than those in stress-saline group (P < 0.05). There were no significant differences between control group and stress-phenytoin group (P > 0.05) and between control and control-phenytoin groups (P > 0.05). These findings provided the first evidence with behavioral and electrophysiological technique that phenytoin could reverse the hippocampal-dependent memory deficit and depression of LTP induced by chronic stress, which may be helpful for exploring the pathogenesis and improving the therapy of depression.

The World Federation of Societies of Biological Psychiatry (WFSBP) guidelines for the biological treatment of bipolar disorders, part III: maintenance treatment

As with the two preceding guidelines of this series, these practice guidelines for the pharmacological maintenance treatment of bipolar disorder were developed by an international task force of the World Federation of Societies of Biological Psychiatry (WFSBP). Their purpose is to supply a systematic overview of all scientific evidence relating to maintenance treatment. The data used for these guidelines were extracted from a MEDLINE and EMBASE search, from recent proceedings from key conferences and various national and international treatment guidelines. The scientific justification of support for particular treatments was categorised into four levels of evidence (A-D). As these guidelines are intended for clinical use, the scientific evidence was not only graded, but also reviewed by the experts of the task force to ensure practicality.

A review of acute treatments for bipolar depression

Bipolar patients generally spend much more time in the depressed phase of their illness than the manic phase, and there are many more bipolar type II and bipolar spectrum disorder patients than there are bipolar type I. Additionally, there is a significant risk of suicide in bipolar patients when depressed. The treatment of the depressed phase of bipolar disorder is therefore a matter of some priority. Here, we review current evidence supporting the use of five groups of treatments: anti-depressants; lithium; anti-convulsants (valproate, and carbamazepine, lamotrigine, gabapentin); anti-psychotics; and other treatments (electroconvulsive therapy, benzodiazepines, sleep-deprivation, and dopamine agonists). From this review, it is apparent that the literature regarding the treatment of bipolar depression is significantly limited in several key areas. Nonetheless, from the evidence currently available, the treatments with the best evidence for efficacy are selective serotonin reuptake inhibitors (SSRIs) and lamotrigine. There is also some evidence in favour of bupropion and moclobemide. Although lithium and olanzapine monotherapies can also be beneficial, they appear less efficacious than antidepressants. One of the major concerns about treatment with antidepressants has been the risk of precipitating a switch into mania. However, recent studies suggest that, if a mood stabilizer and antidepressant are given concurrently, then the risk of switching is minimized. There is also recent evidence for an independent antidepressant action for at least one atypical antipsychotic. Therefore, the conclusion from this review, in contrast to previous suggestions, is that a combination of an atypical antipsychotic and either an SSRI or lamotrigine may provide a useful first-line treatment for depressed bipolar disorder patients. Further research is clearly required to examine this approach and compare it with other possible treatment options.

Shared mechanisms of antidepressant and antiepileptic treatments: drugs and devices

Many treatments for the epilepsies and affective disorder share the properties of seizure suppression and mood stabilization. Moreover, affective disorders and the epilepsies appear to share partially similar pathogenic mechanisms. A component of the shared predisposition appears to arise from noradrenergic and serotonergic deficits. Increasing evidence supports the hypothesis that noradrenergic and/or serotonergic elevation is a mechanism of therapeutic benefit shared by most antidepressants and many antiepileptic medications. Medication induced alterations in GABAergic, glutamatergic, and CRH (corticotropin releasing hormone) containing neurons may also contribute to the shared therapeutic properties of antidepressant and antiepileptic medications.

Unidirectional Cross-tolerance from Levetiracetam to Carbamazepine in Amygdala-kindled Seizures

PURPOSE

Tolerance is a potential problem in long-term anticonvulsant therapy of epilepsy, bipolar disorder, and neuropathic pain. The present study was designed to determine whether cross-tolerance occurs between levetiracetam (LEV) and carbamazepine (CBZ) in amygdala-kindled rats.

METHODS

Male Sprague-Dawley rats were implanted with an electrode into the left amygdala. While kindling stimulation was started, animals received repeated treatment (i.p.) with saline (n = 7) or LEV (150 mg/kg, n = 8). Saline-injected rats were subsequently challenged with a single dose of 150 mg/kg LEV when full kindling developed (stage > or =4). Both groups of rats were then administered long-term CBZ (5 mg/kg) until rats developed complete tolerance. All CBZ-tolerant rats were subsequently re-exposed to LEV (150 mg/kg) for an additional 10 consecutive days.

RESULTS

Repeated LEV treatment significantly suppressed the increase in seizure stage, seizure duration, and afterdischarge duration induced by amygdala stimulation, markedly increasing the number of stimulations to achieve a kindling major motor seizure. The LEV challenge produced a more robust suppression of seizure stage in saline-injected rats compared with LEV-treated animals. CBZ treatment markedly suppressed fully kindled seizures in rats initially injected with saline, and then anticonvulsant tolerance rapidly developed after 3-4 days of repeated treatment. In contrast, rats that had initially received repeated LEV treatment did not show a response to treatment with CBZ (5 mg/kg). When CBZ-tolerant rats were subsequently exposed to LEV (150 mg/kg), noticeable anticonvulsant effects were observed; but these were gradually lost with increasing numbers of LEV exposures.

CONCLUSIONS

Whereas LEV shows potent antiepileptogenic and anticonvulsant effects in amygdala-kindled rats, its repeated treatment induces anticonvulsant tolerance and unidirectional cross-tolerance to CBZ. In contrast, anticonvulsant tolerance to CBZ does not transfer to LEV. The mechanistic implications of the present results for clinical therapeutics remain to be evaluated.

Common pathogenic mechanisms between depression and epilepsy: an experimental perspective

Affective disorders and the epilepsies appear to share partially similar pathogenic mechanisms. Predisposition to both disorders is determined genetically and experientially. A component of the shared predisposition appears to arise from noradrenergic and serotonergic deficits. Shared GABAergic deficits coupled with CRHergic and glutamatergic excesses may trigger and maintain seizures as well as dysfunctional affective episodes, albeit via dissimilar neuronal interplay.