Newer antiepileptic drugs in bipolar disorder: rationale for use and role in therapy

Neuroprotective Properties of Antiepileptics: What are the Implications for Psychiatric Disorders?

Since the discovery of the first antiepileptic compound, increasing attention has been paid to antiepileptic drugs (AEDs), and recently, with the understanding of the molecular mechanism underlying cells death, a new interest has revolved around a potential neuroprotective effect of AEDs. While many neurobiological studies in this field have focused on the protection of neurons, growing data are reporting how exposure to AEDs can also affect glial cells and the plastic response underlying recovery; however, demonstrating the neuroprotective abilities of AEDs remains a changeling task. The present work aims to summarize and review the literature available on the neuroprotective properties of the most commonly used AEDs. Results highlighted how further studies should investigate the link between AEDs and neuroprotective properties; while many studies are available on valproate, results for other AEDs are very limited and the majority of the research has been carried out on animal models. Moreover, a better understanding of the biological basis underlying neuro-regenerative defects may pave the way for the investigation of further therapeutic targets and eventually lead to an improvement in the actual treatment strategies.

Lamotrigine as a mood stabilizer: insights from the pre-clinical evidence

INTRODUCTION

Lamotrigine (LTG) is a well-established anticonvulsant that is also approved for the prevention of mood relapses in bipolar disorder. However, the mechanisms underlying LTG mood stabilizing effects remain unclear. Areas covered: Herein, the pre-clinical evidence concerning LTG's' mode of action in depression and mania is reviewed. Bottlenecks and future perspectives for this expanding and promising field are also discussed. Pre-clinical studies have indicated that neurotransmitter systems, especially serotoninergic, noradrenergic and glutamatergic, as well as non-neurotransmitter pathways such as inflammation and oxidative processes might play a role in LTG's antidepressant effects. The mechanisms underlying LTG's anti-manic properties remain to be fully explored, but the available pre-clinical evidence points out to the role of glutamatergic neurotransmission, possibly through AMPA-receptors. Expert opinion: A major limitation of current pre-clinical investigations is that there are no experimental models that recapitulate the complexity of bipolar disorder. Significant methodological differences concerning time and dose of LTG treatment, administration route, animal strains, and behavioral paradigms also hamper the reproducibility of the findings, leading to contradictory conclusions. Moreover, the role of other mechanisms (e.g. inositol phosphate and GSK3β pathways) implicated in the mode of action of different mood-stabilizers must also be consolidated with LTG.

Gabapentin for Off-Label Use: Evidence-Based or Cause for Concern?

Gabapentin is widely used in the United States for a number of off-label indications, often as an alternative to opioid therapy. Increasing evidence has emerged suggesting that gabapentin may not be as benign as once thought and may be associated with substance abuse in concert with opioids. With concerns for safety mounting, it is prudent to examine the efficacy of gabapentin across its many uses to understand the risk-benefit balance. Reviews on off-label indications such as migraine, fibromyalgia, mental illness, and substance dependence have found modest to no effect on relevant clinical outcomes. This high-quality evidence has often been overshadowed by uncontrolled studies and limited case reports. Furthermore, the involvement of gabapentin in questionable marketing schemes further calls its use into question. Overall, clinicians should exercise rigorous appraisal of the available evidence for a given indication, and researchers should conduct larger, higher-quality studies to better assess the efficacy of gabapentin for many of its off-label uses.

Clinical Guidelines on Long-Term Pharmacotherapy for Bipolar Disorder in Children and Adolescents

Bipolar disorder is a severe affective disorder which can present in adolescence, or sometimes earlier, and often requires a pharmacotherapeutic approach. The phenomenology of bipolar disorder in children and adolescents appears to differ from that of adult patients, prompting the need for specific pharmacotherapy guidelines for long-term management in this patient population. Current treatment guidelines were mainly developed based on evidence from studies in adult patients, highlighting the requirement for further research into the pharmacotherapy of children and adolescents with bipolar disorder. This review compares and critically analyzes the available guidelines, discussing the recommended medication classes, their mechanisms of action, side effect profiles and evidence base.

Synthesis of new 2,5-disubstituted-1,3,4-thiadiazole derivatives and their in vivo anticonvulsant activity

A series of 2,5-disubstituted-1,3,4-thiadiazole derivatives were synthesized by the reaction of 3-(2-cyanopropan-2-yl)-N-(5-(piperazine-1-yl)-1,3,4-thiadiazol-2-yl)benzamide with various sulfonyl chlorides and evaluated for their anticonvulsant activity in MES test. Rotorod method was employed to determine the neurotoxicity. The purity of the compounds is confirmed on the basis of their elemental analysis. The structures of all the new compounds are established on the basis of 1H NMR and mass spectral data. Out of fifteen compounds, three were found to be potent anticolvunstants. The same compounds showed no neurotoxicity at the maximum dose administered (100 mg/kg).

Pharmacological treatment of neuropathic cancer pain: a comprehensive review of the current literature

Neuropathic cancer pain (NCP), commonly encountered in clinical practice, may be cancer-related, namely resulting from nervous system tumor invasion, surgical nerve damage during tumor removal, radiation-induced nerve damage and chemotherapy-related neuropathy, or may be of benign origin, unrelated to cancer. A neuropathic component is evident in about 1/3 of cancer pain cases. Although from a pathophysiological perspective NCP may differ from chronic neuropathic pain (NP), such as noncancer-related pain, clinical practice, and limited publications have shown that these two pain entities may share some treatment modalities. For example, co-analgesics have been well integrated into cancer pain-management strategies and are often used as First-Line options for the treatment of NCP. These drugs, including antidepressants and anticonvulsants, are recommended by evidence-based guidelines, whereas, others such as lidocaine patch 5%, are supported by randomized, controlled, clinical data and are included in guidelines for restricted conditions treatment. The vast majority of these drugs have already been proven useful in the management of benign NP syndromes. Treatment decisions for patients with NP can be difficult. The intrinsic difficulties in performing randomized controlled trials in cancer pain have traditionally justified the acceptance of drugs already known to be effective in benign NP for the management of malignant NP, despite the lack of relevant high quality data. Interest in NCP mechanisms and pharmacotherapy has increased, resulting in significant mechanism-based treatment advances for the future. In this comprehensive review, we present the latest knowledge regarding NCP pharmacological management.

Anticonvulsants in the treatment of major depressive disorder: an overview

Major depressive disorder (MDD) is highly prevalent, potentially disabling, and sometimes fatal. Antidepressants (ADs) have improved its treatment, but incomplete response, sustained morbidity, recurrences, agitation, substance abuse, excess medical mortality, and suicide remain unsolved problems among mood disorder patients. AD treatment itself sometimes induces adverse behavioral responses. Several anticonvulsants (ACs) used to treat bipolar disorder (BPD) might also be of value for MDD. Accordingly, we reviewed published reports on ACs for MDD, identifying studies by computerized searches. We excluded reports dealing only with BPD patients or with sedatives, classified trials by design quality, and evaluated treatment of acute episodes and recurrences of adult MDD. We found 36 reports involving 41 relevant trials of carbamazepine (12 trials), valproate (11), lamotrigine (9), gabapentin (3), topiramate (3), phenytoin (2), and tiagabine (1). They include 9 blinded, controlled trials (of 28-70 days), involving carbamazepine (3 trials), lamotrigine (3), phenytoin (2), or topiramate (1) as primary treatments (5) or AD adjuncts (4). Some of these trials, as well as 7 of lesser quality, suggest benefits of carbamazepine, lamotrigine, and valproate, mainly as adjuncts to ADs. Another 20 anecdotes or small trials further suggest that these ACs might be useful as AD adjuncts-specifically to treat irritability or agitation in MDD. Overall, these reports provide suggestive evidence of beneficial effects of carbamazepine, lamotrigine, and valproate that require further study, especially for long-term adjunctive use, particularly in patients with recurring MDD with prominent irritability or agitation.

How reviews covered the unfolding scientific story of gabapentin for bipolar disorder

BACKGROUND

Despite the lack of randomized controlled trials (RCTs), gabapentin use increased rapidly in the 1990s for mental health conditions. Subsequent RCTs did not demonstrate efficacy for bipolar disorder (BD). We examined the characteristics of review articles to determine their potential role in the growth of gabapentin for BD.

METHODS

We searched MEDLINE, the International Pharmaceutical Abstracts and LexisNexis for review articles or commentaries examining the role of gabapentin for BD. Electronic searches were supplemented by manual searches of reference lists. Articles were abstracted for the types of evidence cited, source of evidence, the proportion of available RCTs cited and narrative blurbs discussing the role of gabapentin for BD. Review articles were classified as narrative versus systematic and positive, neutral or negative regarding the role of gabapentin in BD.

RESULTS

We included 27 review articles published between 1998 and 2008, but no commentaries met eligibility criteria. Most did not describe potential conflicts of interest or a funding source, and the 3 systematic reviews were of low quality. The 11 reviews published prior to the first RCT of gabapentin for BD cited uncontrolled trials or case series (n=9), basic science (n=6), chart reviews (n=3) or unpublished RCTs (n=2). Six recommended gabapentin, 3 were neutral and 2 were negative. The 16 articles published after the first gabapentin RCT continued to cite uncontrolled trials and basic science; only 5 cited all the available RCTs. However, more of these reviews (n=10) reached negative conclusions about the role of gabapentin for BD.

CONCLUSIONS

Narrative and low-quality systematic reviews, principally those published prior to RCTs, may have contributed to the growth of gabapentin use for BD. High-quality systematic reviews are needed to inform clinicians and policymakers about the effectiveness of new treatments.

Anticonvulsant treatments of dysphoric mania: a trial of gabapentin, lamotrigine and carbamazepine in Iran

The treatment of dysphoric mania is challenging given the need to treat symptoms of both depression and mania simultaneously without provoking any clinical exacerbation. The newer antiepileptic drugs such as gabapentin, lamotrogine, and carbamazepine are often used as adjuncts to either lithium or valproic acid in the treatment of bipolar disorder. We decided to undertake a monotherapy trial because previous evidence suggested mixed states may be more responsive to anticonvulsants than more traditional antimanic agents. 51 patients with a DSM IV diagnosis of dysphoric mania were randomized to three groups comprising gapbapentin, lamotrogine or carbamazepine and followed for 8 weeks. Psychiatric diagnosis was verified by the structural clinical interview for the DSM-IV (SCID). The MMPI-2 in full was used to assess symptoms at baseline and 8 weeks. All three groups showed significant changes in MMPI-2 scores for depression and mania subscales. Gabapentin showed the greatest change in depression symptom improvement relative to lamotrogine and carbamazepine, respectively. Although manic symptoms improved overall, here were no differences between groups in the degree of manic symptom improvement.

Reduction in occipital cortex gamma-aminobutyric acid concentrations in medication-free recovered unipolar depressed and bipolar subjects

BACKGROUND

Studies using proton magnetic resonance spectroscopy (MRS) have indicated that unmedicated, acutely depressed patients have decreased levels of gamma-aminobutyric acid (GABA) in occipital cortex. Cortical levels of glutamate (Glu) may be increased, although these data are less consistent. The aim of this study was to use MRS to determine whether changes in GABA and Glu levels were present in patients with mood disorders who had recovered and were no longer taking medication.

METHODS

An [1H]-MRS was used to measure levels of GABA, of the combined concentration of Glu and glutamine (Gln), and of N-acetylaspartate (NAA) in occipital cortex in medication-free, fully recovered subjects with a history of recurrent unipolar depression (n = 15), bipolar disorder (n = 16), and a group of healthy controls (n = 18).

RESULTS

Occipital levels of GABA and NAA were significantly lower in recovered depressed and bipolar subjects than in healthy controls, whereas Glu +Gln concentrations were higher.

CONCLUSIONS

Our data suggest that recovered unmedicated subjects with a history of mood disorder have changes in cortical concentrations of GABA, NAA, and Glu +Gln. These biochemical abnormalities may be markers of a trait vulnerability to mood disorder, rather than neurochemical correlates of an abnormal mood state.

The effects of central nervous system-active valproic acid constitutional isomers, cyclopropyl analogs, and amide derivatives on neuronal growth cone behavior

Valproic acid (VPA) is an effective antiepileptic drug with an additional activity for the treatment of bipolar disorder. It has been assumed that both activities arise from a common target. At the molecular level, VPA targets a number of distinct proteins that are involved in signal transduction. VPA inhibition of inositol synthase reduces the cellular concentration of myo-inositol, an effect common to the mood stabilizers lithium and carbamazepine. VPA inhibition of histone deacetylases activates Wnt signaling via elevated beta-catenin expression and causes teratogenicity. Given the VPA chemical structure, it may be possible to design VPA derivatives and analogs that modulate specific protein targets but leave the others unaffected. Indeed, it has been shown that some nonteratogenic VPA derivatives retain antiepileptic and inositol signaling effects. In this study, we describe a further set of VPA analogs and derivatives that separate anticonvulsant activity from effects on neuronal growth cone morphology. Lithium, carbamazepine, and VPA induce inositol-dependent spread of neuronal growth cones, providing a cell-based assay that correlates with mood-stabilizing activity. We find that two constitutional isomers of VPA, propylisopropylacetic acid and diisopropylacetic acid, but not their corresponding amides, and N-methyl-2,2,3,3-tetramethyl-cyclopropanecarboaxamide are more effective than VPA in increasing growth cone spreading. We show that these effects are associated with inositol depletion, and not changes in beta-catenin-mediated Wnt signaling. These results suggest a route to a new generation of central nervous system-active VPA analogs that specifically target bipolar disorder.

Therapeutic Management of Chronic Neuropathic Pain: An Examination of Pharmacologic Treatment

Neuropathic pain is defined as pain caused by a lesion in the nervous system and is common in clinical practice. Diagnosis can be difficult. Recommendations for first-line pharmacologic treatments are based on positive results from multiple, randomized, controlled trials, and recommendations for second-line pharmacologic treatments are based on the positive result of a single, randomized, controlled trial or inconsistent results of multiple, randomized, controlled trials. The results of published trials and clinical experience provide the foundation for specific recommendations for first-line treatments, which include gabapentin, 5% lidocaine patch, opioid analgesics, tramadol hydrochloride, and tricyclic antidepressants (TCAs). Gabapentin (up to 3,600 mg/day) significantly reduced pain compared with placebo; improvements in sleep, mood, and quality of life were also demonstrated. Adverse effects of gabapentin include somnolence and dizziness, and, less commonly, gastrointestinal symptoms and mild peripheral edema. Thus, monitoring and dosage adjustment are required, without discontinuation of the drug. Gabapentin combined with morphine achieved better analgesia at lower doses of each drug than each drug alone, with only mild adverse effects. The first medication that proved effective for neuropathic pain in placebo-controlled trials was TCAs. Treatment decisions for patients with neuropathic pain can be difficult. Interest in the mechanisms and treatment of chronic neuropathic pain has increased during the past years, resulting in significant treatment advances in the future. In this article all recent knowledge on therapeutic management of chronic neuropathic pain is presented.

Considerations in the management of bipolar disorder in women

OBJECTIVE

Recent research has emphasized important gender differences in the epidemiology, course, comorbidity and treatment of bipolar disorder. This article aims to provide an overview of these important findings in order to assist the clinician in treating women with bipolar disorder. Complex issues regarding the treatment of bipolar disorder during pregnancy and the post-partum period are discussed.

METHOD

A literature review was undertaken using Medline (1966-current), PsychInfo and PubMed databases. Search terms used were gender, sex, women, bipolar disorder, suicide, epidemiology, rapid cycling, mixed episode, treatment, mood stabilizers, antidepressants, antipsychotics, pregnancy, post-partum, menopause, lactation and breast-feeding.

RESULTS

The lifetime prevalence of bipolar I disorder is equal in men and women; however, bipolar II appears to be more common in women. Gender differences have been reported in the phenomenology, course and outcome of this condition. Some comorbid disorders, such as thyroid disease and anxiety disorders have more relevance to women. Increasingly, sex differences in the pharmacokinetics and pharmacodynamics of medications used in bipolar disorder are being reported.

CONCLUSIONS

There is increasing evidence for gender differences in a number of clinical features of bipolar disorder that have relevance to management. Although more studies are needed, it is important for clinicians to be aware of these issues to optimize treatment of women with this condition.

Lamotrigine for bipolar disorder: translating research into clinical practice

Lamotrigine (Lamictal, GlaxoSmithKline) is a recently developed anticonvulsant which has been investigated for efficacy in bipolar disorder. Increasing evidence indicates that it may have a different therapeutic profile than more established first-line mood stabilizers such as lithium and valproate. In particular, evidence from well-designed trials suggests efficacy for acute management and prophylaxis of bipolar depression but not mania. However, clinically relevant drug interactions and side effects can occur with lamotrigine, including benign to serious rash. The objectives of this drug profile are to review the basic chemical and pharmacological characteristics of lamotrigine, critically examine the growing body of research literature on its clinical use in the treatment of bipolar disorder, and review the safety and tolerability of lamotrigine as well as drug interactions relevant to clinical practice. Practical recommendations regarding titration and the management of rash are offered.

Carbonic anhydrase inhibitors: aromatic and heterocyclic sulfonamides incorporating adamantyl moieties with strong anticonvulsant activity

A series of aromatic/heterocyclic sulfonamides incorporating adamantyl moieties were prepared by reaction of aromatic/heterocyclic aminosulfonamides with the acyl chlorides derived from adamantyl-1-carboxylic acid and 1-adamantyl-acetic acid. Related derivatives were obtained from the above-mentioned aminosulfonamides with adamantyl isocyanate and adamantyl isothiocyanate, respectively. Some of these derivatives showed good inhibitory potency against two human CA isozymes involved in important physiological processes, CA I, and CA II, of the same order of magnitude as the clinically used drugs acetazolamide and methazolamide. The lipophilicity of the best CA inhibitors was determined and expressed as their experimental log k' IAM and theoretical ClogP value. Their lipophilicity was propitious with the crossing of the blood-brain barrier (log k' > IAM > 1.35). The anticonvulsant activity of some of the best CA inhibitors reported here has been evaluated in a MES test in mice. After intraperitoneal injection (30 mg kg(-1)), compounds A8 and A9 exhibited a high protection against electrically induced convulsions (> 90%). Their ED50 was 3.5 and 2.6 mg kg(-1), respectively.

Li+ enhances GABAergic inputs to granule cells in the rat hippocampal dentate gyrus

Defects in GABAergic interneurons are thought to be involved in the pathophysiology of bipolar disorder, and Li+ has been used as a primary therapeutic agent in the treatment. We used the patch clamp technique to investigate whether Li+ affects on spontaneous GABAergic synaptic inputs to granule cells (GCs) in hippocampal dentate gyrus. Extracellularly applied Li+ (25 mM) markedly increased the frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs), an effect completely blocked by picrotoxin or bicuculline. Li+ increased sIPSCs frequency in the presence of tetrodotoxin (TTX), but to a lesser extent than its absence. Li+ caused no change in the cumulative amplitude distribution of miniature IPSCs, indicating that a presynaptic mechanism is involved. When TTX was added in the presence of Li+, large-amplitude sIPSCs (>30 pA) were abolished specifically with no effect on small-amplitude sIPSCs (<20 pA). Intracellular Li+ (6 mM) applied via the patch pipette depolarized the resting membrane potential in fast-spiking interneurons, resulting in an increase in spontaneous action potential (AP) firing. This change, however, was not observed in GCs. These results suggest that Li(+)-induced spontaneous AP firing in GABAergic interneurons contributes to the increase in GABAergic synaptic inputs to GCs.

GABA-ergic drugs: exit stage left, enter stage right

Drugs that enhance gamma-aminobutyric acid (GABA) activity by interacting at post-synaptic GABA(A) receptors have long been used as hypnotics, sedatives, tranquillizers and anticonvulsants. In this category, benzodiazepines rapidly gained pride of place, replacing barbiturates and becoming the most commonly prescribed of all drugs in the Western world in the 1970s. However, problems such as dependence and withdrawal reactions became apparent in the 1980s, and it seemed that the usefulness of drugs with this mode of action was limited. Recently, focus has shifted to a new group of drugs with GABA-ergic actions mediated through various mechanisms not directly involving the GABA(A) receptor. These drugs include gabapentin, vigabatrin, tiagabine, lamotrigine, pregabalin and others. Although originally developed as anticonvulsants for epilepsy, they appear to have wider applications for use in affective disorders, especially bipolar depression, anxiety disorders and pain conditions. The current information on the properties and therapeutic potential of this new generation of GABA-ergic drugs is reviewed. It remains to be seen whether long-term use leads to tolerance, dependence and withdrawal or discontinuation reactions.

Gabapentin for the management of hot flushes: a case series

OBJECTIVE

To audit the effectiveness of the anticonvulsant gabapentin on hot flushes in postmenopausal women.

DESIGN

This was an open case series involving 11 postmenopausal women who were willing to take gabapentin for the relief of their hot flushes and were willing to keep a diary recording the number and intensity of their hot flushes, both before and during treatment. Gabapentin was started at a dose of 300 mg, to be taken at night, and the women were instructed to increase the dose up to 1,200 mg, according to symptom behavior.

RESULTS

Eleven women agreed to participate for on average 53.22 days (range, 2-79 days), but two discontinued participation-one before starting treatment and one after 2 days-so there are complete data sets for nine women. Gabapentin was found to be extremely effective in reducing hot flush activity (P < 0.001; Fig. 1). A significant reduction in symptoms was observed with a dose of 300 mg/day (P < 0.001). Scores on the Green Climacteric Scale were significantly improved from a mean of 25.72 (range, 12-42) to 19.25 (range, 13-31; P < 0.001). Palpitations (P = 0.001), panic attacks (P = 0.0001), mood (P = 0.023), muscle and joint pains (P = 0.021), and paresthesias and loss of sensation in the extremities (P = 0.001) were also shown to improve with treatment.

CONCLUSIONS

In the present case series, gabapentin was well tolerated and could be a valuable alternative for the treatment of hot flushes in women with contraindications to hormonal replacement therapy. It would be particularly beneficial for women in whom aches and pains and paresthesias are also a significant feature of the climacteric syndrome.

Bipolar depression: management options

Bipolar depression is the predominant abnormal mood state in bipolar disorder. However, despite the key pertinence of this phase of the condition, the focus of research and indeed of clinical interest in the management of bipolar disorder has been mainly on mania. Bipolar depression has been largely neglected, and early studies often failed to distinguish depression due to major unipolar depression from that due to bipolar disorder. Consequently, many treatments used in the management of major depression have been adopted for use in bipolar depression without any robust evidence of efficacy. The selective serotonin reuptake inhibitors (SSRIs), bupropion, tricyclic antidepressants and monoamine oxidase inhibitors are all effective antidepressants in the management of bipolar depression. They are all associated with a small risk of antidepressant-induced mood instability. The mood stabilisers lithium, carbamazepine and valproate semisodium (divalproex sodium) all appear to have modest acute antidepressant properties. Among these, lithium is supported by the strongest data, but the use of lithium in the treatment of bipolar depression as a monotherapeutic agent is limited by its slow onset of action. Recently, there has been a growing body of evidence suggesting that lamotrigine may have particular effectiveness in both the acute and prophylactic management of bipolar depression. Clinical management of bipolar depression involves various combinations of antidepressants and mood stabilisers and is partly determined by the context in which the depressive episode occurs. In general, 'de novo' and 'breakthrough' (where the patient is already receiving medication) bipolar depression may be successfully managed by initiating mood stabiliser monotherapy, to which an antidepressant or second mood stabiliser may be added at a later date, if necessary. Breakthrough episodes of bipolar depression occurring in patients receiving combination therapy (two mood stabilisers or a mood stabiliser plus an antidepressant) require either switching of ongoing medications or further augmentation. If this fails, then novel strategies or ECT should be considered. Bipolar depression is a disabling illness and the predominant mood state for the vast majority of those with bipolar disorder. It therefore warrants prompt management once suitably diagnosed, especially as it is associated with a considerable risk of suicide and in the majority of instances is eminently treatable.