An open label study of gabapentin in the treatment of acute mania

Gabapentin: Clinical Use and Pharmacokinetics in Dogs, Cats, and Horses

Gabapentin is an anticonvulsant drug, which presents an established clinical efficacy in human patients for the management of refractory partial seizures, secondarily generalized tonic-clonic seizures, and for the control of chronic neuropathic pain. Gabapentin was synthesized as a structural analogue of the inhibitory neurotransmitter GABA, with GABA-mimetic effects, able to cross the blood-brain barrier. In veterinary medicine, is extra-label used in combination with other treatments to control seizures when other drugs are no longer effective or become toxic or for neuropathic pain treatment and anxiety. This review aimed to clarify gabapentin use and pharmacokinetic aspects to promote conscious use in dogs, cats, and horses. In dogs, gabapentin was beneficial in the treatment of epilepsy, as well as chronic, neuropathic, and post-operative pain, as well as anxiety. In cats, it showed efficacy in post-ovariohysterectomy-related pain and in anxiety management. In horses, gabapentin has been administered as an analgesic for chronic pain management. In conclusion, when used in combination with other drugs, gabapentin can be considered an interesting therapeutic option for the treatment of neuropathic diseases and analgesia in postoperative and chronic pain. However, despite its beneficial use in different clinical settings, further trials and pharmacokinetic studies are needed for the definition of an effective dosage regimen through proper pharmacokinetic/pharmacodynamic correlation in dogs, cats, and horses.

A Systematic Review of the Clinical Use of Gabapentin and Pregabalin in Bipolar Disorder

Despite its prevalence and disease burden, several chasms still exist with regard to the pharmacotherapy of bipolar disorder (BD). Polypharmacy is commonly encountered as a significant proportion of patients remain symptomatic, and the management of the depressive phase of the illness is a particular challenge. Gabapentin and pregabalin have often been prescribed off-label in spite of a paucity of evidence and clinical practice guidelines to support its use. This systematic review aimed to synthesize the available human clinical trials and inform evidence-based pharmacological approaches to BD management. A total of six randomized, controlled trials (RCTs) and 13 open-label trials involving the use of gabapentin and pregabalin in BD patients were reviewed. Overall, the studies show that gabapentin and its related drug pregabalin do not have significant clinical efficacy as either monotherapy or adjunctive therapy for BD. Gabapentin and pregabalin are probably ineffective for acute mania based on the findings of RCT, with only small open-label trials to support its potential adjunctive role. However, its effects on the long-term outcomes of BD remain to be elucidated. The evidence base was significantly limited by the generally small sample sizes and the trials also had heterogeneous designs and generally high risk of bias.

Use of Gabapentin in the Treatment of Substance Use and Psychiatric Disorders: A Systematic Review

Objective: Gabapentin (GBP) is an anticonvulsant medication that is also used to treat restless legs syndrome (RLS) and posttherapeutic neuralgia. GBP is commonly prescribed off-label for psychiatric disorders despite the lack of strong evidence. However, there is growing evidence that GBP may be effective and clinically beneficial in both psychiatric disorders and substance use disorders. This review aimed to perform a systematic analysis of peer-reviewed published literature on the efficacy of GBP in the treatment of psychiatric disorders and substance use disorders. Methods: This review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The PubMed and Ovid MEDLINE literature databases were screened and filtered by using specific search terms and inclusion/exclusion criteria. The full texts of selected studies were subsequently retrieved and reviewed. The search terms generated 2,604 results from the databases. After excluding all duplicates, 1,088 citations were left. Thereafter, we applied inclusion and exclusion criteria; a total of 54 papers were retained for detailed review. Results: This literature review concludes that GBP appears to be effective in the treatment of various forms of anxiety disorders. It shows some effectiveness in bipolar disorder as an adjunctive therapeutic agent, while the evidence for monotherapy is inconclusive. In substance use disorders, GBP is effective for acute alcohol withdrawal syndrome (AWS) with mild to moderate severity; it reduces cravings, improves the rate of abstinence, and delays return to heavy drinking. GBP may have some therapeutic potential in the treatment of opioid addiction and cannabis dependence, but there is limited evidence to support its use. No significant benefit of GBP has been conclusively observed in the treatment of OCD, PTSD, depression, or cocaine and amphetamine abuse. Conclusion: GBP appears to be effective in some forms of anxiety disorders such as preoperative anxiety, anxiety in breast cancer survivors, and social phobia. GBP has shown to be safe and effective in the treatment of alcohol dependence. However, the literature suggests that GBP is effective as an adjunctive medication rather than a monotherapy. More clinical trials with larger patient populations are needed to support gabapentin's off-label use in psychiatric disorders and substance use disorders. It is worth noting that numerous clinical studies that are discussed in this review are open-label trials, which are inherently less rigorously analyzed. Therefore, more extensive investigations are required to examine not only the efficacy of GBP, but also its safety and tolerance.

Utilization of gabapentin by people in treatment for substance use disorders in Belgium (2011-2014): a cross-sectional study

Background

Although gabapentin has been licensed in the European Union only for neuropathic pain and epilepsy for patients who have partial seizures, it has also been prescribed in treatment for substance use disorders. Many studies report the potential risk of abuse of gabapentin by people with substance use disorders. The objective of this paper is to determine if people who have been in treatment for substance use disorders bought gabapentin in a time span that could indicate consumption at a dose that exceeded the maximum approved dose of 3600 mg/day.

Methods

This analysis is the result of an observational cross-sectional descriptive study with matching. Two datasets were used and linked at individual level. Subjects were selected based on their first registration in the database of the Treatment Demand Indicator (TDI) between 2011 and 2014, without any exclusion criteria concerning nationality or age. Through linkage with the database of the InterMutualistic Agency (IMA) information on health service use and medication use was determined. In addition, each subject was matched on age, sex and place of residence to four comparators from the general population who were not in specialized treatment. The prevalence of gabapentin purchases in the period between 2008 and 2014 for both populations were compared. Quantification of the amount of gabapentin between two consecutive purchases was used as a proxy for potential abuse.

Results

Out of 30,905 patients in treatment for substance use disorders 2.7% had bought at least once gabapentin in a public pharmacy or received it from a hospital pharmacy, compared to 0.7% in the comparison group (n = 122,142). In both populations, more than half of the patients bought only once or twice gabapentin and about 10.0% bought at least once gabapentin in a time span that could indicate potential abuse. A limitation of the study is that it is only based on reimbursed medication without clinical information.

Conclusion

Through the linkage of the TDI-database and the database of the Belgian health insurance companies, no evidence was found for regular abuse of prescribed gabapentin in Belgium by people in treatment for substance use disorders.

HCN Channel Targets for Novel Antidepressant Treatment

Major depressive disorder (MDD) is a chronic and potentially life threatening illness that carries a staggering global burden. Characterized by depressed mood, MDD is often difficult to diagnose and treat owing to heterogeneity of syndrome and complex etiology. Contemporary antidepressant treatments are based on improved monoamine-based formulations from serendipitous discoveries made > 60 years ago. Novel antidepressant treatments are necessary, as roughly half of patients using available antidepressants do not see long-term remission of depressive symptoms. Current development of treatment options focuses on generating efficacious antidepressants, identifying depression-related neural substrates, and better understanding the pathophysiological mechanisms of depression. Recent insight into the brain's mesocorticolimbic circuitry from animal models of depression underscores the importance of ionic mechanisms in neuronal homeostasis and dysregulation, and substantial evidence highlights a potential role for ion channels in mediating depression-related excitability changes. In particular, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are essential regulators of neuronal excitability. In this review, we describe seminal research on HCN channels in the prefrontal cortex and hippocampus in stress and depression-related behaviors, and highlight substantial evidence within the ventral tegmental area supporting the development of novel therapeutics targeting HCN channels in MDD. We argue that methods targeting the activity of reward-related brain areas have significant potential as superior treatments for depression.

Emerging Treatments for Bipolar Disorder: Safety and Adverse Effect Profiles

Objective:

To provide an overview of the safety and tolerability of newer agents used to treat bipolar disorder (BPD) and provide clinicians with management strategies for drug-related toxicity and adverse effects.

Data Sources:

MEDLINE was searched through July 2005 for BPD treatment, adverse effects, tolerability, safety, emerging agents, atypical antipsychotics, new antiepileptic drugs (AEDs), risperidone, quetiapine, clozapine, ziprasidone, aripiprazole, lamotrigine, topiramate, gabapentin, oxcarbazepine, and olanzapine.

Study Selection and Data Extraction:

Results from randomized controlled trials, open-label studies, and reviews are described.

Data Synthesis:

Emerging agents recently approved for BPD include atypical antipsychotics and new AEDs. Safety and tolerability are as Important as efficacy because poor adherence in BPD worsens outcome; metabolic and other comorbidities pose specific challenges; and manic patients often require combination therapy, which increases adverse effects. Most atypical antipsychotics cause fewer extrapyramidal symptoms than conventional antipsychotics, but may cause more weight gain and metabolic complications. The newer AEDs generally cause less weight gain than the older agents, and some even promote weight loss. Several newer AEDs used in BPD also offer the advantages of fewer drug interactions and less need for therapeutic drug monitoring compared with older AEDs.

Conclusions:

Pending the results of ongoing controlled studies, several emerging agents may be useful additions to the therapeutic arsenal for BPD.

Involvement of NO/cGMP pathway in the antidepressant-like effect of gabapentin in mouse forced swimming test

Based on clinical studies regarding the beneficial effect of gabapentin in depression, we aimed to evaluate the antidepressant-like properties of gabapentin in mice and also the participation of nitric oxide (NO)/cyclic guanosine monophosphate pathway in this effect. The following drugs were used in this study: gabapentin; N(G)-nitro-L-arginine methyl ester (L-NAME), a non-specific NO synthase (NOS) inhibitor; 7-nitroindazole, a specific neuronal NOS inhibitor; aminoguanidine, a specific inducible NOS inhibitor; L-arginine, a NO precursor; and sildenafil, a phosphodiestrase inhibitor. Finally, we studied the behavioral effects through the forced swimming test (FST) and the changes of the hippocampus NO level through nitrite assay. The immobility time was significantly reduced after gabapentin administration. Co-administration of non-effective doses of gabapentin and L-NAME or 7-nitroindazole (7-NI) resulted in antidepressant-like effect in FST, while aminoguanidine did not affect the immobility time of gabapentin-treated mice. Furthermore, the antidepressant-like property of gabapentin was prevented by L-arginine or sildenafil. Also, the hippocampal nitrite level was significantly lower in gabapentin-treated mice relative to saline-injected mice, and co-administration of 7-NI with sub-effective gabapentin caused a significant decrease in hippocampal nitrite levels. Our results indicate that the antidepressant-like effect of gabapentin in the mice FST model is mediated at least in part through nitric oxide/cyclic guanosine monophosphate (cGMP) pathway.

Gabapentin Therapy in Psychiatric Disorders: A Systematic Review

OBJECTIVE

Gabapentin is commonly used off-label in the treatment of psychiatric disorders with success, failure, and controversy. A systematic review of the literature was performed to elucidate the evidence for clinical benefit of gabapentin in psychiatric disorders.

DATA SOURCES

Bibliographic reference searches for gabapentin use in psychiatric disorders were performed in PubMed and Ovid MEDLINE search engines with no language restrictions from January 1, 1983, to October 1, 2014, excluding nonhuman studies. For psychiatric references, the keywords bipolar, depression, anxiety, mood, posttraumatic stress disorder (posttraumatic stress disorder and PTSD), obsessive-compulsive disorder (obsessive-compulsive disorder and OCD), alcohol (abuse, dependence, withdraw), drug (abuse, dependence, withdraw), opioid (abuse, dependence, withdraw), cocaine (abuse, dependence, withdraw), and amphetamine (abuse, dependence, withdraw) were crossed with gabapentin OR neurontin.

STUDY SELECTION AND DATA EXTRACTION

The resulting 988 abstracts were read by 2 reviewers; references were excluded if gabapentin was not a study compound or psychiatric symptoms were not studied. The resulting references were subsequently read, reviewed, and analyzed; 219 pertinent to gabapentin use in psychiatric disorders were retained. Only 34 clinical trials investigating psychiatric disorders contained quality of evidence level II-2 or higher.

RESULTS

Gabapentin may have benefit for some anxiety disorders, although there are no studies for generalized anxiety disorder. Gabapentin has less likely benefit adjunctively for bipolar disorder. Gabapentin has clearer efficacy for alcohol craving and withdrawal symptoms and may have a role in adjunctive treatment of opioid dependence. There is no clear evidence for gabapentin therapy in depression, PTSD prevention, OCD, or other types of substance abuse. Limitations of available data include variation in dosing between studies, gabapentin as monotherapy or adjunctive treatment, and differing primary outcomes between trials.

CONCLUSIONS

Further research is required to better clarify the benefit of gabapentin in psychiatric disorders.

Anticonvulsant drugs in bipolar disorder

Although much progress has been made in successfully treating bipolar disorder, there is increasing awareness of the limitations of traditional treatment regimens such as lithium and neuroleptics. The large family of anticonvulsant drugs, however, appears to be capable of providing new treatment options, not only as medication of second choice in patients refractory to treatment, but often as a treatment standard with high efficacy and low incidence of side effects. Besides established mood stabilizers such as carbamazepine and valproate, new antiepileptic drugs are entering the field with promising initial results in the treatment of bipolar patients. Furthermore, bringing to light the mechanisms of action of anticonvulsants and the similarities between anticonvulsants effective in bipolar disorder may also deepen our understanding of the pathophysiological basis of the disorder.

Newer Anticonvulsant Drugs in Neuropathic Pain and Bipolar Disorder

Older anticonvulsants have been used to manage both chronic pain and bipolar disorders. As the armamentarium of anticonvulsants increases, the role of the newer agents for pain or mood disorders is uncertain. This paper summarizes the clinical data available with gabapentin, lamotrigine, oxcarbazepine, tiagabine and topiramate for bipolar disorder and lamotrigine, oxcarbazepine, tiagabine and topiramate for neuropathic pain.

Gabapentin in the treatment of mental illness: the echo chamber of the case series

BACKGROUND

Bipolar disorder is a common and debilitating psychiatric illness. Several antiepileptic drugs (AEDs) have been approved for the treatment of bipolar disorder. Gabapentin gained a large market share of AED use in the late 1990s in spite of a lack of randomized clinical trial (RCT) evidence and no labeled indication from the U.S. Food and Drug Administration for its use in psychiatric illness. This article describes the results of a literature review, the purpose of which was to examine the characteristics of studies conducted in humans concerning the efficacy of gabapentin in bipolar disorder.

METHODS

Publications relevant to this topic were identified based on a PUBMED search as well as an examination of references from a published systematic review and citations from relevant review articles.

RESULTS

The search located 29 studies published between 1997 and 2007, with the greatest number of articles published in 1998 and 1999. Of these 29 publications, 15 involved uncontrolled case series, while 6 were single case reports. The sample size in the studies was generally small, and often we could not identify the funding source. Despite the generally weak study design in the identified publications, the authors of the articles often commented on the promising nature of gabapentin therapy for bipolar disorder. However, 4 small, randomized trials in heterogeneous populations demonstrated little if any evidence of such efficacy. Nine letters to the editor demonstrated a similar pattern.

CONCLUSIONS

The large number of case series concerning gabapentin is striking. The number of reports and their distribution in many different journals created a type of "echo chamber" effect, through which the sheer number of publications and citations may give legitimacy to the practice of using gabapentin for bipolar disorder. Although the case series were generally of poor quality, their publication in peer-reviewed journals may have been partially responsible for the widespread use of an ineffective medication.

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.

Psychopharmacology of pediatric bipolar disorder: a review

RATIONALE

Pediatric bipolar disorder (PBD) is a chronic and debilitating psychiatric illness. It is associated with many short-term and long-term complications including poor academic and social performance, legal problems and increased risk of suicide. Moreover, it is often complicated by other serious psychiatric disorders including attention deficit hyperactivity disorder, oppositional defiant disorder, conduct disorder and substance use disorders. For these reasons, there is a need for effective treatment for PBD.

OBJECTIVES

To review available data from published reports of the treatment of PBD, highlighting those treatment practices for which there is scientific evidence. To suggest directions for future research.

MATERIALS AND METHODS

A comprehensive Medline search was performed to identify published reports from 1995 to 2006. Reports with the greatest methodological stringency received greater focus.

RESULTS

There is limited evidence from double-blind, placebo-controlled trials regarding the treatment of PBD. Available data suggests that lithium, some anticonvulsants and second-generation antipsychotics may be equally beneficial in the acute monotherapy for youth with mixed or manic states. However, because of limited response to acute monotherapy, there is increased justification for combination therapy. There is very limited data on the treatment of the depressed phase of bipolar illness in the youth. Also, very few studies have addressed the treatment of comorbidities and maintenance/relapse prevention in PBD.

CONCLUSION

Although significant progress was made in the treatment of youth with bipolar disorder, there is a need for more methodologically stringent research to more precisely define evidence-based treatment strategies for PBD.

Safety and tolerability of emerging pharmacological treatments for bipolar disorder

OBJECTIVES

Over the past few years numerous new agents have been examined for their efficacy in bipolar disorder (BPD). New antiepileptic agents and atypical antipsychotics currently form the bulk of these emerging agents. As the armamentarium for treating BPD increases, it allows for the possibility of choosing drugs on the basis of their tolerability as well as their efficacy, rather than on efficacy alone.

METHODS

Efficacy data for newer antiepileptic drugs (lamotrigine, topiramate, gabapentin, oxcarbazepine) and atypical antipsychotics (olanzapine, clozapine, risperidone, quetiapine, ziprasidone, aripiprazole) are briefly reviewed. The article focuses on relative safety and tolerability of these agents.

RESULTS

In general, most of these newer agents have better side effect and tolerability profiles than older agents commonly used to treat BPD (lithium, valproate, carbamazepine); however, these must be weighed against efficacy demonstrated to date in randomized, controlled trials. Cognitive impairment is a concern with topiramate, weight gain and risk of diabetes with some of the atypical antipsychotic agents, and rash with lamotrigine.

CONCLUSIONS

Side effects of newer emerging agents for the treatment of BPD can be effectively managed and the risks reduced by instituting practical strategies early in management.

Recent developments in the treatment of bipolar disorders

Recently, many new therapeutic options have become available for the treatment of bipolar disorder. Most of these options are agents originally developed to treat other conditions, such as anticonvulsants and antipsychotics. Some older agents have also been rediscovered or reformulated. New drug combinations and treatment strategies have enabled a more comprehensive treatment of the spectrum of bipolar symptoms, as well as bipolar disorder complicated by a range of comorbidities, to be targeted. A growing range of novel therapeutic options for the treatment of bipolar disorder is under investigation. This paper summarises some of the data regarding these potential therapeutic options.

Treatment guidelines for children and adolescents with bipolar disorder

Clinicians who treat children and adolescents with bipolar disorder desperately need current treatment guidelines. These guidelines were developed by expert consensus and a review of the extant literature about the diagnosis and treatment of pediatric bipolar disorders. The four sections of these guidelines include diagnosis, comorbidity, acute treatment, and maintenance treatment. These guidelines are not intended to serve as an absolute standard of medical or psychological care but rather to serve as clinically useful guidelines for evaluation and treatment that can be used in the care of children and adolescents with bipolar disorder. These guidelines are subject to change as our evidence base increases and practice patterns evolve.

Treatment of acute mania

Mood stabilizers have evolved considerably over the past decade. Lithium, divalproex, and olanzapine are currently Food and Drug Administration-approved for the treatment of acute mania. A number of new and traditional medications have also been tested and are commonly used in clinical practice. Several strategies for managing treatment-resistant mania have been suggested, but few have been rigorously tested. Emphases on rapid stabilization and fewer side effects have raised the bar for what is expected from mood stabilizers and the successful treatment of mania involves a delicate balance between swiftness, short-term tolerability, and long-term safety.

The clinical use of gabapentin in bipolar spectrum disorders

BACKGROUND

with increasing awareness of lithium's limitations, several new anticonvulsants had been tested for their mood stabilisation during recent years. Among the innovative third generation mood stabilizing anticonvulsants, gabapentin (GBP) seems to have a broad spectrum of efficacy, although no certain data are available as to its efficacy and use in clinical practice. Accordingly, an extensive review on this subject has been carried out.

METHODS

A computer-generated search of the biomedical literature and abstract books of the more important scientific psychiatric congresses until June 2000 was undertaken to identify all pertinent case reports, case series and studies of GBP as monotherapy or adjunctive therapy in mood disorders. We identified 40 open-label studies on the use of GBP in at least 600 patients with bipolar disorder (BP), manic, depressed, or mixed episodes and unipolar depression and four controlled studies.

RESULTS

The 40 open-label studies and two of the controlled trials suggested that GBP may have a role as adjunctive agent in the treatment of patients with bipolar disorders particularly when complicated by co-morbid anxiety disorder or substance abuse. GBP is usually very well tolerated and has no pharmacological interference with other mood stabilisers. However, in the other two double-blind studies GBP has not been found to be efficacious in the treatment of refractory mania or refractory bipolar depression.

CONCLUSIONS

Although failing to show clear antimanic efficacy in randomized trials, gabapentin still remains a clinically useful agent when it comes to combination treatment in refractory and co-morbid patients.

Effects of gabapentin on anxiety induced by simulated public speaking

The effects of gabapentin, 400 mg and 800 mg, on anxiety induced by simulated public speaking (SPS) were investigated. Thirty-two normal male volunteers (aged 17-30 years) had their anxiety and mood evaluated by self-scales [Visual Analogue Mood Scale (VAMS) and Profile of Mood State (POMS)] during the SPS procedure. Physiological measures (heart rate and blood pressure) were taken. Treatment with gabapentin at 800 mg attenuated the anxiety of subjects that had a decrease on the VAMS item calm-excite. In addition, volunteers that received gabapentin at 400 mg and 800 mg showed a decrease in the hostility score in POMS. Our results suggest, in agreement with other studies, an anxiolytic potential to gabapentin.

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.

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

The so-called atypical forms of bipolar disorder are not a rarity, but instead are rather the rule. Particularly in specialized settings such as the bipolar disorder clinic, the majority of patients are characterized by atypical manifestations (). Mixed states, psychotic mania and a rapid cycling course of bipolar disorder are a challenge both to pharmacological and non-pharmacological treatment. The benefit of classical mood stabilizers such as lithium and carbamazepine is limited in monotherapy, although valproate has a broader spectrum of activity in atypical bipolar disorders and is often used in combination with other agents. Thus, new treatment alternatives are needed urgently for optimizing the treatment of atypical bipolar disorder. During the last decade, several new antiepileptic drugs have been released, e.g. lamotrigine, gabapentin, tiagabine, topiramate and levetiracetam. Others have been available for some time, but only recently have become the focus of bipolar disorder research; for example, phenytoin, and especially, oxcarbazepine. This review will consider our current knowledge of the benefit of these new and newly rediscovered anticonvulsants in treating bipolar disorders, with a special focus on their value in treating atypical manifestations.

Effectiveness of adjunctive gabapentin in resistant bipolar disorder: is it due to anxious-alcohol abuse comorbidity?

We evaluated effectiveness and predictors of response of gabapentin (GBP) as adjunctive treatment in a sample of 43 subjects with DSM-III-R bipolar disorder who were resistant to standard mood stabilizers. Diagnostic evaluation was performed by means of the Semistructured Interview for Mood Disorder. Clinical evaluation was performed at the beginning and end of the observation period by means of the Hamilton Rating Scale for Depression (HAM-D), the Young Mania Rating Scale, and the Clinical Global Impression Scale. GBP was administered as an adjunctive treatment for an 8-week period in combination with other mood stabilizers, benzodiazepines, antidepressants, and neuroleptics. Mean dosage +/- SD at week 8 was 1270 +/- 561.4 mg (range, 600-2400 mg). Adjunctive treatment with GBP was well tolerated by almost all the subjects; only three patients had to interrupt treatment before week 8, two because of inefficacy and one because of the appearance of side effects (ataxia and irritability); in other patients, the most frequent side effects were sedation, irritability, tremor, ataxia or motor instability, and nausea. Eighteen (41.9%) of 43 patients who began treatment were considered responders. Mean total HAM-D score showed a significant reduction during the 8 weeks of treatment. Analysis of the various HAM-D dimensions showed that the anxiety-somatization factor was the one with the greatest change. Seventeen of the 18 responder patients remained in remission for a period ranging from 4 to 12 months without clinically significant side effects or adverse events. One patient had to interrupt GBP treatment and be administered neuroleptics because of the reappearance of manic symptoms. Regarding response predictors, logistical regression analysis showed that the presence of panic disorder and alcohol abuse was associated with positive response. The results of the present study replicate prior studies indicating that GBP is an effective and well tolerated treatment in a large proportion of bipolar patients who are resistant to traditional mood stabilizers. More specifically, this drug appears to have antidepressant and anxiolytic properties. What is new in the present report is the suggestion that the utility of GBP in resistant bipolar disorder resides in its effectiveness against comorbid panic disorder and alcohol abuse.

The Bech-Rafaelsen Mania Scale in clinical trials of therapies for bipolar disorder: a 20-year review of its use as an outcome measure

Over the last two decades the Bech-Rafaelsen Mania Scale (MAS) has been used extensively in trials that have assessed the efficacy of treatments for bipolar disorder. The extent of its use makes it possible to evaluate the psychometric properties of the scale according to the principles of internal validity, reliability, and external validity. Studies of the internal validity of the MAS have demonstrated that the simple sum of the 11 items of the scale is a sufficient statistic for the assessment of the severity of manic states. Both factor analysis and latent structure analysis (the Rasch analysis) have been used to demonstrate this. The total score of the MAS has been standardised such that scores below 15 indicate hypomania, scores around 20 indicate moderate mania, and scores around 28 indicate severe mania. The inter-observer reliability has been found to be high in a number of studies conducted in various countries. The MAS has shown an acceptable external validity, in terms of both sensitivity and responsiveness. Thus, the MAS was found to be superior to the Clinical Global Impression scale with regard to responsiveness, and sensitivity has been found to be adequate, with the MAS able to demonstrate large drug-placebo differences. Based on pretreatment scores, trials of antimanic therapies can be classified into: (i) ultrashort (1 week) therapy of severe mania; (ii) short-term therapy (3 to 8 weeks) of moderate mania; (iii) short-term therapy of hypomanic or mixed bipolar states; and (iv) long-term (12 months) therapy of bipolar states. The responsiveness of MAS is such that the scale has been able to demonstrated that typical antipsychotics are effective as an ultrashort therapy of severe mania; that lithium and anticonvulsants are effective in the short-term therapy of moderate mania; and that atypical antipsychotics, electroconvulsive therapy (ECT) and transcranial magnetic stimulation seem to have promising effects in the short-term therapy of moderate mania. In contrast, the scale has been used to demonstrate that calcium antagonists (e.g. verapamil) are ineffective in the treatment of mania. MAS has also been used to add to the literature on the evidence-based effect of lithium as a short-term therapy for hypomania or mixed bipolar states and as a long-term therapy of bipolar states.

Clinical predictors of response to lamotrigine and gabapentin monotherapy in refractory affective disorders

BACKGROUND

The objective of the current study was to examine possible clinical predictors of positive response to lamotrigine or gabapentin monotherapy in treatment-refractory affectively ill patients.

METHODS

Forty-five patients with treatment refractory bipolar (n = 35) or unipolar (n = 10) affective disorder participated in a clinical study evaluating six weeks of treatment with lamotrigine, gabapentin, or placebo monotherapy given in a double-blind, randomized fashion with two subsequent cross-overs to the other agents. Patients received daily mood ratings and weekly cross-sectional scales. Much or very much improved on the Clinical Global Impression scale modified for bipolar illness was considered a positive response. Degree of response was correlated with a number of baseline demographic and course of illness variables in a univariate analysis and then by linear regression.

RESULTS

Response rates to lamotrigine (51%) exceeded those to gabapentin (28%) and placebo (21%). A positive response to lamotrigine monotherapy was associated with a bipolar diagnosis; fewer hospitalizations; fewer prior medication trials; and male gender (of which the latter two variables survived logistic regression). For gabapentin, degree of response correlated with shorter duration of illness; younger age; and lower baseline weight (with the latter two surviving linear regression).

CONCLUSIONS

In this highly treatment-refractory population, lamotrigine appeared most effective for male patients with fewer prior medication trials. Gabapentin monotherapy, although not better than placebo, appeared most effective in those with younger age and lower baseline weight. These preliminary data in a treatment refractory subgroup may help in the further definition of the range of clinical utility of these widely used anticonvulsants.

Emerging options in the treatment of bipolar disorders

Bipolar disorder is a common and severe condition, and has a clinical outcome that is frequently sub-optimal. Only a small number of therapeutic options are currently available for the disorder. A growing range of novel therapeutic options for the treatment of bipolar disorder are under investigation. These include the anticonvulsants, atypical antipsychotics and options such as the omega-3 fatty acids and transcranial magnetic stimulation. Of the anticonvulsants, lamotrigine is currently the agent for which the greatest amount of controlled clinical data is accumulating, particularly in the depressed and rapid cycling phases of the illness. Olanzapine is currently the atypical antipsychotic with the largest body of evidence in mania, although data is emerging on other atypical antipsychotics including risperidone and ziprasidone. Data regarding the atypical agents in other phases of the illness are awaited. The options available for this difficult to treat condition is increasing with the new range of agents.

Behavioural effects of the new anticonvulsants

Of the 9 new anticonvulsants that have been marketed recently in the UK or US, a number appear to have either adverse or beneficial effects on behaviour. There is now a considerable database of information, in terms of the number of patients treated and/or the number of published reports, on vigabatrin, lamotrigine, gabapentin and topiramate. Oxcarbazepine has been available in some centres for several years and there is extensive experience with the drug in Scandinavia. It appears that the profile of adverse and beneficial effects is similar to that of carbamazepine. Behavioural effects have probably been greatest with vigabatrin, with psychosis, depression and other behavioural problems recorded, but the use of this drug has been limited because of the concern about visual field constriction. The cognitive and behavioural effects of topiramate have caused concern, but these may be much less of a problem if lower starting dosages and escalation rates are used. Psychosis and depression have been associated with topiramate, as they have with another carbonic anhydrase inhibiting drug, zonisamide. Although zonisamide has been used for many years in Japan and Korea, experience elsewhere with this drug is currently very limited. Gabapentin seems to be less associated with adverse behavioural effects than some of the other new anticonvulsant drugs. The reports of behavioural disturbance with gabapentin in children may be related to dose escalation. Behavioural disturbance as a direct result of lamotrigine seems to be uncommon, although indirect effects on behaviour, through the so-called 'release phenomenon' from improved seizure control and consequent ability to misbehave, can occur. Positive behavioural effects have been described with several of the new anticonvulsants, particularly gabapentin, lamotrigine and oxcarbazepine; all of these drugs may have mood-levelling effects that could be of value in treating affective disorders. The information on tiagabine and levetiracetam is too limited to allow any firm conclusions to be drawn with regard to positive or negative behavioural effects. When interpreting reports of behavioural changes with anticonvulsants, it is important to avoid attributing the effect to the drug when one or more of the other multiple causes of behavioural disturbance in people with epilepsy may be responsible or when an indirect effect such as 'forced normalisation' may be the cause. Many of the published studies are retrospective and unblinded rather than double-blind, placebo-controlled, prospective trials, implying that much of the data must be interpreted with caution at this stage.

Treatment of alcohol withdrawal with gabapentin

Gabapentin is an anticonvulsant agent, also effective in the treatment of mood disorders and anxiety disorders. Three cases of alcohol withdrawal treated with gabapentin are presented. All patients received gabapentin 400 mg tid for 3 days, 400 mg bid for 1 day, and finally 400 mg for 1 day. Withdrawal symptoms subsided and no adverse effects were observed. The possible effectiveness of gabapentin in the treatment of alcohol withdrawal warrants further investigation by systematic and well-designed studies.

Gabapentin treatment for bipolar disorders

OBJECTIVE

[corrected] To review the effectiveness data on the use of gabapentin in bipolar disorders.

DATA SOURCES

Clinical literature was accessed through MEDLINE (January 1985-November 2000). Key search terms included gabapentin, mood stabilizer, and bipolar disorder.

DATA SYNTHESIS

Bipolar disorder is a complex condition that can be difficult to treat effectively. Mood stabilizers are increasingly being used to manage bipolar disorder. Studies that used gabapentin in bipolar disorders are evaluated.

CONCLUSIONS

From the data presented, gabapentin cannot be recommended for treatment of bipolar disorder. Further studies are required to determine whether gabapentin has any role in the management of bipolar disorder.

Bipolar disorders: new approaches to therapy

This article reviews the evidence supporting different somatic treatment strategies in the acute and maintenance treatment phases of bipolar disorder. Bipolar affective disorder is a chronic disorder with a life time incidence of 0.3 - 1.5/100 [1]. Severe affective disorder is associated with a risk of completed suicide of 6 - 15% [2,3]. Traditionally, bipolar disorder has been considered as an episodic disorder with good inter-episode recovery [4]. This is being increasingly challenged with patients demonstrating social, marital, occupational and cognitive dysfunction, even when euthymic [5]. The management of bipolar disorder should be considered in the context of; the type of episode, this may be manic, depressed or mixed; the degree and rate of recovery; the cycling frequency and precipitant, if any, for recurrence and the onset and evolution of the underlying illness. On average, four episodes occur every 10 years. However 13 - 24% of patients develop rapid cycling disorder, in which four or more episodes occur within a year. Patients with bipolar disorder often have co-morbid anxiety and substance abuse. Moreover, axis I co-morbidity may be associated with an earlier age at onset and worsening course of bipolar illness. [6]. Axis II co-morbidity is also common, this was highlighted in a study by Kay and colleagues who, after excluding patients with a history of alcohol misuse, demonstrated axis II co-morbidity in almost a quarter of euthymic bipolar patients [7]. Good practice relies on an overall management plan that incorporates somatic, psychological and social approaches. This paper will focus on one element of such a plan, the currently available somatic management strategies for bipolar disorder.

Adjunctive gabapentin in treatment-resistant depression: a retrospective chart review

BACKGROUND

Previous studies in predominantly bipolar patients have suggested that gabapentin may be useful in treating mood disorders. This report describes its efficacy and tolerability as an adjunctive agent in treatment-resistant depression.

METHODS

A chart review was conducted on 27 outpatients presenting with a depressive disorder in whom gabapentin was added to ongoing treatment with a conventional antidepressant to which patients had not responded after at least 6 weeks. The majority of patients had either prominent anxiety or a history of soft bipolar features, but patients with bipolar I disorder were excluded. Clinical state and adverse effects were assessed retrospectively at each visit.

RESULTS

Mean gabapentin trial duration was 15.2+/-7.8 weeks, with a mean final dose of 904+/-445 mg/day (range, 300-1800 mg/day). Clinician-rated measures of clinical state improved significantly from baseline to endpoint. Overall, 37.0% (n=10) of patients were responders at endpoint; another 18.5% (n=5) manifested a transient response not sustained to endpoint. Gabapentin was well tolerated; the most common adverse effects were fatigue, sedation, dizziness, and gastrointestinal symptoms.

LIMITATIONS

Treatment was uncontrolled and efficacy assessments were retrospective.

CONCLUSION

These findings suggest that gabapentin may be of adjunctive benefit in the management of treatment-resistant depression.

Developments in mood stabilisers

Bipolar affective disorder is a life-long condition with profound effects on sufferers' social and occupational life. Despite efficacy in clinical trials and in some groups of patients, lithium's effectiveness in clinical practice is hampered by its side effect profile and limited concordance. Alternative and adjunctive treatments to lithium in bipolar disorder have been sought and the anticonvulsants carbamazepine and valproate show promise. Despite these advances, treatment resistance persists. Lamotrigine, a new anticonvulsant, is increasingly used in treatment-resistant cases under specialist supervision. Further pharmacological and non-pharmacological strategies for bipolar prophylaxis are currently under investigation. These developments are the focus of this review.

A placebo-controlled study of lamotrigine and gabapentin monotherapy in refractory mood disorders

There is a pressing need for additional treatment options for refractory mood disorders. This controlled comparative study evaluated the efficacy of lamotrigine (LTG) and gabapentin (GBP) monotherapy versus placebo (PLC). Thirty-one patients with refractory bipolar and unipolar mood disorders participated in a double-blind, randomized, crossover series of three 6-week monotherapy evaluations including LTG, GBP, and PLC. There was a standardized blinded titration to assess clinical efficacy or to determine the maximum tolerated daily dose (LTG 500 mg or GBP 4,800 mg). The primary outcome measure was the Clinical Global Impressions Scale (CGI) for Bipolar Illness as supplemented by other standard rating instruments. The mean doses at week 6 were 274 +/- 128 mg for LTG and 3,987 +/- 856 mg for GBP. Response rates (CGI ratings of much or very much improved) were the following: LTG, 52% (16/31); GBP, 26% (8/31); and PLC, 23% (7/31) (Cochran's Q = 6.952, df = 2, N = 31, p = 0.031). Post hoc Q differences (df = 1, N = 31) were the following: LTG versus GBP (Qdiff = 5.33, p = 0.011); LTG versus PLC (Qdiff = 4.76, p = 0.022); and GBP versus PLC (Qdiff = 0.08, p = 0.70). With respect to anticonvulsant dose and gender, there was no difference between the responders and the nonresponders. The agents were generally well tolerated. This controlled investigation preliminarily suggests the efficacy of LTG in treatment-refractory affectively ill patients. Further definition of responsive subtypes and the role of these medications in the treatment of mood disorders requires additional study.

Adjunctive gabapentin treatment of bipolar disorder

INTRODUCTION

The aim of this study was to analyze the effectiveness of gabapentin administration to bipolar patients who had an incomplete response to other mood stabilizers.

SUBJECTS AND METHODS

Twenty-two RDC bipolar 1 and II patients were assessed by means of the SADS and entered if they gave their consent to participate. All them had suffered from frequent relapses, subsyndromal features (mostly depressive) and incomplete response to other drugs. They all received open-label increasing doses of gabapentin until clinical response. The patients were assessed through the CGI-BP and a specific questionnaire at baseline and at 12 weeks of follow-up.

RESULTS

Six out of the 22 patients dropped out for various reasons (four because of relapse, one because of side effects and one more because of poor compliance). Eight of the 16 patients that completed the 12-week follow-up showed at least two stages of improvement in the CGI. Using the last observation-carried forward analysis, the improvement was statistically significant for the depression subscale, and apparently related to social functioning, irritability and anxiety. Only one patient dropped out because of intolerance (mild rash). The mean dose of gabapentin was 1,310 mg/day.

CONCLUSION

Gabapentin may be a useful drug for the add-on treatment of bipolar patients with poor response to other mood stabilizers. Gabapentin may improve depressive residual symptoms such as irritability, social withdrawal or anxiety. These results should be confirmed in randomized clinical trials.

Gabapentin in bipolar disorder: a placebo-controlled trial of adjunctive therapy. Gabapentin Bipolar Disorder Study Group

OBJECTIVES

[corrected] To assess efficacy and safety of gabapentin in the treatment of bipolar disorder.

METHODS

This was a double-blind, placebo-controlled trial of adjunctive gabapentin (dosed flexibly between 900 and 3,600 mg/day). Patients with a lifetime diagnosis of bipolar disorder (type I), and who were currently suffering from symptoms of either mania, hypomania or a mixed state despite ongoing therapy with lithium, valproate, or lithium and valproate in combination were eligible for inclusion. The primary efficacy measures were the baseline to endpoint change in total score on the Young Mania Rating Scale (YMRS) and the Hamilton Depression Rating Scale (HAM-D).

RESULTS

Both treatment groups had a decrease in total YMRS from baseline to endpoint, but this decrease was significantly greater in the placebo group (-9) than the gabapentin group (-6) (p < 0.05). No difference between treatments was found for the total score on the HAM-D. Secondary efficacy measures were not different between treatment groups. More patients in the placebo group had changes made to their ongoing lithium therapy (n = 12) compared to the gabapentin group (n = 4). When these patients are removed from the efficacy analysis, the YMRS treatment difference still favors placebo, but is no longer statistically significant. Based on gabapentin plasma levels at termination, some patients did not take the study drug as prescribed.

CONCLUSIONS

The findings of this study did not demonstrate that gabapentin is an effective adjunctive treatment when administered to outpatients with bipolar disorder.

Anorgasmia in a patient with bipolar disorder type 1 treated with gabapentin

Gabapentin is a relatively new anticonvulsant indicated for adjunctive therapy in the treatment of partial seizures, with and without secondary generalization, in adults with epilepsy. Overall, it has a minimal side effect profile compared with other anticonvulsant agents. Postmarketing surveillance is needed to further delineate the spectrum of adverse events that may be experienced by patients treated with this medication. This is a case report of a 25-year-old man with a 10-year history of mood swings that progressively worsened and resulted in a suicide attempt 8 months before his first appointment. A diagnosis of bipolar disorder was established, and a clinical interview ruled out other mental disorders. The patient was administered gabapentin 300 mg/day, and the dose was titrated upward to 900 mg/day. A follow-up appointment revealed improved control of his bipolar symptoms. However, the patient reported that he could not have an orgasm during sexual intercourse. The medication was changed to valproic acid 250 mg three times daily. His bipolar symptoms remained under control and the anorgasmia resolved. This was maintained at the next follow-up appointment. The side effect profile and therapeutic monitoring requirements of gabapentin are favorable when compared with those of other anticonvulsant agents. However, because this agent is relatively new, especially for use in the treatment of bipolar disorder, a more thorough development of its side effect profile is needed. Observing, recording, and reporting atypical adverse events and side effects are critical to postmarketing surveillance and enhance the clinician's ability to make rational therapeutic decisions.

Serotonin in mania and in the mechanism of action of mood stabilizers: a review of clinical studies

OBJECTIVES

Serotonin (5-hydroxytryptamine, 5-HT) was implicated in the pathophysiology of manic-depressive illness as early as 1958. Although extensive evidence has accumulated since then to support 5-HT's role in depression, relatively fewer studies examined its role in mania. The purpose of this paper was to review and summarize the current state of knowledge on the role of 5-HT in mania and its treatment.

METHODS

We systemically reviewed clinical studies of 1) 5-HT function in mania and 2) 5-HT in the mechanism of action of mood stabilizers, including lithium and anticonvulsants.

RESULTS

Review showed that cerebrospinal fluid, postmortem, platelet, neuroendocrine challenge, and tryptophan depletion studies provided some evidence to support the hypothesis that a 5-HT deficit is involved in mania and that enhancement of 5-HT neurotransmission exerts a mood-stabilizing effect.

CONCLUSIONS

There is some evidence from clinical studies for the contribution of 5-HT in mania and in the mechanism of action of mood stabilizers. However, it is very likely that other neurotransmitters also play important roles. Future directions for research include 1) in vivo study of 5-HT receptor subtypes using positron emission tomography, 2) investigation of the interaction between 5-HT and other neurotransmitter systems, and 3) determination of the relationships between diagnostic subtypes of mania and 5-HT function and other neurotransmitter systems.

The anticonvulsant compound gabapentin possesses anxiolytic but not amnesic effects in rats

This report describes the effects of the antiepileptic agent gabapentin on anxiety and memory. Male Wistar rats received intraperitoneal administrations of gabapentin (10, 30 and 100mg/kg), diazepam (1 mg/kg), saline or diazepam vehicle 30 minutes prior to experimental procedures. Animals were: (1) tested on step-down inhibitory avoidance (footshock 0.3 mA) and habituation to an open-field for memory assessment; and (2) submitted to the elevated plus-maze to evaluate the potential anxiolytic effects of gabapentin. Animals treated with gabapentin showed a reduction in anxiety similar to that observed in animals treated with diazepam. Memory was not affected by gabapentin in any of the tests, but was impaired by diazepam. The lack of effects of gabapentin on memory suggest a potential advantage of this drug over compounds with previously known anxiolytic property, which have amnesic effects at doses used for the treatment of anxiety disorders.

The place of anticonvulsants and other putative mood stabilisers in the treatment of bipolar disorder

While lithium is an effective mood stabiliser still in widespread clinical use, a significant proportion of patients either respond poorly or are unable to tolerate its adverse effects. In the 1960s and 1970s preliminary reports of the possible effectiveness of carbamazepine and valproate began to appear, with confirmatory controlled studies being undertaken in the 1980s and 1990s. In recent years, further putative mood-stabilising agents have been described, in particular some of the newer anticonvulsants and the atypical antipsychotics. This paper critically evaluates the current evidential basis for claims for the efficacy of these compounds in bipolar disorder.

Antidepressant-induced bruxism successfully treated with gabapentin

BACKGROUND

Symptoms consistent with bruxism are a common chief complaint in dental practice. The authors describe a case of bruxism likely induced by the antidepressant venlafaxine and successfully treated with gabapentin.

CASE DESCRIPTION

A case of bruxism, anxiety, insomnia and tremor is reported in a man with bipolar disorder that developed a few days after he initiated venlafaxine therapy for depression. The patient's psychiatrist prescribed gabapentin for anxiety symptoms, and shortly thereafter the man experienced a complete resolution of the bruxism.

CLINICAL IMPLICATIONS

On the basis of this case and the available literature, the authors conclude that bruxism secondary to antidepressant therapy may be common. Thus, dentists should inquire about the use of these medications in patients who have bruxism. Gabapentin may offer promise in the treatment of this condition.

Gabapentin: a review of published experience in the treatment of bipolar disorder and other psychiatric conditions

Successful therapy with valproate and carbamazepine in patients with psychiatric disorders led to investigation of other anticonvulsants for similar indications. Gabapentin is a relatively new anticonvulsant being investigated for potential use in the treatment of bipolar disorder (BD), anxiety disorders, behavioral dyscontrol, and substance use disorders. Its favorable side effect profile, absence of the need for therapeutic drug monitoring, and minimal drug interactions give gabapentin a potential role in these indications. Computer searches of the biomedical literature were undertaken to identify all pertinent case reports, case series, and studies of the drug as monotherapy or adjunctive therapy for BD; 10 reports were retrieved. In the treatment of various anxiety disorders, one study, one case report, and one case series were identified. At least one case series described gabapentin therapy for alcohol withdrawal and one case report of the drug for agitation associated with dementia. Published, well-designed studies evaluating the agent's effectiveness as monotherapy for BD are lacking. Its benefit as an adjunctive treatment with other mood stabilizers is also unestablished. Data regarding its efficacy in the treatment of anxiety disorders or manifestations of substance abuse are limited. These areas may deserve further investigation.

New perspectives in the treatment of acute mania: a single case report

1. There is increasing evidence that standard treatment of mania with lithium or neuroleptics fails in many subtypes of mania, e.g. dysphoric mania or rapid cycling, and new strategies are needed. 2. This single case report reports on possibilities and pitfalls in alternative attempts to tackle a severe manic syndrome successfully. 3. In this patient, lamotrigine and valproate, the latter only in an i.v. formulation, led to a relief from mania. 4. It is concluded that the success of this treatment may be due to a common underlying mechanism of action of these drugs, most likely on the level of ion channel regulation, and that further experience with alternative formulations of standard treatments such as valproate i.v. should be collected.