Tiagabine improves panic and agoraphobia in panic disorder patients

National assessment of anti-epileptic drug exposures among pre-teens and adolescents, 2000-2020

BACKGROUND AND OBJECTIVES

Anti-epileptic drugs (AEDs) are increasingly used to treat psychiatric conditions, exposing many children to potentially harmful medications. This includes adolescents, who are at higher risk for self-harm. The purpose of this study was to describe the epidemiology of pediatric AED poisonings and assess which AEDs are associated with more severe clinical outcomes.

METHODS

This retrospective cross-sectional analysis examined single-substance AED exposure cases in pre-teens (10-14 years) and adolescents (15-19 years) reported to the National Poison Database System (NPDS) between 2000 and 2020 (cases through 2019 were included for trend analysis due to incomplete population data). We described characteristics of ingestions by age group, including AEDs implicated.

RESULTS

There were 74,818 AED exposure cases reported to the NPDS, including 25,928 (34.7%) in pre-teens and 48,890 (65.3%) in adolescents. Among adolescents, 35,570 (72.8%) exposure cases were intentional, with 27,655 (56.6%) specifically related to a suspected suicide attempt. The most common AEDs implicated in poisonings were clonazepam (19.8%), valproic acid (15.3%), and lamotrigine (13.8%). The odds of hospitalization (adjusted odds ratio [aOR] 2.0 [95% confidence interval [CI], 2.0-2.1]), intubation (aOR 2.1 [95% CI, 1.8-2.4]), seizure (aOR 1.6 [95% CI, 1.4-1.9]), and serious outcome (aOR 1.8 [95% CI, 1.7-1.9]) were higher in the adolescent group compared to the pre-teen group. Intentional ingestions increased by a yearly rate of 2.8% (95% CI, 2.3-3.2). Intentional tiagabine exposure was associated with the greatest increased odds of serious outcome (aOR 4.7 [95% CI, 3.6-6.3]).

DISCUSSION

In this cross-sectional analysis of pediatric AED exposure cases reported to the NPDS, AED poisonings among pre-teens and adolescents increased significantly between 2000 and 2019. Of particular concern is the large increase in intentional exposure cases related to AEDs. With the population-adjusted rate of epilepsy diagnoses remaining relatively unchanged, these results may indicate that the rise in AED exposure cases may be related to increased prescribing of AEDs for psychiatric indications as opposed to epilepsy.

CONCLUSIONS

Pediatric AED poisonings reported to the NPDS are increasing, especially among adolescents engaging in intentional ingestions. These findings provide additional information for consideration in risk-benefit assessments when selecting medications for the treatment of psychiatric conditions in children.

Anticonvulsant and antipsychotic medications in the pharmacotherapy of panic disorder: a structured review

BACKGROUND

As the remission rate of panic disorder (PD) achieved with conventional pharmacotherapy ranges between 20% and 50%, alternative psychopharmacological strategies are needed. We aimed to firstly review data regarding use of antipsychotic and non-benzodiazepine anticonvulsant medication in PD patients with or without comorbidities; secondly, to review data concerning reduction of panic symptoms during treatment of another psychiatric disorder with the same medications; and thirdly, to examine reports of anticonvulsant- or antipsychotic-induced new-onset panic symptomatology.

METHODS

We performed a PubMed search (last day: 28 April 2020) of English-language studies only, combining psychopathological terms (e.g. 'panic disorder') and terms referring either to categories of psychotropic medications (e.g. 'anticonvulsants') or to specific drugs (e.g. 'carbamazepine'). All duplications were eliminated. All studies included in the review met certain inclusion/exclusion criteria. The level of evidence for the efficacy of each drug was defined according to widely accepted criteria.

RESULTS

In treatment-resistant PD, beneficial effects have been reported after treatment (mostly augmentation therapy) with a range of anticonvulsant (carbamazepine, gabapentin, lamotrigine, levetiracetam, oxcarbamazepine, valproate, vigabatrin, tiagabine) and antipsychotic (aripiprazole, olanzapine, risperidone, sulpiride) medications: overall, most medications appear generally well tolerated. Additionally, bipolar patients receiving valproate or quetiapine-XR (but not risperidone or ziprasidone) demonstrated reductions of comorbid panic-related symptoms. There are case reports of new-onset panic symptoms associated with clozapine, haloperidol, olanzapine and topiramate, in patients with conditions other than PD. The small-to-modest sample size, the lack of control groups and the open-label and short-term nature of most of the reviewed studies hinder definitive conclusions regarding either the short-term and long-term efficacy of antipsychotic and anticonvulsant medications or their potential long-term side effects.

CONCLUSION

Some atypical antipsychotic and anticonvulsant medications may have a role in the treatment of some PD patients, mostly when more conventional approaches have not been successful, but the quality of supporting evidence is limited.

Review of toxicity and trends in the use of tiagabine as reported to US poison centers from 2000 to 2012

BACKGROUND

Tiagabine is a novel antiepileptic that acts by increasing synaptic and extracellular gamma-aminobutyric acid concentrations. Information concerning overdose of tiagabine is limited. After introduction, an increasing number of off-label uses suggested that tiagabine use would increase. However in 2005 and 2008, warnings from the Food and Drug Administration (FDA) were issued on the risk of seizures in non-epileptic and increased suicide ideation. We evaluated the temporal trends associated with these two warnings as well as clinical outcomes from tiagabine overdose.

METHOD

A retrospective review of all single substance tiagabine exposures in National Poison Data System (NPDS) from 2000 to 2012.

RESULTS

A total of 2147 patients had ingested tiagabine, with a mean of 165 year(-1). This was disproportionally distributed, with a steep rise leading up to 2004 (max 559 year(-1)) and then a significant decline (p < 0.05) between 2005 and 2006. The number of cases reported to NPDS mirrored the sales of tiagabine. Clinical effects were predominantly neurological, with the most commonly reported effects being drowsiness (27%), agitation (19%), confusion (12%), seizures (11%), and tachycardia (10%). In all, 758 patients (35%) showed a major or moderate medical outcome, with no deaths reported. A disproportionate share of the major outcomes was in the suicide attempt group (73%). The majority of patients (75%) were treated in a health-care facility (HCF).

CONCLUSIONS

The HCF usage is likely due to high rate of symptomatic patients (59%) and the large proportion of suicide attempt cases. The frequency of tiagabine cases in NPDS mirrored pharmaceutical sales, with steep declines temporally related to the 2005 FDA warning.

Modulation of ion channels in clinical psychopharmacology: adults and younger people

This review focuses on the use of Na(+), Ca(2+) and Cl(-) channel modulators in psychiatric disease. Drugs that modulate ion channels have been used in psychiatry for more than a century, and in this review we critically evaluate clinical research that reports the therapeutic effects of drugs acting on GABA(A), voltage-gated Na(+) and voltage-gated Ca(2+) channels in pediatric and adult patients. As in other fields, the evidence underpinning the use of medicines in younger people is far less robust than for adults. In addition, we discuss some current developments and highlight clinical disorders in which current molecules could be further tested. Notable success stories, such as benzodiazepines (in sleep and anxiety disorders) and antiepileptics (in bipolar disorder), have been the result of serendipitous discoveries or refinements of serendipitous discoveries, as in all other major treatments in psychiatry. Genomic, high-throughput screening and molecular pharmacology discoveries may, however, guide further developments in the future. This could include increased research in promising targets that have been perceived as commercially risky, such as selective α-subunit GABA(A) receptors.

Long-term anxiolytic and antidepressant-like behavioural effects of tiagabine, a selective GABA transporter-1 (GAT-1) inhibitor, coincide with a decrease in HPA system activity in C57BL/6 mice

Gamma-aminobutyric acid (GABA) system plays a pivotal role in the pathophysiology of anxiety and mood disorders. This study was aimed to assess the anxiolytic and antidepressant-like properties of tiagabine, an inhibitor of the GABA transporter-1 (GAT-1), after acute and chronic administration in C57BL/6JOlaHsD mice with paroxetine as a positive control. In first experiments, the acute administration of tiagabine (7.5 mg/kg, orally [PO]) and paroxetine (10 mg/kg PO) induced anxiolytic effects in the elevated plus maze test and the modified hole board test and an antidepressant-like effect in the forced swim test. Chronic application of tiagabine (7.5 mg/kg PO) and paroxetine (10 mg/kg PO) for 22 days revealed an anxiolytic and antidepressant-like efficacy of tiagabine only. In a further experiment, we analysed the impact of chronic tiagabine versus paroxetine treatment on the hypothalamic-pituitary-adrenocortical (HPA) system regulation. GAT-1 blockade induced a setpoint-shift of the stress hormone system toward lower levels as indicated by decreased plasma corticosterone concentrations and attenuated gene expression levels of corticotropin-releasing factor in the paraventricular nucleus of the hypothalamus and of hippocampal steroid receptors. This data indicate that both acute and long-term anxiolytic and antidepressant-like properties of brain GAT-1 inhibition coincide with a reduction in HPA system activity in mice.

Changes in CCK-4 induced panic after treatment with the GABA-reuptake inhibitor tiagabine are associated with an increase in 3alpha,5alpha-tetrahydrodeoxycorticosterone concentrations

There is evidence that gamma-amino-butyric acid type A (GABA(A))-receptor modulating neuroactive steroids play a role in the pathophysiology of panic disorder. Antidepressant treatment has been suggested to stabilize the concentrations of neuroactive steroids. In this pilot study we investigated neuroactive steroid concentrations during GABAergic treatment, which might represent an alternative anxiolytic pharmacotherapeutic strategy. Neuroactive steroid concentrations were determined in 10 healthy subjects treated with tiagabine. To evaluate the anxiolytic effects of tiagabine a cholecystokinin-tetrapeptide (CCK-4) challenge was performed before and after treatment. Treatment with tiagabine led to a significant increase in 3alpha,5alpha-tetrahydrodeoxycorticosterone (3alpha,5alpha-THDOC) from 0.49 to 1.42 nmol/l (Z=-2.80, p=.005), which was significantly correlated with a decrease of panic symptoms in the CCK-4 challenge. Thus, it might be hypothesized that the anxiolytic effects of GABAergic treatment might in part be mediated by their influence on 3alpha,5alpha-THDOC concentrations.

Empirically supported treatments for panic disorder

This article provides an empirical review of the elements and efficacy of both pharmacologic and psychosocial treatments for panic disorder. Both monotherapies and combination treatment strategies are considered. The available evidence suggests that both cognitive behavioral therapy (CBT) and pharmacotherapy (prominently, selective serotonin reuptake inhibitors or serotonin-norepinephrine reuptake inhibitors) are effective first-line agents and that CBT offers particular cost efficacy relative to both pharmacotherapy alone and combined pharmacotherapy and CBT. Predictors of non-response and mechanisms of action are considered, as are novel treatment strategies, including the use of memory enhancers to improve CBT outcome.

World Federation of Societies of Biological Psychiatry (WFSBP) guidelines for the pharmacological treatment of anxiety, obsessive-compulsive and post-traumatic stress disorders - first revision

In this report, which is an update of a guideline published in 2002 (Bandelow et al. 2002, World J Biol Psychiatry 3:171), recommendations for the pharmacological treatment of anxiety disorder, obsessive-compulsive disorder (OCD) and post-traumatic stress disorder (PTSD) are presented. Since the publication of the first version of this guideline, a substantial number of new randomized controlled studies of anxiolytics have been published. In particular, more relapse prevention studies are now available that show sustained efficacy of anxiolytic drugs. The recommendations, developed by the World Federation of Societies of Biological Psychiatry (WFSBP) Task Force for the Pharmacological Treatment of Anxiety, Obsessive-Compulsive and Post-traumatic Stress Disorders, a consensus panel of 30 international experts, are now based on 510 published randomized, placebo- or comparator-controlled clinical studies (RCTs) and 130 open studies and case reports. First-line treatments for these disorders are selective serotonin reuptake inhibitors (SSRIs), serotonin-noradrenaline reuptake inhibitors (SNRIs) and the calcium channel modulator pregabalin. Tricyclic antidepressants (TCAs) are equally effective for some disorders, but many are less well tolerated than the SSRIs/SNRIs. In treatment-resistant cases, benzodiazepines may be used when the patient does not have a history of substance abuse disorders. Potential treatment options for patients unresponsive to standard treatments are described in this overview. Although these guidelines focus on medications, non-pharmacological were also considered. Cognitive behavioural therapy (CBT) and other variants of behaviour therapy have been sufficiently investigated in controlled studies in patients with anxiety disorders, OCD, and PTSD to support them being recommended either alone or in combination with the above medicines.

Impact of loudness dependency of auditory evoked potentials on the panic response to CCK-4

RATIONALE

Experimental panic induction with cholecystokinin-tetrapeptide (CCK-4) has been established as a model to study the pathophysiology of panic disorder. In line with the serotonin (5-HT)-hypothesis of panic disorder it has been suggested that the panicogenic effects of CCK-4 are mediated in part through the 5-HT system. The analysis of the loudness dependency of the auditory evoked potentials (LDAEP) is a valid non-invasive indicator of central serotonergic activity.

METHODS

We investigated the correlation between LDAEP and behavioral, cardiovascular and neuroendocrine panic responses to CCK-4in 77 healthy volunteers and explored whether differences in LDAEP paralleled subjective panic severity. Behavioral panic responses were measured with the panic symptom scale (PSS). Heart rate and ACTH/cortisol plasma concentrations were assessed concomitantly.

RESULTS

LDAEP did not differ between panickers and nonpanickers. Furthermore, LDAEP did not correlate with the behavioral panic response. However, a significant positive correlation between LDAEP and CCK-4 induced HPA-axis activation, which was uniform in panickers and nonpanickers, could be detected.

CONCLUSIONS

The psychological effects of CCK-4 rather are mediated by neurotransmitters others than the endogenous 5-HT system. However, the extent of the neuroendocrine activation related to the CCK-4 panic provocation was correlated with the LDAEP, thereby suggesting that central 5-HT mechanisms are involved in the HPA-axis activation during this challenge paradigm.

Novel treatment approaches for refractory anxiety disorders

The Anxiety Disorders Association of America convened a conference of experts to address treatment-resistant anxiety disorders and review promising novel approaches to the treatment of refractory anxiety disorders. Workgroup leaders and other participants reviewed the literature and considered the presentations and discussions from the conference. Authors placed the emerging literature on new therapeutic approaches into clinical perspective and identified unmet needs and priority areas for future research. There is a relative paucity of efforts addressing inadequate response to anxiety disorder treatment. Systematic efforts to exhaust all therapeutic options and overcome barriers to effective treatment delivery are needed before patients can be considered treatment refractory. Cognitive behavioral therapy, especially in combination with pharmacotherapy, must be tailored to accommodate the effects of clinical context on treatment response. The literature on pharmacologic treatment of refractory anxiety disorders is small but growing and includes studies of augmentation strategies and non-traditional anxiolytics. Research efforts to discover new pharmacologic targets are focusing on neuronal systems that mediate responses to stress and fear. A number of clinical and basic science studies were proposed that would advance the research agenda and improve treatment of patients with anxiety disorders. Significant advances have been made in the development of psychotherapeutic and pharmacologic treatments for anxiety disorders. Unfortunately, many patients remain symptomatic and functionally impaired. Progress in the development of new treatments has great promise, but will only succeed through a concerted research effort that systematically evaluates potential areas of importance and properly uses scarce resources.

The GABA transporter 1 (SLC6A1): a novel candidate gene for anxiety disorders

Recent evidence suggests that the GABA transporter 1 (GAT-1; SLC6A1) plays a role in the pathophysiology and treatment of anxiety disorders. In order to understand the impact of genetic variation within SLC6A1 on pathological anxiety, we performed a case–control association study with anxiety disorder patients with and without syndromal panic attacks. Using the method of sequential addition of cases, we found that polymorphisms in the 5′ flanking region of SLC6A1 are highly associated with anxiety disorders when considering the severity of syndromal panic attacks as phenotype covariate. Analysing the effect size of the association, we observed a constant increase in the odds ratio for disease susceptibility with an increase in panic severity (OR ~ 2.5 in severely affected patients). Nominally significant association effects were observed considering the entire patient sample. These data indicate a high load of genetic variance within SLC6A1 on pathological anxiety and highlight GAT-1 as a promising target for treatment of anxiety disorders with panic symptoms.

Update: new uses for lithium and anticonvulsants

Anticonvulsants are being used clinically as monotherapy and adjuncts in mental illnesses other than affective disorders. This review focuses on the literature for anticonvulsants and lithium in substance use disorders, anxiety disorders, and schizophrenia. Given the abuse potential and other difficulties with prescribing benzodiazepines for alcohol and benzodiazepine withdrawal, anticonvulsants have been considered as an alternative. Promising therapeutic effects have been demonstrated in many of the anxiety disorders, with the greatest number of trials and positive results in posttraumatic stress disorder. Although anticonvulsant and lithium augmentation for schizophrenia is common in practice and has been studied in double-blind, randomized, controlled trials, the sum of the evidence has been inconclusive.

Resistência ao tratamento nos transtornos de ansiedade: fobia social, transtorno de ansiedade generalizada e transtorno do pânico

OBJETIVOS: Os transtornos de ansiedade são condições psiquiátricas prevalentes que determinam importante prejuízo funcional, piora na qualidade de vida do indivíduo e um enorme custo social. Embora diversas medicações eficazes para os transtornos de ansiedade encontrem-se disponíveis, um número significativo de pacientes não responde adequadamente ao tratamento e muitos permanecem com sintomas residuais clinicamente significativos. O objetivo deste estudo é rever aspectos relacionados à resistência ao tratamento e estratégias farmacológicas no manejo dos transtornos de ansiedade resistentes ao tratamento. MÉTODO: Revisão narrativa. RESULTADOS: São discutidos os diversos aspectos conceituais relacionados à resistência ao tratamento, os possíveis preditores de resistência e, finalmente, algumas estratégias a serem utilizadas no manejo dos transtornos de ansiedade (incluindo transtorno de ansiedade social, transtorno de ansiedade generalizada e transtorno do pânico) que não respondem às abordagens terapêuticas convencionais. CONCLUSÃO: A resistência ao tratamento ainda é um desafio para a prática clínica que começa em conceitos não operacionalizados de resposta e resistência e termina na escassez de estudos controlados sobre estratégias de tratamento nesse último cenário clínico.

GABAA receptors as targets for novel anxiolytic drugs

Anxiety disorders are highly prevalent and disabling disorders which are commonly treated with pharmacotherapy and/or psychotherapy. While benzodiazepines are of great value for the treatment of acute anxiety states, their long-term use is hampered by their well-known side effect profile. Meanwhile, antidepressants represent first line treatment options for anxiety disorders. However, their slow onset of action is a disadvantage for their use in these disorders. Therefore, there is need for novel anxiolytics with a rapid onset of action and a favourable side effect profile. Currently, there is a renaissance of gamma-aminobutyric acid type A (GABAA) receptors as targets for the development of novel anxiolytic drugs. While compounds structurally related to GABA, e.g., pregabalin, have already entered large scale clinical development, GABA transporter inhibitors, subtype specific benzodiazepines and GABAA receptor modulating neuroactive steroids are promising new candidates. However, their clinical efficacy has still to be shown in clinical trials.

Tiagabine in anxiety disorders

GABA has been implicated in both the aetiology and treatment of anxiety. Tiagabine is currently the only selective GABA reuptake inhibitor available in US markets; it exerts its action via GAT-1 transporter blockade presynaptically, facilitating GABA neurotransmission. Preclinical studies and current human studies suggest tiagabine possesses anxiolytic properties. The anxiolytic properties of tiagabine have also been suggested in a number of case series, open-label studies and placebo-controlled studies in patients with different anxiety disorders. Throughout these studies, tiagabine has been reasonably tolerated; the most commonly reported adverse events include dizziness, headache and nausea. Tiagabine may be a useful addition to currently available drugs for anxiety; however, the data from small open-label investigations remain to be confirmed in larger controlled studies.

Saccadic eye velocity after selective GABAergic treatment with tiagabine in healthy volunteers

BACKGROUND

Saccadic eye velocity (SEV) has been shown to be a reliable neurophysiological tool for the assessment of gamma-aminobutyric acid GABA(A) receptor sensitivity. Administration of benzodiazepines targeting the GABA(A) receptor decreases SEV in healthy volunteers. Tiagabine is a new antiepileptic drug which acts via selective blockade of GABA reuptake. Therefore, we examined the effects of tiagabine on saccade parameters.

METHODS

SEV was analyzed in 8 healthy volunteers before and after 7 days of tiagabine treatment. Subjects received tiagabine in a daily dose of 15 mg. Saccades were measured using a noninvasive infrared oculographic device. Amplitude, latency, and SEV were analyzed as a function of treatment and target eccentricity.

RESULTS

SEV and saccade latency increased with target amplitude. Treatment with tiagabine had no significant effect on SEV and saccade amplitude. A trend was found for increased latencies after tiagabine.

CONCLUSION

In contrast to findings with benzodiazepines, tiagabine treatment had no impact on SEV in healthy volunteers. The subchronic tolerance effects or the different site of action on the GABA(A)/BZD receptor complex may account for this deviating profile.

Effects of tiagabine in combination with intravenous nicotine in overnight abstinent smokers

RATIONALE

Preclinical studies suggest that medications enhancing the brain gamma amino butyric acid (GABA) system attenuate the rewarding effects of stimulants including nicotine. These preclinical studies have not been followed up in systematic human studies.

OBJECTIVES

This study was conducted to examine the effects of a GABAergic medication, tiagabine, on acute physiological and subjective effects of intravenous (i.v.) nicotine and on tobacco withdrawal symptoms in overnight abstinent smokers. The proposed mechanism of action for tiagabine is selective inhibition of GABA transporter type I, which leads to increases in synaptic GABA levels.

METHODS

Eight male and four female smokers participated in a double-blind, placebo-controlled, crossover study. In each of three experimental sessions, participants were treated orally with a single 4- or 8-mg dose of tiagabine or placebo. Two hours following the medication treatment, participants received i.v. saline, followed 30 min later by 1.5 mg/70 kg i.v. nicotine.

RESULTS

Tiagabine treatment did not affect the heart rate or blood pressure changes induced by nicotine. There was a significant treatment effect for the subjective responses to nicotine, such that tiagabine, compared to placebo, attenuated the ratings of "good effects" and "drug liking." Tiagabine treatment at 8 mg attenuated the craving for cigarettes and enhanced the cognitive performance in the Classical Stoop Tests, compared to placebo or 4 mg tiagabine condition.

CONCLUSIONS

These results suggest that GABA enhancing medication tiagabine may reduce the rewarding effects of nicotine and improve cognitive performance in abstinent smokers. The utility of GABA medications for smoking cessation needs to be examined further in controlled clinical trials.

Anticonvulsants in anxiety disorders

Anticonvulsant drugs have shown promising results in the treatment of mood disorders, leading to the investigation of their potential efficacy in other psychiatric disorders. Numerous case reports, open-label trials, and placebo- controlled trials investigating the use of anticonvulsants in the treatment of anxiety disorders have yielded broad and varying results. Generally, these studies have indicated a potential role for anticonvulsants in the treatment of anxiety as monotherapy or augmentation therapy; however, these early findings must be supported by additional investigation in large-scale, placebo-controlled studies. This article reviews past and current research being done in this novel area of psychopharmacology.

Effects of tiagabine on cholecystokinin-tetrapeptide (CCK-4)-induced anxiety in healthy volunteers

There is increasing evidence that a dysregulation of the gamma-aminobutyric acid (GABA) system plays a role in the pathophysiology of panic disorder. Selective enhancement of GABAergic neurotransmission has been shown to improve anxiety in experimental animals and in patients with panic disorder. Tiagabine is an antiepileptic drug, which increases GABA via selective blockade of GABA reuptake. Apart from its anticonvulsant activity anxiolytic properties could therefore be suggested. To investigate the putative anxiolytic properties of the GABA reuptake blocker tiagabine, we studied the impact of tiagabine treatment on cholecystokinin tetrapeptide (CCK-4)-induced panic. Fifteen healthy volunteers received 15 mg tiagabine daily for 1 week. A CCK-4 challenge was performed before and after treatment. Panic was assessed using the API- and PSS-score. There was a marked improvement of CCK-4-induced panic after 1 week of treatment. Both API- and PSS-scores showed a significant reduction. Our results suggest anxiolytic properties of tiagabine in humans, which provide sufficient rationale to assess its putative anxiolytic effects in patients with panic disorder under controlled conditions.