Safety of tiagabine: summary of 53 trials

Tiagabine and zonisamide differentially regulate the glial properties in an astrocyte-microglia co-culture model of inflammation

Due to the role of astrocytes and microglia in the pathophysiology of epilepsy and limited studies of antiseizure medication (ASM) effects on glial cells, we studied tiagabine (TGB) and zonisamide (ZNS) in an astrocyte-microglia co-culture model of inflammation. Different concentrations of ZNS (10, 20, 40, 100 µg/ml) or TGB (1, 10, 20, 50 µg/ml) were added to primary rat astrocytes co-cultures with 5-10% (M5, physiological conditions) or 30-40% (M30, pathological inflammatory conditions) microglia for 24 h, aiming to study glial viability, microglial activation, connexin 43 (Cx43) expression and gap-junctional coupling. ZNS led to the reduction of glial viability by only 100 µg/ml under physiological conditions. By contrast, TGB revealed toxic effects with a significant, concentration-dependent reduction of glial viability under physiological and pathological conditions. After the incubation of M30 co-cultures with 20 µg/ml TGB, the microglial activation was significantly decreased and resting microglia slightly increased, suggesting possible anti-inflammatory features of TGB under inflammatory conditions. Otherwise, ZNS caused no significant changes of microglial phenotypes. The gap-junctional coupling was significantly decreased after the incubation of M5 co-cultures with 20 and 50 µg/ml TGB, which can be related to its anti-epileptic activity under noninflammatory conditions. A significant decrease of Cx43 expression and cell-cell coupling was found after the incubation of M30 co-cultures with 10 µg/ml ZNS, suggesting additional anti-seizure effects of ZNS with the disruption of glial gap-junctional communication under inflammatory conditions. TGB and ZNS differentially regulated the glial properties. Developing novel ASMs targeting glial cells may have future potential as an "add-on" therapy to classical ASMs targeting neurons.

Synthesis and biological evaluation of novel N-substituted nipecotic acid derivatives with tricyclic cage structures in the lipophilic domain as GABA uptake inhibitors

A new class of GABA reuptake inhibitors with sterically demanding, highly rigid tricyclic cage structures as the lipophilic domain was synthesized and investigated in regard to their biological activity at the murine GABA transporters (mGAT1–mGAT4). The construction of these compounds, consisting of nipecotic acid, a symmetric tricyclic amine, and a plain hydrocarbon linker connecting the two subunits via their amino nitrogens, was accomplished via reductive amination of a nipecotic acid derivative with an N-alkyl substituent displaying a terminal aldehyde function with tricyclic secondary amines. The target compounds varied with regard to spacer length, the bridge size of one of the bridges, and the substituents of the tricyclic skeleton to study the impact of these changes on their potency. Among the tested compounds nipecotic acid ethyl ester derivates with phenyl residues attached to the cage subunit showed reasonable inhibitory potency and subtype selectivity in favor of mGAT3 and mGAT4, respectively.

N-Substituted Nipecotic Acids as (S)-SNAP-5114 Analogues with Modified Lipophilic Domains

Potential mGAT4 inhibitors derived from the lead substance (S)-SNAP-5114 have been synthesized and characterized for their inhibitory potency. Variations from the parent compound included the substitution of one of its aromatic 4-methoxy and 4-methoxyphenyl groups, respectively, with a more polar moiety, including a carboxylic acid, alcohol, nitrile, carboxamide, sulfonamide, aldehyde or ketone function, or amino acid partial structures. Furthermore, it was investigated how the substitution of more than one of the aromatic 4-methoxy groups affects the potency and selectivity of the resulting compounds. Among the synthesized test substances (S)-1-{2-[(4-formylphenyl)bis(4-methoxyphenyl)-methoxy]ethyl}piperidine-3-carboxylic acid, that features a carbaldehyde function in place of one of the aromatic 4-methoxy moieties of (S)-SNAP-5114, was found to have a pIC50 value of 5.89±0.07, hence constituting a slightly more potent mGAT4 inhibitor than the parent substance while showing comparable subtype selectivity.

Development of Positron Emission Tomography Radiotracers for the GABA Transporter 1

In vivo positron emission tomography (PET) imaging of the γ-aminobutyric acid (GABA) receptor complex has been accomplished using radiolabeled benzodiazepine derivatives, but development of specific presynaptic radioligands targeting the neuronal membrane GABA transporter type 1 (GAT-1) has been less successful. The availability of new structure-activity studies of GAT-1 inhibitors and the introduction of a GAT-1 inhibitor (tiagabine, Gabatril) into clinical use prompted us to reinvestigate the syntheses of PET ligands for this transporter. Initial synthesis and rodent PET studies of N-[¹¹C]methylnipecotic acid confirmed the low brain uptake of that small and polar molecule. The common design approach to improve blood-brain barrier permeability of GAT-1 inhibitors is the attachment of a large lipophilic substituent. We selected an unsymmetrical bis-aromatic residue attached to the ring nitrogen by a vinyl ether spacer from a series recently reported by Wanner and coworkers. Nucleophilic aromatic substitution of an aryl chloride precursor with [¹⁸F]fluoride was used to prepare the desired candidate radiotracer ( R, E/ Z)-1-(2-((4-fluoro-2-(4-[¹⁸F]fluorobenzoyl)styryl)oxy)ethyl)piperidine-3-carboxylic acid (( R, E/ Z)-[¹⁸F]10). PET studies in rats showed no brain uptake, which was not altered by pretreatment of animals with the P-glycoprotein inhibitor cyclosporine A, indicating efflux by Pgp was not responsible. Subsequent PET imaging studies of ( R, E/ Z)-[¹⁸F]10 in rhesus monkey brain showed very low brain uptake. Finally, to test if the free carboxylic acid group was the likely cause of poor brain uptake, PET studies were done using the ethyl ester derivative of ( R, E/ Z)-[¹⁸F]10. Rapid and significant monkey brain uptake of the ester was observed, followed by a slow washout over 90 min. The blood-brain barrier permeability of the ester supports a hypothesis that the free acid function limits brain uptake of nipecotic acid-based GAT-1 radioligands, and future radiotracer efforts should investigate the use of carboxylic acid bioisosteres.

Managing aggression in epilepsy

Behavioural changes associated with epilepsy can be challenging for patients and clinicians. Evidence suggests an association between aggression and epilepsy that involves various neurophysiological and neurochemical disturbances. Anti-epileptics have variable effects on behaviour and cognition that need consideration. Early detection and careful consideration of history, symptomatology and possible common comorbid psychiatric disorders is essential. Appropriate investigations should be considered to aid diagnosis, including electroencephalogram (EEG), video EEG telemetry and brain imaging. Optimising treatment of epilepsy, treatment of psychiatric comorbidities and behavioural management can have a major positive effect on patients' recovery and well-being.

Learning Objectives

• Understand the epidemiology of aggression in epilepsy

• Comprehend the link between anti-epileptics and aggression, including the important role of pharmacodynamics

• Be aware of the pharmacological treatments available for managing aggressive behaviour in epilepsy

Tolerability and Safety of Commonly Used Antiepileptic Drugs in Adolescents and Adults: A Clinician's Overview

This paper discusses the issues surrounding the tolerability and safety of the commonly used antiepileptic drugs (AEDs) in adolescents and adults. The content includes dose-related adverse effects, idiosyncratic reactions, behavioural and psychiatric comorbidities, chronic problems, enzyme induction and teratogenesis. Twenty-one AEDs are discussed in chronological order of their introduction into the UK, starting with phenobarbital and ending with brivaracetam. Wherever possible, advice is given on anticipating, recognising and managing these issues and thereby improving the lives of people with epilepsy, most of whom will need to take one or more of these agents for life. Avoidance of side effects will increase the possibility of achieving and maintaining long-term seizure freedom. Alternatively, adverse events from AEDs will substantially reduce quality of life and often result in higher healthcare costs.

Study of psychiatric comorbidities in epilepsy by using the Mini International Neuropsychiatric Interview

BACKGROUND

Epilepsy is a neurological condition affecting men and women of all age groups and is associated with psychiatric comorbid conditions. There is a paucity of published data available regarding psychiatric comorbid conditions in patients with epilepsy (PWEs) from developing countries.

METHODS

We compared the psychiatric comorbid conditions in 80 PWEs, 80 patients with asthma (asthma control (AC) subjects), and 80 healthy controls (normal control (NC) subjects) using the Mini International Neuropsychiatric Interview (MINI) for the diagnosis of Axis I psychiatric disorders.

RESULTS

Psychiatric comorbid conditions are more common in PWEs (32.50%) as compared with the AC (17.5%) and NC (7.5%) subjects. Longer duration of seizures, increased frequency of seizures, recent recurrence of seizures, anticonvulsant polypharmacy, poor compliance with medications, and family history of seizures were associated with increased psychiatric comorbidity.

CONCLUSION

Patients with epilepsy are more likely to have psychiatric comorbid disorders compared with the other patients with chronic illness or with the healthy controls. It is of immense clinical importance to identify the comorbid psychiatric disorders in PWEs as the treatment of these disorders apart from a good seizure control may significantly improve their quality of life.

Tiagabine for acute affective episodes in bipolar disorder

BACKGROUND

Bipolar disorder is a common recurrent illness with high levels of chronicity. Treatment resistance persists despite the use of established medications, such as lithium and valproate. New medications are required for the treatment of refractory cases. Some open-label reports have suggested that the anticonvulsant tiagabine may be efficacious in bipolar disorder. There is a need to clarify the evidence available, in the form of randomised controlled trials, for its use in the treatment of acute affective episodes in bipolar disorder.

OBJECTIVES

To review the evidence for the efficacy and acceptability of tiagabine in the treatment of acute mood episodes in bipolar disorder.

SEARCH METHODS

In this update, we searched the Cochrane Depression, Anxiety and Neurosis Group's Specialised Register (CCDANCTR-Studies and CCDANCTR-References) to October 2012. This register contains relevant randomised controlled trials from: The Cochrane Library (all years), EMBASE (1974 to date), MEDLINE (1950 to date) and PsycINFO (1967 to date). We examined reference lists of relevant papers and major textbooks of affective disorder. We contacted authors, other experts in the field and pharmaceutical companies for knowledge of suitable published or unpublished trials. We handsearched specialist journals and conference proceedings.

SELECTION CRITERIA

Randomised controlled trials, which compared tiagabine with placebo or with active agents in the treatment of any acute mood episodes in bipolar disorder in adults, male and female, aged 18 to 74 years.

DATA COLLECTION AND ANALYSIS

Two review authors performed data extraction and methodological quality assessment independently. For analysis, we planned to use risk ratio for binary efficacy outcomes and mean difference or standardised mean difference for continuously distributed outcomes.

MAIN RESULTS

In this updated review we found no studies which fulfilled the Cochrane criteria for randomised controlled trials.

AUTHORS' CONCLUSIONS

We found no randomised controlled trials of tiagabine in the treatment of acute episodes of bipolar disorder. However, there are reports that a number of patients suffered episodes of syncope or seizure. Further investigation of the efficacy and acceptability of tiagabine in the treatment of acute affective episodes of bipolar disorder should await the clarification of the nature of the reported episodes of syncope and seizure-like activity and an examination of the level of risk involved.

Psychiatric symptomatologies and disorders related to epilepsy and antiepileptic medications

INTRODUCTION

Psychiatric comorbidities (such as depression, anxiety, psychosis, inattention, obsession, personality traits, aggression and suicide) are frequent in patients with epilepsy and have a significant impact on medical management and quality of life.

AREAS COVERED

A literature search was performed in MEDLINE for epidemiological, longitudinal, prospective, double-blind clinical trial studies published between 1990 and 2011 using the following words: epilepsy, antiepileptic drugs (AEDs), behavioral/emotional/psychiatric comorbidities, suicide and aggression. In this review, the author discusses: i) the characterization and prevalence of behavioral disturbances associated with epilepsy, ii) variables correlated with behavioral comorbidities which include: psychosocial-, clinical- and treatment-related variables, iii) the complex mechanisms of behavioral comorbidities associated with epilepsy, which include both psychosocial (functional) and organic; the process of epileptogenesis, neuronal plasticity, abnormalities in hypothalamic-pituitary axis and neurotransmitters and pathways are fundamental determinants, iv) the negative psychotropic effects of AEDs and their mechanisms and v) the suggested biopsychosocial model of management (pharmacological and non-pharmacological).

EXPERT OPINION

The relationship between psychiatric disorders and epilepsy has relevant therapeutic implications which should be directed towards a comprehensive biopsychosocial approach that focuses on the whole person rather than simply on the disease process.

The safety and tolerability of newer antiepileptic drugs in children and adolescents

The newer antiepileptic drugs (AEDs) provide more therapeutic options and overall improved safety and tolerability for patients. To provide the best care, physicians must be familiar with the latest tolerability and safety data. This is particularly true in children, given there are relatively fewer studies examining the effects of AEDs in children compared with adults. Since we now have significant paediatric literature on each of these agents, we provide a comprehensive and current literature review of the newer AEDs, focusing on safety and tolerability data in children and adolescents. Because the safety profiles in children differ from those in adults, familiarity with this literature is important for child neurologists and other paediatric caregivers. We have organized the data by organ system for each AED for easier reference.

Depression and anxiety in children and adolescents with epilepsy: prevalence, risk factors, and treatment

Among the psychiatric comorbid conditions in children and adolescents with epilepsy, depression and anxiety disorders require further attention because they carry the risk of reduced quality of life and life-threatening complications (e.g., suicide). Research in recent years has shed light on both the prevalence of emotional problems in youth with epilepsy and the safety and efficacy of treatment options. A number of challenges exist in treating patients with epilepsy. This is particularly true when seizures are difficult to control and medication regimens are more complex. Some pharmaceutical options may provide assistance with both seizures and emotional distress, but care is needed when considering such treatment approaches. In addition, integration of mental health professionals into the care of patients is necessary when cases are complicated and risk factors are high. Thorough methods to accurately diagnose emotional conditions and regular monitoring of symptoms can help prevent serious problems that can negatively affect the success of children and adolescents in everyday life. Collaboration between disciplines offers the best hope for early identification and treatment of these conditions.

Seizures in a pediatric patient with a tiagabine overdose

INTRODUCTION

Tiagabine (TGB) is a novel antiepileptic that decreases GABA uptake. The literature contains one report of an adult with epilepsy who ingested up to 1 gram of TGB and developed status epilepticus. We reported on a pediatric patient who ingested significantly less TGB but still developed tonic-clonic seizures.

CASE REPORT

A previously healthy, 13 kg, two-year-old girl developed generalized tonic-clonic seizure activity at home approximately 1 hour after ingesting 90 mg of her grandmother's TGB (forty five 2 mg tablets). At the hospital she had two 5 minute seizures at 1.5 and 3.5 hours post ingestion. Her serum TGB levels were 530 and 130 ng/ml approximately 5 and 11 hours post-ingestion (5-70 ng/ml trough levels with most probable range for seizure control). She was discharged 27 hours post ingestion, and she was in good condition.

CONCLUSION

An overdose of TGB, a novel anti-epileptic, can cause convulsive seizures.

Antiepileptic drugs and visual function

Antiepileptic drugs are known to result in visual disturbances. A number of antiepileptic drugs have recently been reported to result in various abnormalities of vision, particularly deficiencies in visual fields and color vision. Moreover, there has been a marked improvement in the diagnosis and understanding of the pathophysiology of visual disturbance. This review collects evidence for visual adverse effects induced by the older antiepileptic drugs (barbiturates, benzodiazepine, carbamazepine, valproic acid, ethosuximide, and phenytoin) and the newer ones (vigabatrin, topiramate, tiagabine, levetiracetam, lamotrigine, gabapentin, felbamate, and oxcarbazepine).

Currently available antiepileptic drugs

Many new antiepileptic drugs (AEDs) have become available over the past 15 years. At the same time, the emphasis on treating patients with epilepsy has grown from stopping seizures to avoiding side effects and maximizing quality of life. This review summarizes currently available AEDs, and presents general treatment principles and guidelines for AED selection. Unfortunately, despite the increased treatment options of today, seizure freedom without side effects remains unattainable for too many patients with epilepsy. Consequently, there remains a significant need for further development of new therapies.

The ethics of excluding women who become pregnant while participating in clinical trials of anti-epileptic medications

INTRODUCTION

The bioethical principles of autonomy, beneficence, non-maleficence and justice, complemented by ethics committee evaluation, define conduct of clinical trials of anti-epileptic medications (AEM).

BACKGROUND INFORMATION

Increased teratogenicity for offspring of women with epilepsy is presented in both lay and scientific literature. SPECIFIC DRUGS--OLDER GENERATION: Teratogenicity of phenobarbitone (PB), phenytoin (PHT), valproate (VPA) and carbamazepine (CBZ) is acknowledged, with drugs, such as trimethadione, being removed from the market because of teratogenicity. SPECIFIC DRUGS--NEW GENERATION: Insufficient data allowed definitive commentary concerning teratogenicity of newer AEM, such as lamotrigine (LTG), gabapentin (GBP), tiagabine (TGB) or levetiracetam (LEV). All those suggestions favour some over others with specific AEM combinations being questioned. PREGNANCY REGISTRIES: Lack of information sporn AEM-specific plus national and international birth registries which endorse VPA, CBZ and LTG dose related concerns.

CONFLICT OF INTEREST

Competing influences of AEM and epilepsy-specific factors need delineation although appear more teratogenetic than does epilepsy alone.

CLINICAL TRIALS

Most trials focus upon refractory epilepsy with potentially enhanced risks. Informed consent demands discussion of possible teratogenicity and exclusion of women unwilling to practice adequate contraception.

DISCUSSION

Trials must respect legal and ethical dictates including the exclusion of women unwilling to practice reliable contraception. Automatic exclusion from a trial, subsequent to confirmed pregnancy, is unlikely to protect the foetus as potential for teratogenicity already has occurred. Autonomy should empower prospective parents to decide continued trial participation consequent to detailed informed consent without coercion. All options demand review, including responsibility to future AEM users.

Tiagabine in the treatment of acute affective episodes in bipolar disorder: efficacy and acceptability

BACKGROUND

Bipolar disorder is a common recurrent illness with high levels of chronicity. Treatment resistance persists despite the use of established medications, such as lithium and valproate. New medications are required for the treatment of refractory cases. Some open-label reports have suggested that the anticonvulsant tiagabine may be efficacious in bipolar disorder. There is a need to clarify the evidence available, in the form of randomised controlled trials, for its use in the treatment of acute affective episodes in bipolar disorder

OBJECTIVES

To review the evidence for the efficacy and acceptability of tiagabine in the treatment of acute mood episodes in bipolar disorder.

SEARCH STRATEGY

The following databases were searched on 13-10-2005. The Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Registers (CCDANCTR-Studies and CCDANCTR-References),The Cochrane Controlled Clinical Trials Register (CCCTR),EMBASE,MEDLINE,LILACS,PsycLIT andPsyndex. Reference lists of relevant papers and major textbooks of mood disorder were searched. Handsearches were done (specialist journals and conference proceedings). Authors, other experts in the field and pharmaceutical companies were contacted for knowledge of suitable published or unpublished trials.

SELECTION CRITERIA

Randomised controlled trials, which compared tiagabine with placebo or with active agents in the treatment of any acute mood episodes in bipolar disorder, were selected. Studies of participants with bipolar disorder were to be included. Subjects could be of either sex and of all ages.

DATA COLLECTION AND ANALYSIS

Data extraction and methodological quality assessment were performed independently by two reviewers. For analysis, relative risk was used for binary efficacy outcomes and the weighted mean difference or standardised mean differerence was used for continuously distributed outcomes

MAIN RESULTS

We did not find any studies which fulfilled the Cochrane criteria of randomised controlled trials. However, one uncontrolled open label study and one case series were found. There were also three case reports/series of acute treatment which were continued into maintenance therapy, and one open non-randomised study with this design. The results of these studies are inconsistent.

AUTHORS' CONCLUSIONS

We found no randomised controlled trials of tiagabine in bipolar disorder. In the reported cases, a significant proportion of patients suffered episodes of syncope or seizure. There is a need for randomised controlled trials examining the efficacy and acceptability of tiagabine in the acute treatment of bipolar disorder, after the nature of these episodes has been clarified.

Transient athetosis induced by tiagabine

Movement disorders have been reported with use of different antiepileptic drugs (AEDs). We report a 32-year-old woman, affected by a symptomatic focal drug-resistant epilepsy and a mild hemiparesis, with acute athetoid movements, transiently linked to increasing tiagabine (TGB) therapy. To our knowledge, no other cases of acute athetosis related to TGB have been reported to date. However, we cannot rule out the possibility that involuntary movements were induced by an interaction between TGB and concomitant AEDs, in particular phenobarbital (PB), possibly by increasing GABAergic transmission. We hypothesize that the presence of a static encephalopathy may have influenced the kind of extrapyramidal side effect induced by TGB in our patient, leading to athetosis.

Retrospective evaluation of tiagabine overdose

BACKGROUND

Tiagabine is an anticonvulsant that blocks reuptake of the inhibitory neurotransmitter GABA. There are no published studies or case series of tiagabine overdoses.

METHODS

The records of six poison centers and one statewide poison center network were searched for all exposures to tiagabine for the years 2000-2002. Inclusion criterion was a human tiagabine exposure with follow-up to a known outcome; exclusion criterion was multiple drug ingestion.

RESULTS

57 cases met the inclusion criterion. Thirty-seven patients were female (67%). Mean and median ages were 30.5 years (S.D. +/- 18.5) and 31 years, respectively, with a range of 2 to 80 years. Seven patients were < or = 6 years. Neurologic symptoms were common: lethargy, seizures (multiple), status epilepticus, seizure (single), coma, confusion, agitation, tremors, dizziness, dystonias/abnormal posturing, and hallucinations. Other symptoms included respiratory depression, tachycardia, hypertension, and hypotension. Therapies included benzodiazepines, mechanical ventilation, phenytoin, phenobarbital, diphenhydramine, and dopamine. The mean onset and duration of symptoms were 1.3 hours (+/- 0.5, range 1-2 hours) and 9.1 hours (+/- 3.8, range 4-24 hours), respectively. Dose ingested by history was known for 38 patients (67%). The lowest dose with the development of multiple seizures and coma was 96 mg. This occurred in a 36-year-old female with a history of epilepsy. The lowest dose with symptoms in a child was 8 mg, in a 6-year-old with drowsiness. Mean dose of those with and without symptoms was 102 mg and 10 mg, respectively. The mean dose for patients experiencing seizures was 224 mg (+/- 172, range 96 to 680 mg). The mean dose for patients experiencing coma and respiratory depression was 270 mg (+/- 204, range 96 to 680 mg). Fifty-two patients (91%) were evaluated in the ED of whom 43 were admitted for medical care.

CONCLUSION

Seizures and altered mental status were common with tiagabine overdose, with rapid onset and resolution of symptoms. In this series, seizures did not occur until the ingestion was greater than three times the maximum recommended daily dose.

Color vision and contrast sensitivity in epilepsy patients treated with initial tiagabine monotherapy

The purpose of the study was to determine whether the use of a GABAergic antiepileptic drug (AED), tiagabine, affects color vision and contrast sensitivity. Twenty newly diagnosed patients with partial epilepsy (aged 19-72 years), receiving tiagabine as their initial monotherapy for 5-41 months were examined. Color vision was examined with the Standard Pseudoisochromatic Plates 2 (SPP2), with the Farnsworth-Munsell 100 Hue Test (FM100) and with the Color Vision Meter 712 (CVM) anomaloscope. Contrast sensitivity was measured with the Pelli-Robson letter chart. Three patients excluded from the color vision evaluation for congenital red-green color vision defects. Seven out of 17 patients (41%) had acquired color vision deficit examined with the FM100. The CVM anomaloscope revealed minor defects in two patients. Contrast sensitivity function was within normal ranges. The present study suggests that AED therapy with tiagabine, like with other established and newer AEDs may interfere with color perception.

Safety of antiepileptic drugs during pregnancy

Women with epilepsy taking antiepileptic drugs during pregnancy have been shown to have an increased risk of having a child with a major malformation. There is some recent evidence to suggest that these drugs may also affect cognitive and behavioural development. Epilepsy is a common neurological condition and women with epilepsy constitute a significant number of pregnancies in the UK each year. Some of the drugs used to treat epilepsy are increasingly being used in the treatment of migraine and other pain syndromes and also in psychiatry principally for the control of bipolar affective disorder. This article looks at the evidence currently available in assessing the safety of the individual agents used in pregnancy.

An open-label study of tiagabine as augmentation therapy for anxiety

BACKGROUND

At least 50% of patients with anxiety disorders experience only partial response to pharmacotherapy and require augmentation therapy. Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the CNS, and agents that modulate GABA neurotransmission have shown promise in the treatment of anxiety disorders and are often used as augmentation agents.

OBJECTIVE

This study evaluated tiagabine, a selective GABA reuptake inhibitor (SGRI), as augmentation therapy.

METHODS

This 8-week, open-label study enrolled patients who remained symptomatic despite adequate drug trials for treatment of anxiety symptoms. Tiagabine augmentation therapy was initiated at 4 mg/d (taken in 2 doses; one in the morning with breakfast and one in the evening with a snack) for 2 days and increased to 8 mg/d for 10 days. Dose was then adjusted according to efficacy/tolerability in increments of 2 mg every 3 days up to a maximum of 20 mg/d. Effect was assessed using the Hamilton Rating Scale for Anxiety (HAM-A), Beck Anxiety Inventory (BAI), Clinical Global Impression (CGI) scale, Pittsburgh Sleep Quality Index (PSQI), and 36-item Short-Form Health Survey (SF-36).

RESULTS

Of the 18 patients enrolled, 17 were included in the efficacy analysis; one withdrew due to an adverse event prior to post-baseline assessment. Mean final dose of tiagabine was 13 mg/d. Tiagabine as augmentation therapy further reduced anxiety symptoms, as shown by significant decreases in mean HAM-A total and BAI scores at Week 8 (P<0.001). Thirteen patients (76%) responded (> or =50% reduction in HAM-A total score), and 10 patients (59%) achieved remission (HAM-A total score < or =7) at Week 8. Tiagabine improved sleep quality, with a significant reduction seen in PSQI global score at Week 8 (P=.001). Augmentation therapy with tiagabine was generally well tolerated.

CONCLUSION

These preliminary findings suggest that the SGRI tiagabine may be an effective and generally well tolerated augmentation therapy in patients with anxiety who remain symptomatic despite adequate drug trials for treatment of anxiety symptoms.

Treating refractory epilepsy with tiagabine: clinical experience

Epilepsy remains difficult to treat with more than 30% of patients being refractory to conventional anticonvulsant therapy. Combination therapy may improve seizure control in some of these patients. Tiagabine is a new anticonvulsant that has a unique mechanism of action as a selective gamma-aminobutyric acid (GABA) re-uptake inhibitor (SGRI). Twenty consecutive patients with refractory epilepsy were treated with tiagabine, and prior to tiagabine administration the mean number of anticonvulsants that each patient had taken was five. Tiagabine therapy was initiated at a dose of 5 or 10mg per day and was increased at weekly increments of 5 or 10 mg per day, respectively. Thirty-five percent of patients receiving tiagabine (20-40 mg per day, mean 34.29 mg per day) achieved a > or =50% reduction in seizure frequency. Tiagabine was effective when added to carbamazepine, lamotrigine, or oxcarbazepine. Tiagabine appeared more effective at higher doses. Side effects were predominately central nervous system-related, the most common being dizziness. For optimal results, tiagabine should be initiated at low doses and titrated slowly. This observational study has demonstrated tiagabine to be effective and safe in patients with refractory epilepsy.

The effect of antiepileptic drugs on visual performance

Visual disturbances are a common side-effect of many antiepileptic drugs. Non-specific retino- and neurotoxic visual abnormalities, that are often reported with over-dosage and prolonged AED use, include diplopia, blurred vision and nystagmus. Some anticonvulsants are associated with specific visual problems that may be related to the mechanistic properties of the drug, and occur even when the drugs are administered within the recommended daily dose. Vigabatrin, a GABA-transaminase inhibitor, has been associated with bilateral concentric visual field loss, electrophysiological changes, central visual function deficits including reduced contrast sensitivity and abnormal colour perception, and morphological alterations of the fundus and retina. Topiramate, a drug that enhances GABAergic transmission, has been associated with cases of acute closed angle glaucoma, while tiagabine, a GABA uptake inhibitor, has been investigated for a potential GABAergic effect on the visual field. Only mild neurotoxic effects have been identified for patients treated with gabapentin, a drug designed as a cyclic analogue of GABA but exhibiting an unknown mechanism while carbamazepine, an inhibitor of voltage-dependent sodium channels, has been linked with abnormal colour perception and reduced contrast sensitivity. The following review outlines the visual disturbances associated with some of the most commonly prescribed anticonvulsants. For each drug, the ocular site of potential damage and the likely mechanism responsible for the adverse visual effects is described.

Complex partial seizures and depression

A long-recognized association exists between epilepsy and affective disturbance, especially depression. People with complex partial seizures that result from temporal lobe seizure foci are highly vulnerable to psychiatric disorders. Accurate diagnosis of such disorders is an important key to treatment. Interictal depression or dysphoria is the most clinically significant problem of this type. Pharmacotherapeutic treatments that have positive effects in other types of depressive illness are also effective for depression associated with epilepsy. Electroconvulsive therapy is helpful to some patients with depression that is refractory to drug treatment or psychotherapy. Surgical resection of seizure foci may lead to psychiatric improvement for some individuals, but can also have psychiatric complications.

Depression in children and adolescents with epilepsy

Depression in children and adolescents with epilepsy is a common but often unrecognized disorder. Both epilepsy and depression are characterized by a chronic course and poor long-term psychosocial outcome. The risk of suicide is even greater in depressed youth with epilepsy than in the general youth population. Educating parents about mood disorders may allow them to be more receptive to psychiatric treatment for their child or themselves. Epidemiological and clinical data on depression in children/adolescents with epilepsy are presented. Seizure-related and general risk factors for the development of depression in youth with epilepsy are reviewed. General guidelines for diagnosis and treatment of depression in children and adolescents are discussed. The early identification and treatment of childhood-onset depression is an important clinical task for all pediatric specialists. Safe and effective multimodal treatment approaches are available.

Clinical and EEG findings in six patients with altered mental status receiving tiagabine therapy

Tiagabine (TGB), a novel GABA reuptake inhibitor antiepileptic drug, has been reported to induce nonconvulsive status epilepticus (NCSE) in patients with generalized or partial onset seizures. We describe six patients with refractory partial epilepsy treated with add-on TGB. They developed acute intermittent or progressive chronic confusion associated with diffuse slowing of the electroencephalogram (EEG), shortly after an increase in dose of TGB. This remitted in each situation after reduction of the daily dose. The possibility of nonconvulsive status epilepticus or toxic encephalopathy is discussed.

Anti-epileptic drugs in pregnancy: current safety and other issues

Women with epilepsy of child-bearing years have their own considerations, which must be taken into account if management of their epilepsy is to be optimised. The main issues to consider include the effects of: female hormones on seizure control, anti-epileptic drugs (AEDs) on hormonal methods of contraception, epilepsy and AEDs on fertility, epilepsy and AEDs on pregnancy itself, pregnancy on AEDs and seizure control and epilepsy, seizures and AEDs on the developing embryo/fetus. Whereas previous studies have concentrated on the increased risk of major congenital malformations from prenatal AED exposure, the effects on cognitive and behavioural development are increasingly being explored. This article looks at the evidence currently available for all of the above issues, taking into account the increased number of AEDs which are now available.

Tiagabine in treatment refractory bipolar disorder: a clinical case series

OBJECTIVES

Anticonvulsants have provided major treatment advances for patients with bipolar disorder. Many of these drugs, including several with proven efficacy in bipolar mania or depression, enhance the activity of the gamma-amino butyric acid (GABA) neurotransmitter system. A new anticonvulsant, tiagabine, has selective GABAergic activity and is approved for patients with partial epilepsy. Few reports of its potential effectiveness in bipolar disorder, however, have been published. We sought to evaluate the effectiveness of tiagabine added to ongoing medication regimens in patients with bipolar disorder inadequately responsive to or intolerant of usual treatments.

METHODS

Seventeen treatment-refractory patients participating in the Stanley Foundation Bipolar Network (SFBN) long-term follow-up study were offered open treatment with add-on tiagabine after discussion of the risks, benefits, other treatment options and giving informed consent. Patients' clinical symptoms and somatic complaints were closely monitored with SFBN longitudinal and cross-sectional ratings. Four patients discontinued low-dose tiagabine prior to the second visit and were excluded from data analysis.

RESULTS

Thirteen patients received a mean of 38 days of treatment at a mean dose of 8.7 mg/day of tiagabine. On the Clinical Global Impression Scale for Bipolar Disorder Overall category, three (23%) patients showed much or very much improvement and 10 (77%) patients showed no change or worsening. Three significant adverse events were noted, including two presumptive seizures.

CONCLUSIONS

Open add-on tiagabine for treatment-refractory patients with bipolar disorder demonstrated limited efficacy with the majority of patients showing no change or worsening of clinical symptoms. In addition, patients experienced serious side-effects attributed as likely due to the medication, which resolved without lasting consequence when tiagabine was discontinued.

Mood disorders in patients with epilepsy: epidemiology and management

Patients with epilepsy are at high risk for depression because of an incompletely understood combination of factors that may be both psychosocial and neurological. Interictal depression in patients with epilepsy is an undertreated condition, in part because of concern regarding drug interactions and the risk of exacerbating seizures with antidepressant treatment. Bipolar disorder is not described as occurring with a higher than expected frequency in the population with epilepsy, but high rates of depression and suicide are well recognised, highlighting the need for more emphasis on antidepressive treatment in this group of at-risk patients. Neurological factors, including site and lateralisation of seizure focus, may be important for the development of depression, with left-sided seizure foci having a higher association with depressive symptoms. Forced normalisation may be a factor in the paradoxical onset of depression in patients with epilepsy whose seizures suddenly become well controlled by anti-seizure treatment. Lowering of folic acid levels by some antiepileptic drugs (AEDs) may also influence the expression of depression in patients with epilepsy. New AEDs continue to emerge as beneficial treatments themselves for mood disorders, with lamotrigine, gabapentin and, to a lesser extent, topiramate having clinical trials data to support their use in patients with bipolar disease. Similar positive data are available for vagal nerve stimulation. Mood effects of AEDs can be complicated, however, as many of these drugs (e.g. tiagabine) have also been reported to cause depression as an adverse effect. Electroconvulsive therapy in depressed patients with epilepsy requires special consideration. The selective serotonin reuptake inhibitors (SSRIs) and antidepressants that act at multiple receptors (e.g. nefazodone, venlafaxine) are the most appropriate treatments for depressed patients with epilepsy. Among these agents, citalopram has a low risk of interactions with AEDs. Bupropion, clomipramine and maprotiline are associated with a greater risk of seizures compared with other antidepressants and consequently should be used with caution in the treatment of depression in patients with epilepsy.

Tiagabine-related non-convulsive status epilepticus in partial epilepsy: three case reports and a review of the literature

There have been several recent reports of non-convulsive status epilepticus during tiagabine therapy in patients with partial epilepsy. We report three cases where elevation of tiagabine dosage was followed by electroclinical features, or electroencephalographic features without clinical signs, of non-convulsive status epilepticus. Administration of clonazepam and/or discontinuation to tiagabine lead to complete remission. In one case after re-exhibition of tiagabine the EEG again showed rhythmic delta waves. We review the other cases reported so far and discuss the different pathophysiological hypotheses about the association in the light of new experimental data.

Treating epilepsy in the elderly: safety considerations

The incidence of epilepsy increases with advancing age. Epilepsy in the elderly has different aetiologies from that in younger populations, cerebrovascular disease being the most common condition associated with seizures. Partial seizures are the predominant seizure type in older patients. A diagnosis of epilepsy in the elderly is based mainly on the history and is frequently delayed. In addition, seizure imitators are especially frequent. In many cases ancillary tests for diagnosis may show normal age-related variants, sometimes making results difficult to interpret. Treating epilepsy in the elderly is problematic due to a number of issues that relate to age and comorbidity. The physical changes associated with increasing age frequently lead to changes in the pharmacokinetics of many anticonvulsants. The treatment of epilepsy in the elderly is also complicated by the existence of other diseases that might affect the metabolism or excretion of anticonvulsants and the presence of concomitant medications that might interact with them. Moreover, specific trials of anticonvulsants in the aged population are scarce. General guidelines for treatment include starting at lower doses, slowing the titration schedule, individualising the choice of anticonvulsant to the characteristics of the patient, avoiding anticonvulsants with important cognitive or sedative adverse effects, and where possible, treating with monotherapy.

Epilepsy in the elderly: the use of tiagabine

The incidence of epilepsy increases sharply in patients older than 60 years. There is a clear need for clinical trials designed specifically for this age group, as elderly patients differ from younger patients with epilepsy with respect to seizure etiology, coexisting diseases, concomitant drug therapy, and drug disposition. The new antiepileptic drugs (AEDs) are often associated with fewer side effects than are the traditional AEDs and may be particularly useful in the elderly. The pharmacokinetics of tiagabine (TGB) are not significantly modified in elderly patients, although elimination is more rapid in the presence of enzyme-inducing AEDs. Efficacy and tolerability data on TGB in elderly patients is currently limited, and a formal trial of TGB monotherapy in this age group is needed.

Tiagabine in clinical practice

Among the newly introduced antiepileptic drugs (AEDs), tiagabine (TGB) stands out as a compound with a well-understood and documented mechanism of action. It is a lipophilic derivative of nipecotic acid that blocks gamma-aminobutyric acid (GABA) reuptake by inhibition of the GAT-1 transportation system, and that has no other significant pharmacodynamic effect. The relationship between intake and blood levels is linear. Usual daily maintenance doses range from 20 to 50 mg. It is completely absorbed by the gastrointestinal tract, and its half-life is approximately 7-9 h. TGB is sensitive to enzyme induction: when coprescribed with enzyme-inducing AEDs, its half-life is shortened to 2-3 h, whereas the daily dosage has to be increased into the upper range. It should be given 3 times per day. Placebo-controlled, double-blind, add-on studies conducted in patients with drug-resistant focal epilepsies have demonstrated its efficacy and overall safety. The clinical benefits appear to persist over time. Data on its use in monotherapy are scanty. The efficacy and tolerability of TGB in the pediatric age still remain to be investigated adequately. In daily practice, TGB appears to be a safe drug, but mild to moderate side effects are frequently seen, especially during titration: these include dizziness and fatigue, and are clearly abated when the drug is absorbed during meals. Titration should be especially slow, no faster than 5 mg weekly. Clinicians also should beware of the possible occurrence of confusion, which may be misdiagnosed as absence status, a short-lasting, quickly reversible central nervous system-related side effect that appears to be correlated with the peak plasma concentrations of TGB. Particularly beneficial indications for TGB and/or AED associations including TGB have not been pointed out, but there is a hint that it works best in temporal lobe epilepsies.

Long-term safety of tiagabine

Tiagabine (TGB) is now registered in >20 countries, and the total number of treated patients approaches 90,000. Short-term safety data were derived mainly from five placebo-controlled, add-on studies in adults with therapy-resistant partial epilepsy, and two conversion to TGB monotherapy studies. Central nervous system (CNS)-related adverse effects, most frequently dizziness, were common with TGB treatment during the titration period; the risk became similar to placebo rates during fixed-dose periods. Other adverse events that were more frequent in TGB- than in placebo-treated patients were asthenia, nervousness, tremor, concentration difficulties, depressive mood, and language problems. TGB doses should be titrated slowly and taken with food to avoid rapid increases in plasma concentrations, thus minimizing the risks of adverse events. Overall, >2,500 patients have been exposed to TGB during clinical trials, with 1,274 patients treated >12 months, the majority of whom received TGB 24-60 mg/day. No idiosyncratic reactions have been linked to the use of TGB, and no abnormalities in hematology or common chemistry values were reported. In all the epilepsy studies combined, 21% of patients discontinued treatment because of adverse events, usually during the first 6 months of treatment. No adverse effects on cognitive abilities were detected when the neuropsychological effects of TGB add-on therapy and monotherapy were evaluated. TGB does not appear to cause an excess risk of psychosis or increase the incidence of status epilepticus or spike/wave discharges. No evidence of a relationship between visual field constriction and TGB treatment was found in a study of 15 patients converted to TGB monotherapy (mean dose, 22 mg/day; mean duration, 2.5 years) who had a full ophthalmologic evaluation. In conclusion, the characteristics of TGB in the management of partial epilepsy are enhanced by its favorable side-effect profile in the cognitive area.

Transient dystonias in three patients treated with tiagabine

PURPOSE

Tiagabine (TGB) is a new antiepileptic drug (AED) with gamma-aminobutyric acid (GABA)ergic mechanism of action. GABAergic compounds may influence the extrapyramidal system, probably via modulation of dopaminergic nigrostriatal neurons. A well-known side effect of TGB is probably dose-related extrapyramidal tremor. To our knowledge, acute dystonias associated with TGB treatment have yet to be described.

METHODS

Three patients with transient acute dystonic reactions while taking TGB as add-on therapy with carbamazepine (CBZ) are presented. The focal limb dystonia in one case, an oromandibular dystonia in second, and writer's cramp in third one were observed.

RESULTS

In all cases dystonic movements resolved spontaneously without discontinuation of TGB therapy and without any concomitant treatment.

CONCLUSIONS

Tiagabine may cause various mild extrapyramidal side effects. All three cases reported were diagnosed with transient possibly drug-related dystonia after increase in TGB dose. It remain unclear whether dystonic movements are specific for patients treated with TGB/CBZ bitherapy.

Pharmacologic management of epilepsy in the elderly

OBJECTIVE

To review the epidemiology and pharmacologic management of epilepsy in elderly patients.

DATA SOURCES

Controlled trials, case studies, and review articles identified via MEDLINE using the search terms epilepsy, seizures, elderly, phenobarbital, primidone, phenytoin, carbamazepine, valproic acid, felbamate, gabapentin, lamotrigine, topiramate, tiagabine, levetiracetam, oxcarbazepine, and zonisamide. Recently published standard textbooks on epilepsy were also consulted.

DATA SYNTHESIS

Epilepsy is a common neurologic disorder in the elderly. Cerebrovascular and neurodegenerative diseases are the most common causes of new-onset seizures in these patients. Alterations in protein binding, distribution, elimination, and increased sensitivity to the pharmacodynamic effects of antiepileptic drugs (AEDs) are relatively frequent, and these factors should be assessed at the initiation, and during adjustment, of treatment. Drug-drug interactions are also an important issue in elderly patients, because multiple drug use is common and AEDs are susceptible to many interactions. In addition to understanding age-related changes in the pharmacokinetics and pharmacodynamics of AEDs, clinicians should know the common seizure types in the elderly and the spectrum of AED activity for these seizure types. AEDs with activity against both partial-onset and generalized seizures include felbamate, lamotrigine, levetiracetam, topiramate, valproic acid, and zonisamide. Other AEDs discussed in this review (carbamazepine, gabapentin, phenobarbital, phenytoin, primidone, and tiagabine) are most useful for partial-onset seizures.

CONCLUSION

The provision of safe and effective drug therapy to elderly patients requires an understanding of the unique age-related changes' in the pharmacokinetics and pharmacodynamics of AEDs as well as an appreciation of common seizure types and the drugs that are effective for the specific types seen in the elderly.

Efficacy, pharmacology, and adverse effects of antiepileptic drugs

This article discusses the factors involved in the appropriate selection of anticonvulsant medications. The clinical use of commonly used traditional antiepileptic drugs and the newly marketed antiepileptic drugs is discussed. This includes the specific indications for use, adverse effects, and dosing of each drug. Drug interactions, mechanisms of action, and pharmacological properties of each drug is also reviewed.

Status epilepticus and tiagabine therapy: review of safety data and epidemiologic comparisons

PURPOSE

To determine whether an increased risk of status epilepticus (SE) and complex partial status epilepticus (CPSE) is associated with tiagabine (TGB) therapy.

METHODS

Thirteen cases in which an EEG, performed on patients with altered mental status taking TGB, was reported to demonstrate spike-and-wave discharges (SWDs) were reviewed by a panel of experts. In addition, all cases of suspected SE from TGB clinical trials were reviewed. The occurrence of SE in four epidemiologic cohorts from Rochester, Minnesota, Turku, Finland, Bronx, New York, and New Haven, Connecticut was analyzed as an external comparison.

RESULTS

Review of the 13 cases with reported SWDs found that the majority had had prior EEGs with similar findings, and only three were thought to have electrographic evidence of SE. There was no difference in the frequency of SE or CPSE in the placebo-controlled clinical trials between the TGB-treated (1.0% SE, 0.8% CPSE) and placebo-treated (1.5% SE, 1.5% CPSE) groups. The 5% frequency of SE and 3% frequency of CPSE in the TGB-treated patients in the long-term safety studies, which included 2,248 patients, were very similar to the rates of occurrence of SE and CPSE in the four external cohorts. The major risk factor for the occurrence of SE and CPSE in all groups was a prior episode of SE (p < 0.0001).

CONCLUSIONS

Over a 3-year period, SE will occur in 5-10% of patients with epilepsy not in remission. At highest risk are those who have had a prior episode of SE. Treatment with TGB in recommended doses does not increase the risk of SE in patients with partial seizures.

Therapeutic safety monitoring: what to look for and when to look for it

This review focuses on the safety problems associated with antiepileptic drugs (AEDs) as revealed by laboratory testing and clinical examination. There are two classes of side effects: (a) common and mild and (b) rare and severe. Allergic reactions to AEDs are common and usually mild. However, on rare occasions, they can progress to more severe cutaneous disorders, including Stevens-Johnson syndrome and toxic epidermal necrolysis. Severe allergic reactions to AEDs range from immune responses with fever to multiorgan dysfunction. Allergic rashes may be genetically or immunologically determined. Laboratory abnormalities produced by AEDs are common and mild, and include hepatic enzyme elevation associated with phenytoin and mild elevation in ammonia associated with valproate. Serious, although rare, idiosyncratic side effects, such as aplastic anemia, hepatotoxicity, and thrombocytopenia, have also occurred with AEDs. These reactions are largely confined to the "classic" AEDs. With the exception of felbamate, AEDs approved in the past decade have not been plagued by severe idiosyncratic reactions. Subtle endocrine abnormalities, including variations in thyroid function tests and bone metabolism, and the often subclinical effects on peripheral nerve conduction produced by phenytoin and carbamazepine, are also examined.

Pharmacology and clinical experience with tiagabine

Tiagabine (TGB), a recently approved anti-epileptic drug (AED), has a specific and unique mechanism of action involving the inhibition of gamma-aminobutyric acid (GABA) re-uptake into neurones and glia. TGB is potent and has linear and predictable pharmacokinetics. It does not induce or inhibit hepatic metabolism and has no clinically significant effects on the serum concentrations of other AEDs or commonly used non-AEDs. Double-blind, placebo-controlled studies in primarily hepatic enzyme-induced patients showed that TGB 30 - 56 mg/day is an effective add-on treatment for all subtypes of partial seizures. The most common adverse effects in the trials were dizziness, asthenia (weakness), somnolence, accidental injury, infection, headache, nausea and nervousness. These side effects were usually mild to moderate in severity and generally did not require medical intervention. Long-term safety studies show continued efficacy of TGB over time and no evidence of tolerance for efficacy. Open studies confirm that patients with medically refractory partial epilepsy can be successfully converted to TGB monotherapy and that TGB may be effective for other seizure types, such as infantile spasms.

Progress report on new antiepileptic drugs: a summary of the Fifth Eilat Conference (EILAT V)

The Fifth Eilat Conference on New Antiepileptic Drugs (AEDs) took place at the Dan Hotel, Eilat, Israel, 25-29 June 2000. Basic scientists, clinical pharmacologists and neurologists from 20 countries attended the conference, whose main themes included recognition of unexpected adverse effects, new indications of AEDs, and patient-tailored AED therapy. According to tradition, the central part of the conference was devoted to a review of AEDs in development, as well to updates on AEDs that have been marketed in recent years. This article summarizes the information presented on drugs in preclinical and clinical development, including AWD 131-138, DP-valproate, harkoseride, LY300164, NPS 1776, NW 1015, pregabalin, remacemide, retigabine, rufinamide and valrocemide. The potential value of an innovative strategy, porcine embryonic GABAergic cell transplants, is also discussed. Finally, updates on felbamate, fosphenytoin, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, tiagabine, topiramate, vigabatrin, zonisamide, and the antiepileptic vagal stimulator device are presented.

Frontal nonconvulsive status epilepticus associated with high-dose tiagabine therapy in a child with familial bilateral perisylvian polymicrogyria

PURPOSE

Antiepileptic drugs are known to exacerbate absence and myoclonic seizures, especially in patients with idiopathic generalized epilepsies. Exacerbation of nonconvulsive generalized seizures in patients with partial epilepsy is less common. Recently, however, a number of cases of putative generalized nonconvulsive status epilepticus (NCSE) or NCSE without further specification have been reported in patients with chronic partial epilepsy treated with the gamma-aminobutyric acid reuptake inhibitor tiagabine. Although complex partial status epilepticus during tiagabine therapy has also been reported, possible precipitation of NCSE specifically associated with frontal lobe discharges does not appear to have been recognized. In this communication, we describe the case of a boy with familial bilateral perisylvian polymicrogyria who developed frontal NCSE after being stabilized on high-dose tiagabine

METHODS

A 12-year-old boy with familial bilateral perisylvian polymicrogyria, mental retardation, and refractory partial seizures was administered tiagabine in addition to sodium valproate. The tiagabine dosage was increased gradually up to 10 mg t.i.d. (1 mg/kg per day), resulting in complete seizure control.

RESULTS

After 1 week on maintenance treatment, seizures were completely controlled, but the child developed hypoactivity, decreased reactivity, and affective detachment. An EEG recording revealed subcontinuous sharp-wave discharges with irregular runs of atypical spike-wave complexes over the anterior regions of both hemispheres, consistent with a diagnosis of frontal NCSE. A reduction in tiagabine dosage to 15 mg/day led to complete regression of the behavioral and affective changes and to disappearance of the subcontinuous EEG discharges.

CONCLUSIONS

Although tiagabine-induced NCSE has been described previously, particularly in patients with preexisting spike-wave abnormalities, this is the first report that identifies its potential role in the precipitation of frontal NCSE.

Tiagabine in the treatment of epilepsy--a clinical review with a guide for the prescribing physician

Tiagabine is currently recommended mainly as add-on therapy in adults and children above 12 years with partial epilepsy not satisfactorily controlled with other antiepileptic drugs. Based on available evidence and our clinical experience, tiagabine should be used preferably in patients sharing one or more of the following additional features, (i) a history of drug-induced cutaneous adverse events; (ii) mild to moderate epilepsy allowing for a slow titration and gradual onset of anticonvulsant action over a few weeks; (iii) patients for whom it is particularly important to avoid a deterioration in cognitive performance; and, (iv) patients who failed to respond to previous treatment with sodium channel blocker agents as they may particularly benefit from the introduction of tiagabine, due to its GABAergic mechanism of action. Tiagabine can also be used successfully in other patients with refractory partial epilepsy. Tiagabine is not indicated for patients with generalized or unclassified epilepsies and for patients with severely impaired liver function.