Adjunctive zonisamide therapy in the long-term treatment of children with partial epilepsy: results of an open-label extension study of a phase III, randomized, double-blind, placebo-controlled trial

Zonisamide: A Comprehensive, Updated Review for the Clinician

Purpose of Review

Zonisamide (ZNS) was first approved in the United States in 2000 for the adjunctive treatment of patients aged 16 years or older with partial (focal) seizures. Although ZNS has been proven to treat multiple seizure types, it has been largely underutilized in US clinical practice.

Recent Findings

Published literature demonstrated that antiseizure medications (ASMs) acting on Na+ and Ca2+ channels may add beneficial effects in many seizure types by reducing seizure frequency and leading to overall improvements. In addition, effects of ZNS may lead to clinical improvements in Parkinson disease, alcohol and sleep disorders, pain, and migraine. ZNS is available in multiple formulations and is a safe and effective, broad spectrum ASM.

Summary

The purpose of this review was to provide an update to what is known about the efficacy of ZNS and where it shows benefits in the treatment of patients with epilepsy and other CNS disorders through its many unique mechanisms of action.

Long-term safety and efficacy of adjunctive brivaracetam in pediatric patients with epilepsy: An open-label, follow-up trial

OBJECTIVE

This study was undertaken to evaluate the long-term safety, tolerability, and efficacy of adjunctive brivaracetam (BRV) treatment in pediatric patients with epilepsy.

METHODS

A phase 3, open-label, multicenter, long-term follow-up trial (N01266; NCT01364597) was conducted on patients (aged 1 month to <17 years at core trial entry; direct enrollers aged 4 to <17 years) treated with BRV. Outcomes included treatment-emergent adverse events (TEAEs), behavior assessments (Achenbach Child Behavior Checklist [CBCL], Behavior Rating Inventory of Executive Function [BRIEF]/BRIEF-Preschool version [BRIEF-P]), and efficacy outcomes (percent change in focal seizure frequency, 50% responder rate for all seizure types for patient subgroups <2 years and ≥2 years of age using daily record card data).

RESULTS

Of 257 patients with ≥1 dose of BRV (141 [54.9%] male; mean age = 8.0 years [SD = 4.5]), 36 patients were <2 years of age, and 72.0% of patients had a history of focal seizures. Mean BRV exposure was 3.2 patient-years. At least one TEAE occurred in 93.4% patients, and 32.3% had serious TEAEs. Seven patients died during the trial; no deaths were considered treatment-related. Patients ≥2 years of age had a median decrease in 28-day adjusted focal seizure frequency of 62.9%, and 50.9% had a ≥50% response in all seizures. Patients <2 years of age had a median decrease in 28-day adjusted focal seizure frequency of 96.9%, and 68.2% had a ≥50% response in all seizures. Kaplan-Meier estimated treatment retention was 72.7%, 64.5%, 57.8%, 53.3%, 50.1%, and 44.8% at 1, 2, 3, 4, 5, and 6 years, respectively. Mean changes (baseline to last evaluation) for all Achenbach CBCL and BRIEF-P/BRIEF subscale scores were negative, reflecting stability/slight improvement.

SIGNIFICANCE

Long-term adjunctive BRV treatment was generally well tolerated and efficacious in reducing seizure frequency, and had high retention rates, with generally stable cognitive/behavioral scores in pediatric patients with epilepsy.

Impact of Antiseizure Medications on Appetite and Weight in Children

There are numerous potential factors that may affect growth in children with epilepsy, and these must be evaluated in any child with appetite and weight concerns. Antiseizure medications (ASMs) have potential adverse effects, and many may affect appetite, thus impacting normal growth and weight gain. The aim of this review is to focus on the impact of both epilepsy and ASMs on appetite and weight in children. We systematically reviewed studies using Medline assessing the impact of ASMs on appetite and weight in children. Eligible studies included randomized controlled trials and open-label studies (open-label extension and interventional) that targeted or included the pediatric population (0-18 years of age). Each study was classified using the American Academy of Neurology (AAN) Classification of Evidence for Therapeutic Studies, and the level of evidence for impact on appetite and weight in children was graded. ASMs associated with decreased appetite and/or weight loss include fenfluramine, topiramate, zonisamide, felbamate, rufinamide, stiripentol, cannabidiol, brivaracetam and ethosuximide; ASMs with minimal impact on weight and appetite in children include oxcarbazepine, eslicarbazepine, lamotrigine, levetiracetam, lacosamide, carbamazepine, vigabatrin and clobazam. The ASM most robustly associated with increased appetite and/or weight gain is valproic acid; however, both pregabalin and perampanel may also lead to modest weight gain or increased appetite in children. Certain ASMs may impact both appetite and weight, which may lead to increased morbidity of the underlying disease and impaired adherence to the treatment regimen.

Cost-effectiveness of perampanel as an adjunctive treatment for uncontrolled focal seizures in pediatric patients: a Chinese perspective

Background

The incidence of epilepsy is 41-187 per 100,000 person-year in children. The health care costs for children with uncontrolled epilepsy is a huge burden. Perampanel (PER) was effective, safety and well-tolerated as add-on therapy in pediatric patients aged 4 to <12 years with uncontrolled focal seizures. However, there is still limited evidence on cost-effectiveness of PER in pediatric patients. We aimed to evaluate the cost-effectiveness of PER as an add-on therapy for pediatric patients with uncontrolled focal seizures.

Methods

A Markov model was established to conduct an analysis from the perspective of the Chinese health system and society. The incremental cost-effectiveness ratio (ICER) of patients using PER and conventional therapy versus patients using conventional therapy alone were estimated and compared. The transition probability of the response level, health state utility values, and costs were derived from clinical trials and the literature. Costs, including medical, drug, transportation and indirect costs, were calculated. We performed 1-way sensitivity analyses and probabilistic sensitivity analyses. A subgroup analysis of different ages was also conducted.

Results

The base-case analysis indicated that compared to maintaining conventional therapy, adding PER as an adjuvant drug therapy had an increased cost of $3,449.85 over 5 years, with an incremental quality-adjusted life years (QALY) value of 0.40, resulting in an ICER of $8,582.58 per additional QALY. The health state utility value had the greatest effect on the ICER. The probabilistic sensitivity analyses showed that the probability of PER being cost-effective was 76.72% at a willingness-to-pay of $11,293/QALY. The ICER of the subgroup ranged from $7,167.95/QALY to $19,710.96/QALY.

Conclusions

Our study demonstrated that PER is a cost-effective add-on therapy for pediatric patients.

Clinical Trial Design for Disease-Modifying Therapies for Genetic Epilepsies

Although trials with anti-seizure medications (ASMs) have not shown clear anti-epileptogenic or disease-modifying activity in humans to date, rapid advancements in genomic technology and emerging gene-mediated and gene replacement options offer hope for the successful development of disease-modifying therapies (DMTs) for genetic epilepsies. In fact, more than 26 potential DMTs are in various stages of preclinical and/or clinical development for genetic syndromes associated with epilepsy. The scope of disease-modification includes but is not limited to effects on the underlying pathophysiology, the condition's natural history, epilepsy severity, developmental achievement, function, behavior, sleep, and quality of life. While conventional regulatory clinical trials for epilepsy therapeutics have historically focused on seizure reduction, similarly designed trials may prove ill-equipped to identify these broader disease-modifying benefits. As we look forward to this pipeline of DMTs, focused consideration should be given to the challenges they pose to conventional clinical trial designs for epilepsy therapeutics. Just as DMTs promise to fundamentally alter how we approach the care of patients with genetic epilepsy syndromes, DMTs likewise challenge how we traditionally construct and measure the success of clinical trials. In the following, we briefly review the historical and preclinical frameworks for DMT development for genetic epilepsies and explore the many novel challenges posed for such trials, including the choice of suitable outcome measures, trial structure, timing and duration of treatment, feasible follow-up period, varying safety profile, and ethical concerns.

Long-term safety, efficacy, and quality of life during adjunctive brivaracetam treatment in patients with uncontrolled epilepsy: An open-label follow-up trial

OBJECTIVES

The primary objective of this long-term follow-up (LTFU) trial was to evaluate the long-term safety and tolerability of brivaracetam (BRV). The secondary objective was to evaluate the maintenance of efficacy of BRV (including quality of life) over time.

METHODS

This open-label, multicenter, flexible-dose trial (N01379 [NCT01339559]) was conducted in adults (≥16 years) with focal or generalized-onset seizures, who had participated in a placebo (PBO)-controlled trial of adjunctive BRV (N01258: NCT01405508 or N01358: NCT01261325).

RESULTS

Seven hundred and sixty-six patients received BRV in this LTFU trial (753 had focal seizures and 13 had generalized-onset seizures). Kaplan-Meier-estimated retention was 71.9% at 12 months, and 53.7% at 36 months. Treatment-emergent adverse events (TEAEs) were reported by 643 (83.9%) patients, most commonly headache (104 [13.6%] patients) and dizziness (100 [13.1%] patients). Two hundred and fifty-seven (33.6%) patients had drug-related TEAEs, most commonly somnolence (49 [6.4%] patients) and dizziness (41 [5.4%] patients). Permanent discontinuation of BRV due to TEAEs occurred in 91 (11.9%) patients. Patients with focal seizures had a median percentage reduction in focal seizure frequency of 52.0% and 51.7% were 50% responders (sustained over time); 26.0% were seizurefree for 6 months, and 17.9% were seizurefree for 12 months. 42.4% of patients at 12 months and 46.8% at 24 months had clinically meaningful improvements in Patient Weighted Quality of Life in Epilepsy Questionnaire 31 total score.

CONCLUSIONS

In this select group of patients who entered the LTFU trial, BRV was generally safe and well tolerated. Results indicate the long-term efficacy of BRV in patients with focal seizures.

Neurocognitive Effects of Antiseizure Medications in Children and Adolescents with Epilepsy

Impairments in cognition are common in epilepsy and may be caused or exacerbated by antiseizure medications (ASMs). Positive effects on cognition may also be seen with some ASMs. Cognitive outcomes are of particular concern in children who may be at an increased risk of cognitive adverse effects of treatment. A comprehensive literature search was conducted in PubMed in order to evaluate the evidence for cognitive changes associated with treatment with ASMs in paediatric epilepsy patients. The ASMs considered were those in the current edition of the British National Formulary (BNF). For most ASMs, remarkably few studies providing robust data on cognitive effects in paediatric patients were identified. The available evidence suggests cognitive impairments may be associated with treatment with phenobarbital. Topiramate and phenytoin are also associated with negative effects on cognition, in particular word-finding difficulties and other language deficits with topiramate, but there are few data available specifically on children. Lamotrigine, levetiracetam and fenfluramine are associated with improvements in some cognitive domains, although it is unclear whether these effects are directly attributable to the medications or are a result of improvements in seizures. Neutral effects on cognition (no substantial evidence of worsening) were suggested for carbamazepine, everolimus, lacosamide, oxcarbazepine, perampanel and valproate. There is limited data for cannabidiol, clobazam, eslicarbazepine acetate, ethosuximide, rufinamide, vigabatrin and zonisamide, although the available evidence suggests these drugs are not associated with severe cognitive impairment. There was too little information to reach conclusions about the effects of brivaracetam, felbamate, gabapentin, pregabalin, retigabine, stiripentol or tiagabine.

Safety and tolerability of adjunctive brivaracetam in children with focal seizures: Interim analysis of pooled data from two open-label trials

OBJECTIVE

To evaluate long-term safety and tolerability of adjunctive brivaracetam (BRV) in children with epilepsy.

METHODS

This was an interim analysis (cut-off March 15, 2017) of pooled data from two open-label, single-arm, multicentre trials. N01263 (NCT00422422) was a 3-week trial of BRV 0.8-4 mg/kg/day in patients (1 month-<16 years) with epilepsy. Patients who completed this trial could continue into a long-term follow-up trial (N01266, NCT01364597) which also directly enrolled patients (4-<17 years) with focal seizures. After dose-escalation, patients received BRV 1-5 mg/kg/day (maximum 200 mg/day) during long-term evaluation. Data are reported for patients aged 4 to <16 years with focal seizures.

RESULTS

The safety set comprised 149 patients: 34 from the initial trial (26 entered long-term trial) and 115 directly enrolled into the long-term trial. At the cut-off, 90 patients were receiving BRV (total exposure: 299.4 patient-years). Treatment-emergent adverse events (TEAEs) were reported by 140/149 (94.0%) patients, most commonly (≥20%) nasopharyngitis (24.8%), pharyngitis (22.1%), convulsion (21.5%), and pyrexia (20.1%). TEAEs considered drug-related by the investigator were reported by 56/149 (37.6%) patients, most commonly somnolence (6.0%). Two patients died; neither death was considered related to BRV. Mean changes from baseline in child behaviour rating scales were small; most patients remained in their baseline category.

CONCLUSION

In this pooled analysis of two open-label trials including long-term data, adjunctive BRV was generally well tolerated in children aged 4 to <16 years with focal seizures. These findings supported approval of BRV as a new therapy option for children aged ≥4 years with focal seizures.

Pharmacotherapy for Focal Seizures in Children and Adolescents

Focal-onset seizures are among the most common forms of seizures in children and adolescents and can be caused by a wide diversity of acquired or genetic etiologies. Despite the increasing array of antiseizure drugs available, treatment of focal-onset seizures in this population remains problematic, with as many as one-third of children having seizures refractory to medications. This review discusses contemporary concepts in focal seizure classification and pathophysiology and describes the antiseizure medications most commonly chosen for this age group. As antiseizure drug efficacy is comparable in children and adults, here we focus on pharmacokinetic aspects, drug-drug interactions, and side effect profiles. Finally, we provide some suggestions for choosing the optimal medication for the appropriate patient.

[Clinical experience of using zonisamide in structural focal epilepsy in children with cerebral palsy]

AIM

To evaluate the efficacy and safety of zonisamide as an add-on therapy in structural focal epilepsy in children with cerebral palsy (CP).

MATERIAL AND METHODS

Sixty-four patients (36 boys and 28 girls) with spastic CP and structural focal epilepsy with refractory seizures were followed up. Patients received zonisamide in a dose of 6-8.8 mg/kg/day for ≥6 months. Treatment efficacy was assessed by the reduction of seizures depending on CP form, type of epileptic seizures, combination of zonisamide with other drugs and adverse-effects.

RESULTS AND CONCLUSION

A reduction of seizures by ≥50% was identified in 60.9% of children, 10.9% showed a better recovery. The best efficacy (35.9%) was demonstrated in the treatment of generalized seizures with focal onset and in the combination with levetiracetam (35.9%). Adverse effects of mild to moderate severity were noted in 26.5% of children. The treatment was discontinued in 7.8%. Therefore, zonisamide is an effective treatment for refractory structural focal epilepsy in children with CP and comorbid pathology, which reduces the frequency of seizures without severe side-effects.

Safety and tolerability profile of new antiepileptic drug treatment in children with epilepsy

INTRODUCTION

Treatment of pediatric epilepsy requires a careful evaluation of the safety and tolerability profile of antiepileptic drugs (AEDs) to avoid or minimize as much as possible adverse events (AEs) on various organs, hematological parameters, and growth, pubertal, motor, cognitive and behavioral development.

AREAS COVERED

Treatment-emergent AEs (TEAEs) reported in the literature 2000-2018 regarding second- and third-generation AEDs used in the pediatric age, with exclusion of the neonatal period that exhibits specific peculiarities, have been described on the basis of their frequency, severity/tolerability, and particular association with a given AED.

EXPERT OPINION

Somnolence/sedation and behavioral changes, like irritability and nervousness, are among the most commonly observed TEAEs associated with almost all AEDs. Lamotrigine, Gabapentin, Oxcarbazepine, and Levetiracetam appear to be the best-tolerated AEDs with a ≤2% withdrawal rate, while Tiagabine and Everolimus are discontinued in up to >20% of the patients because of intolerable TEAEs. For some AEDs, literature data are scanty to draw a high-level evidence on their safety and tolerability profile. The reasons are: insufficient population size, short duration of treatments, or lack of controlled trials. A future goal is that of identifying clearer, easier, and more homogeneous methodological strategies to facilitate AED testing in pediatric populations.

Long-term effects of adjunctive perampanel on cognition in adolescents with partial seizures

OBJECTIVE

The aim of this study was to evaluate long-term effects of adjunctive perampanel on cognition, efficacy, growth, safety, and tolerability in adolescents with inadequately controlled partial seizures.

METHODS

Study 235, a multicenter, randomized, double-blind, placebo-controlled, parallel-group, Phase II study with an open-label extension phase (NCT01161524), was primarily designed to assess the effects of adjunctive perampanel on cognition. Patients (aged ≥12 to <18years) had a diagnosis of epilepsy with inadequately controlled partial seizures, with or without secondary generalization, despite receiving 1-3 antiepileptic drugs. During the double-blind phase, adjunctive perampanel or placebo was administered over a 6-week titration period and a 13-week maintenance period up to 12mg/day. During the extension phase, all patients received perampanel. Data from the extension phase are presented here. Study endpoints included change from baseline in Cognitive Drug Research (CDR) measures of cognition, seizure frequency, growth, development, the occurrence of treatment-emergent adverse events (TEAEs), and laboratory values.

RESULTS

A total of 114 patients entered the extension phase (prior double-blind treatment: placebo, n=41; perampanel, n=73). Perampanel had no effect on the CDR system global cognition score, continuity of attention, quality of episodic memory, quality of working memory, or speed of memory but was associated with a significant decline in power of attention at end of treatment compared with baseline (p=0.03). There were no effects on language skills or manual dexterity from baseline to end of treatment. At Weeks 40-52, median reduction in seizure frequency was 74.1%, and 50% responder rate was 66.0%. There were no clinically relevant effects of perampanel on growth or development at end of treatment compared with baseline. Overall, 84.2% of patients experienced at least one TEAE and 70.2% experienced at least one treatment-related TEAE. The most common TEAEs were dizziness (29.8%) and somnolence (19.3%). The TEAEs resulted in the discontinuation of treatment in 6.1% of patients.

CONCLUSIONS

In keeping with the 19-week double-blind phase, long-term adjunctive treatment with perampanel did not have any significant overall effects on the CDR system global cognition score in adolescent patients with inadequately controlled partial seizures. Similar trends were observed across the individual CDR system domains. Adjunctive perampanel showed sustained long-term seizure control and had a safety and tolerability profile similar to that observed in prior clinical studies.

Cognitive and Behavioral Comorbidities: An Unwanted Effect of Antiepileptic Drugs in Children

Epilepsy is one of the most common neurological disorders and, despite optimally chosen and dosed antiepileptic drugs (AEDs), approximately 20%-30% of patients will continue to have seizures. Behavior and cognition are negatively impacted by seizures, but AEDs are also a major contributor to behavioral and cognitive deficits. However, the cognitive and behavioral effect of AEDs in children is insufficiently emphasized in the literature. This review summarizes the cognitive and behavioral effects of AEDs in the pediatric population with the objective of helping pediatricians and pediatric neurologists to select the AEDs with the best profile for their individual patient's needs.

Epilepsy, Antiepileptic Drugs, and Aggression: An Evidence-Based Review

Antiepileptic drugs (AEDs) have many benefits but also many side effects, including aggression, agitation, and irritability, in some patients with epilepsy. This article offers a comprehensive summary of current understanding of aggressive behaviors in patients with epilepsy, including an evidence-based review of aggression during AED treatment. Aggression is seen in a minority of people with epilepsy. It is rarely seizure related but is interictal, sometimes occurring as part of complex psychiatric and behavioral comorbidities, and it is sometimes associated with AED treatment. We review the common neurotransmitter systems and brain regions implicated in both epilepsy and aggression, including the GABA, glutamate, serotonin, dopamine, and noradrenaline systems and the hippocampus, amygdala, prefrontal cortex, anterior cingulate cortex, and temporal lobes. Few controlled clinical studies have used behavioral measures to specifically examine aggression with AEDs, and most evidence comes from adverse event reporting from clinical and observational studies. A systematic approach was used to identify relevant publications, and we present a comprehensive, evidence-based summary of available data surrounding aggression-related behaviors with each of the currently available AEDs in both adults and in children/adolescents with epilepsy. A psychiatric history and history of a propensity toward aggression/anger should routinely be sought from patients, family members, and carers; its presence does not preclude the use of any specific AEDs, but those most likely to be implicated in these behaviors should be used with caution in such cases.

Advancing pharmacologic treatment options for pharmacologic treatment options for children with epilepsy

INTRODUCTION

The pharmacological management of epilepsy is continually modified by the increase in our knowledge about the efficacy and the safety on antiepileptic drugs.

AREAS COVERED

This review covers the published data (2010-2015) on the pharmacological management of epilepsy in children and adolescent. We review the data from the most recent randomized controlled and open-label trials.

EXPERT OPINION

Even if there is an increasing number of antiepileptic drugs approved for focal seizure in children and adolescent with epilepsy, each new approval would be considered as a significant addition to the current therapeutic options. Refractory epilepsy with focal seizure should not be regarded as a single disease but as numerous various patients. Because most of evidence of efficacy is primarily from placebo-controlled trials, there is no evidence to choose a treatment based on efficacy. In case of focal seizure, we explain how possible cognitive impact, mechanisms of action, pharmacologic characteristics and side effect profile are the factors taken into an account to propose a treatment. In case of childhood absence epilepsy, there are evidences showing the ethosuximide should be the first line treatment. Finally, we stress that trials in the pediatric epilepsy syndromes are required to propose better evidence-based pharmacological management.

Zonisamide: Review of Recent Clinical Evidence for Treatment of Epilepsy

Zonisamide is an orally administered antiepileptic drug that was first approved for clinical use in Japan in 1989. Since then, it has been licensed in Korea for a broad spectrum of epilepsies in adults and children, and in the USA for adjunctive therapy of adults with partial seizures, and in Europe for monotherapy of adults with newly diagnosed partial seizures and adjunctive therapy of adults and adolescents and children aged ≥6 years with partial seizures with or without secondary generalization. Zonisamide is a benzisoxazole derivative with a unique chemical structure, predictable dose-dependent pharmacokinetics, and multiple complementary mechanisms of action. Treatment with zonisamide is well tolerated and is not known to be associated with clinically significant drug-drug interactions, including with oral contraceptives or other antiepileptic drugs. There have been >2 million patient-years of experience with zonisamide for treatment of epilepsy, and this drug has International League Against Epilepsy level A evidence for efficacy/effectiveness as initial monotherapy for adults with partial-onset seizures. This review presents the evidence for zonisamide across the spectrum of epilepsy, with emphasis on real-world clinical practice and special populations of patients (children, elderly patients, and women of childbearing age) who are likely to be treated in daily clinical practice.

The safety and long-term efficacy of zonisamide as adjunctive therapy for focal epilepsy

Epilepsy is a chronic disease which affects 1% of the population worldwide. As treatment is required for many years or decades, the long-term efficacy and tolerability of antiepileptic drugs are particularly important. Zonisamide (ZNS) is a second-generation antiepileptic drug with a unique structure and multiple mechanisms of action. Here, recently published long-term outcomes of patient cohorts with focal epilepsy undergoing ZNS treatment are discussed. Whereas ZNS monotherapy maintains similar seizure control efficacy to carbamazepine after 2 years of treatment, seizure-free rates are low in pharmacoresistant patients undergoing late adjunctive therapy. In preselected patient populations derived from double-blind studies, long-term seizure reduction and responder rates support sustained ZNS efficacy, good adherence and long-term retention. Adverse effects include somnolence and weight decrease, but data suggest that long-term treatment with ZNS is safe with only rare newly occurring adverse effects, and good long-term tolerability also regarding mood, behavior, cognition and bone maturation.

Effects of adjunctive zonisamide treatment on weight and body mass index in children with partial epilepsy

BACKGROUND

Zonisamide has been associated with weight loss in children and adults.

AIMS OF THE STUDY

To assess the effects of adjunctive zonisamide on weight and body mass index (BMI) in children with partial epilepsy.

METHODS

A subanalysis was conducted of a Phase III trial and extension study, in which children with partial epilepsy received adjunctive zonisamide (target dose 8 mg/kg/day; maximum 500 mg/day). Changes in weight were correlated with skeletal development and sexual maturation.

RESULTS

Overall, 179 children (93 male, 86 female; age 6-18 years) received zonisamide (mean duration 370.6 days). Weight loss ≥ 5% was reported for 64 of 179 (35.8%) zonisamide-treated children. Of these, 46.9% were overweight/obese at study entry, compared with 23.4% at study end (P = 0.0007); 48.4% had normal weight at study entry, compared with 65.6% at study end (P = 0.03). Three patients were underweight at study entry, and four more became underweight by study end. No consistent correlations between weight loss and skeletal development or sexual maturation were observed.

CONCLUSIONS

Approximately one-third of children treated with zonisamide experienced ≥ 5% weight loss. Weight loss was most apparent in children with high baseline BMI values and did not appear to be associated with any consistent effects on growth and development.

Retention rate of zonisamide in intractable epilepsy

OBJECTIVES

To assess the effect and tolerability of zonisamide (ZNS) as adjunctive treatment for difficult-to-treat epilepsy in adult Scandinavian patients.

MATERIAL AND METHODS

151 outpatients (mean age: 42.5 years) from 18 centres in Denmark, Sweden and Norway were recruited to the study. 81.5% had focal epilepsy, and the mean number of previously tried AEDs was 4.5. The patients were given ZNS as add-on treatment, and the ZNS dosing and the visit frequency were governed by the treating physician. The primary efficacy endpoint was the retention rate after 12-month treatment. Assessments included also responder rate, type and frequency of adverse events, healthcare resource utilization (HCRU) and quality of life (QOLIE-31).

RESULTS

90 patients (59.6%) completed the study. Mean daily ZNS dose was 300.8 mg. After 12 months, 81 patients were still on ZNS, that is a retention rate of 53.6%. The mean reduction of seizure frequency at 12 months was 27%. Best effect was seen in those with focal and those with secondary generalized seizures. In the QOLIE-31, there was a mean increase from baseline of 4.8 points. The tolerability was generally good. The majority of side effects were CNS-related, dizziness, fatigue, seizure aggravation, and headache being most prevalent. 21.2% had adverse events leading to withdrawal of ZNS.

CONCLUSIONS

A retention rate of 53.6% after 1 year of treatment with ZNS is roughly in accordance with the retention rates found for lamotrigine, oxcarbazepine, levetiracetam and topiramate in drug-resistant patients.

Antiepileptic Drug Treatment in Children with Epilepsy

Most children with new-onset epilepsy achieve seizure freedom with appropriate antiepileptic drugs (AEDs). However, nearly 20 % will continue to have seizures despite AEDs, as either monotherapy or in combination. Despite the growing market of new molecules over the last 20 years, the proportion of drug-resistant epilepsies has not changed. In this review, we report the evidence of efficacy and safety based on phase III randomized controlled clinical trials (RCTs) of AEDs currently used in the paediatric population. We conducted a literature search using the PubMed database and the Cochrane Database of Systematic Reviews. We also analysed the RCTs of newer AEDs whose efficacy in adolescents and adults might suggest possible use in children. Most of the phase III trials on AEDs in children have major methodological limitations that considerably limit meaningful conclusions about comparative efficacy between old and new molecules. Since the efficacy of new drugs has only been reported versus placebo, the commonly held opinion that new and newer AEDs have a better safety profile than old ones does not appear to be supported by evidence. Despite limited solid evidence, pharmacological management has improved over the years as a consequence of increased awareness of some degree of specificity of treatment in relation to different epilepsy syndromes and attention to adverse events. Future research should be directed taking these factors, as well as the diversity of epilepsy, into consideration.

Safety and tolerability of zonisamide in paediatric patients with epilepsy

BACKGROUND

Zonisamide has recently been approved in Europe for the adjunctive treatment of partial seizures (with or without secondary generalisation) in adolescents and children aged ≥6 years.

AIM

To further assess the safety of adjunctive zonisamide in paediatric epilepsy patients.

METHODS

A pooled analysis of data from 17 studies (including four randomised, double-blind trials) was conducted. The safety population comprised patients aged ≤16 years receiving at least one dose of study drug. Assessments included treatment-emergent adverse events (TEAEs), clinical laboratory parameters, vital signs and electrocardiography.

RESULTS

The analysis included 398 patients treated with zonisamide (<12 years, n = 191; 12-16 years, n = 207). All but seven patients received zonisamide as adjunctive therapy. Mean duration of exposure was 318.7 days (mean dose, 253.1 mg/day). Most TEAEs were of mild or moderate intensity. The most frequently reported treatment-related TEAEs were decreased appetite (15.6%), somnolence (12.1%), fatigue (9.3%), dizziness (6.0%), decreased weight (5.8%), irritability (5.8%) and headache (5.3%). Incidence of serious zonisamide-related TEAEs was low (3.5% overall). TEAEs most commonly leading to discontinuation were lethargy (1.0%) and fatigue (1.0%). TEAEs of decreased weight and decreased appetite occurred in 28 (7.0%) and 78 (19.6%) patients, respectively. Twenty-eight patients had decreased bicarbonate levels, but there were no reports of respiratory alkalosis or metabolic acidosis. No changes in vital signs of clinical concern were observed and there were no reports of clinically significant electrocardiogram abnormalities with zonisamide treatment.

CONCLUSION

Zonisamide demonstrated an acceptable safety profile when used as adjunctive treatment in paediatric patients.

[New aspects in the field of epilepsy]

Regarding epilepsy several new developments can be reported. The International League Against Epilepsy (ILAE) has suggested a new definition of epilepsy, for the first time including a definition of epilepsy resolution. Progress in the diagnosis relates to new genetic findings, improvements in magnetic resonance imaging (MRI) and the increasing use of stereo electroencephalograms (sEEG). Regarding treatment there are new clinically relevant data on the pathophysiology and prevention of sudden unexpected death in epilepsy (SUDEP). Zonisamide has been approved by the European Medicines Agency (EMA) for monotherapy in adults with focal seizures and combination therapy in children aged ≥ 6 years. Retigabin and perampanel have been approved but are currently taken off the market in Germany (only) because the Gemeinsamer Bundesausschuss (GBA, Joint Federal Committee) did not find any additional therapeutic value as compared to lamotrigine due to a lack of data. A decision regarding a new application for perampanel is pending. Regarding surgical treatment novel ablation techniques (e.g. stereotactic radiofrequency and laser ablation as well as focussed ultrasound ablation) and brain stimulation paradigms are under investigation. Experimental studies, generously supported by the European Union (EU) and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) are focusing on (opto-)genetic (e.g. using lentoviral transfection), epigenetic (e.g. micro-RNA-related) approaches and on the investigation of neuronal micronetworks.