Zonisamide in children and young adults with refractory epilepsy: an open label, multicenter Italian study

Bioequivalence of Different Formulations of Zonisamide Oral Suspensions: A Short Review

To satisfy the needs of pediatric and other patients with focal onset seizures who cannot swallow solid dosage forms of zonisamide, an oral liquid form of this drug is necessary in clinical practice. Although there are two oral suspensions of zonisamide with marketing authorization (MA), there are issues of availability and high cost which limit their use and inspire extemporaneous compounding. Extemporaneously compounded oral suspensions of zonisamide are prepared according to different formulas and vary in stability; therefore it is essential to test this characteristic. Bioequivalence of extemporaneously compounded oral suspensions has never been tested, and the efficacy and safety of zonisamide oral suspensions have generally not been demonstrated in clinical trials. As a narrow therapeutic window drug, zonisamide requires precision in dosing, which could be achieved only with dosage forms with established bioavailability, efficacy, and safety. In order to avoid underdosing and toxicity with zonisamide oral suspensions and utilize their full therapeutic potential, it is necessary to perform bioequivalence studies with each variation of extemporaneously compounded oral suspension and also clinical trials with both commercial and extemporaneous oral suspensions of zonisamide.

Effectiveness of zonisamide in childhood refractory epilepsy

INTRODUCTION

Zonisamide (ZNS) is a new generation antiepileptic drug (AED) used in refractory epilepsy. This study assessed the effectiveness and reliability of ZNS in childhood refractory epilepsy.

METHOD

Sixty-eight epilepsy patients who were followed up in the paediatric neurology clinic, between 2013 and 2019, and in whom add-on therapy ZNS had been added as their seizures had continued despite multiple drugs being used, were included in this retrospective study. Their demographic findings, seizure aetiology, pre-treatment and post-treatment electroencephalography findings, treatment responses and any side effects of the drugs given were assessed in these patients.

RESULTS

There were 46 (67.6%) patients in the refractory generalized epilepsy (RGE) group using multiple AEDs and 22 (32.35%) patients in the refractory focal epilepsy (RFE) group. Of these patients, 12 (17.65%) were being followed up for idiopathic epilepsy and 8 (11.76%) were being followed up for epilepsy of unknown aetiology. Twenty-two (32.36%) patients were followed up for structural abnormality, 8 patients (11.77%) were followed up for genetic disease, 4 patients (5.88%) were followed up for infectious sequel, 14 patients (20.59%) were followed up for metabolic reasons. In the RGE group, a more than 50% reduction was found in the seizures of 26 (56.5%) patients, while the seizures of 7 (15.2%) patients were found to have terminated completely. In the RFE group, a more than 50% reduction was found in the seizures of 19 (86.4%) patients, while the seizures of 2 (9.1%) patients were found to have terminated completely. The termination or a more than 50% reduction in seizures in 4 of the 6 patients followed up for a diagnosis of tuberous sclerosis complex (TSC) was significant.

CONCLUSION

ZNS is an effective and reliable option as an add-on therapy in paediatric refractory epilepsy, especially in focal epilepsy. It can also be considered for treatment in TSC patients.

Long-term effects of zonisamide in adult patients with intellectual disability

OBJECTIVE

This study aimed to evaluate the tolerability and efficacy of zonisamide (ZNS) in adult patients with drug-resistant epilepsy and intellectual disability (ID) at our epilepsy centre.

PATIENTS AND METHODS

By conducting a monocentric, open-label observational study based on standardized seizure records we retrospectively assessed 87 patients (39 female, mean age 40.6 ± 13.6, range 18-75 years) with ID and drug-resistant epilepsy. Evaluation, including calculation of retention rate, was performed for the intervals 3-6, 9-12 and 21-24 months after ZNS initiation. The Clinical Global Impressions Scale-Improvement (CGI-I) was used to detect qualitative changes in seizure severity and clinical status. Via regression analysis and the generalized estimating equations approach, we examined changes in body weight and impact of patient age also considering associations with other patient characteristics.

RESULTS

The retention rate after 24 months was 60%. 28% discontinued ZNS therapy due to increasing seizure frequency, lack of efficacy or adverse events (AEs). Sedation (38%), language impairment (19%), challenging behaviour (10%), mild rash (10%) and dizziness (10%) were the commonest AEs. The responder rate was 40%, eight patients (9%) became seizure free. We found CGI-I to be dose-dependent. Regarding changes in body weight, we observed no difference between patients continuing or withdrawing ZNS therapy and responders or non-responders. Though, we identified older age as a significant risk factor for weight loss.

CONCLUSIONS

Zonisamide may provide a safe and efficient therapeutic option for patients with ID and drug-resistant epilepsy. However, weight status should be carefully monitored, especially in elderly patients.

[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.

Pharmacokinetic considerations for anti-epileptic drugs in children

INTRODUCTION

Epilepsy is a chronic and debilitating neurological disease, with a peak of incidence in the first years of life. Today, the vast armamentarium of antiepileptic drugs (AEDs) available make even more challenging to select the most appropriate AED and establish the most effective dosing regimen. In fact, AEDs pharmacokinetics is under the influence of important age-related factors which cannot be ignored. Areas covered: Physiological changes occurring during development age (different body composition, immature metabolic patterns, reduced renal activity) can significantly modify the pharmacokinetic profile of AEDs (adsorption, volume of distribution, half-life, clearance), leading to an altered treatment response. We reviewed the main pharmacokinetic characteristics of AEDs used in children, focusing on age-related factors which are of relevance when treating this patient population. Expert opinion: To deal with this pharmacokinetic variability, physicians have at their disposal two tools: 1) therapeutic drug concentration monitoring, which may help to set the optimal therapeutic regimen for each patient and to monitor eventual fluctuation, and 2) the use of extended-release drug formulations, when available. In the next future, the development of 'ad-hoc' electronic dashboard systems will represent relevant decision-support tools making the AED therapy even more individualized and precise, especially in children.

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.

Efficacy and safety of zonisamide in Thai children and adolescents with intractable seizures

This retrospective study examined the efficacy and safety of zonisamide for Thai children and adolescents with intractable seizures. The medical records of 24 patients (13 male, 11 female), aged 2 to 18 years (median 11.5, mean 10.4) who received zonisamide were reviewed. The underlying illness, etiology of epilepsy, seizure types, previous and concomitant antiepileptic drugs, dosage, and adverse effects of the drug were collected. Zonisamide's efficacy was evaluated on the basis of seizure reduction rates. At final evaluation, 7 patients were still taking zonisamide from 4.7 to 10.3 mg/kg/d (median 8). One patient became seizure-free and the other 6 experienced favorable seizure control. The median duration of zonisamide therapy was 23.75 months (range 20.5-25 months). Minor adverse effects were reported in 41.6% of patients during the first 3 months of therapy. Zonisamide is an option for the treatment of intractable seizures with favorable seizure control in children and adolescents.

Zonisamide as a treatment for partial epileptic seizures: a systematic review

Although the majority of people with epilepsy have a good prognosis and their seizures can be well controlled with pharmacotherapy, up to one-third of patients can develop drug-resistant epilepsy, especially those patients with partial seizures. This unmet need has driven considerable efforts over the last few decades aimed at developing and testing newer antiepileptic agents to improve seizure control. One of the most promising antiepileptic drugs of the new generation is zonisamide, a benzisoxazole derivative chemically unrelated to other anticonvulsant agents. In this article, the authors present the results of a systematic literature review summarizing the current evidence on the efficacy and tolerability of zonisamide for the treatment of partial seizures. Of particular interest within this updated review are the recent data on the use of zonisamide as monotherapy, as they might open new therapeutic avenues.

The adverse event profile of zonisamide: a meta-analysis

The first aim of our study was to analyze the adverse events statistically significantly associated with zonisamide, through a systematic review and meta-analysis of available randomized placebo-controlled trials (RCTs). The second aim was to compare these results with those obtained from an analysis of non-RCTs and observational studies. Randomized controlled trials were identified using Medline (PubMed), EMBASE (Ovid), and Cochrane CENTRAL, from 1990 to September 2012. RevMan version 5.1 and OpenMeta[Analyst] were used for analyses of RCT and non-RCTs, respectively. Six eligible studies with 1184 patients between 12 and 80 years of age were included in RCTs analysis. Fifteen adverse events were investigated. In this first part of the analysis, no adverse events were statistically significantly associated with zonisamide. In the non-RCT analysis, a high incidence of weight loss and headache was found. In RCTs, zonisamide was statistically significantly associated with an increased risk of adverse event-related study withdrawals [RR (99% CI) = 1.81 (1.07-3.08)]. Although our study revealed no statistically significantly associated adverse effects (AEs) with zonisamide, this is very likely a consequence of the small numbers in the RCTs available. The limited data available from the studies appear to reveal no major safety concerns related to zonisamide. However, the high incidence of weight loss and headache in the non-RCTs suggests that these AEs could be of clinical significance.

Short-term efficacy and safety of zonisamide as adjunctive treatment for refractory partial seizures: a multicenter open-label single-arm trial in Korean patients

OBJECTIVE

To evaluate the efficacy and safety of adjunctive zonisamide (ZNS) therapy in Korean adults with uncontrolled partial epilepsy.

METHODS

Study patients had an average of at least one seizure per 4-week (averaged over a 12-week historical baseline) despite the use of one to three antiepileptic drugs. The starting dose of ZNS was 100mg/day, and was increased to 200mg/day after 2weeks. During the 12-week maintenance period, the dose of ZNS was adjusted to 200-400mg/day based on the physicians' discretion. The global evaluation scale (GES) and quality of life (QOLIE-31) were also evaluated.

RESULTS

A total of 121 patients were enrolled, of which 88 patients completed the study. The median percent reduction in weekly seizure frequency over the treatment period was 59.0%. The ≥50% and ≥75% responder rates were 57.3% and 38.5%, respectively. Seizure freedom over the treatment period was observed in 25 patients, but seizure freedom throughout the 16-week treatment period was attained in only 16 patients. On investigator's GES, 84 patients were considered improved, with 33 patients showing marked improvement. In QOLIE-31 scale, seizure worry improved significantly but emotional well-being deteriorated. Treatment-emergent adverse events (AEs) were reported in 80 patients. The most common AEs were dizziness (28.1%), somnolence (24.0%), anorexia (18.2%), headache (14.0%), nausea (13.2%), and weight loss (10.7%). Twenty-two patients discontinued the trial due to drug-related AEs.

CONCLUSIONS

Our results suggest that adjunctive ZNS therapy for the treatment of refractory partial epilepsy, though efficacious, is associated with significant tolerability problems.

Pharmacotherapy for children and adolescents with epilepsy

INTRODUCTION

Childhood epilepsies are the most frequent neurological problems that occur in children. Despite the introduction of new antiepileptic drugs (AEDs) 25-30% of children with epilepsy remain refractory to medical therapy.

AREAS COVERED

This review aims to highlight the main published data on the treatment of childhood epilepsy. The electronic database, PubMed, and abstract proceedings were used to identify studies. The aim of antiepileptic therapy should be to provide complete seizure control, if possible without the burden of any side effect. Since 1993, new agents have been approved for use as an antiepileptic. Although there are few published data (especially in pediatric populations) to establish that the second-generation AEDs are more efficacious than the older AEDs, they appear to have better tolerability.

EXPERT OPINION

Old AEDs are efficacious agents that continue to play a major role in the current treatment of epilepsy. These agents actually remain the first-line treatment for many specific seizure types or epileptic syndromes. The new AEDs were initially approved as adjunct agents and--subsequently--as monotherapy for various seizure types in the adult and children. Despite these improvements, few AEDs are now considered to be a first-choice for the treatment of epilepsy in children.

Efficacy and tolerability of zonisamide as add-on in brain tumor-related epilepsy: preliminary report

BACKGROUND

Zonisamide (ZNS) is an antiepileptic drug (AED) with broad spectrum action that demonstrated a good efficacy in controlling seizures as add-on in adult and pediatric epilepsy. To date there have been no studies on ZNS in patients with brain tumor-related epilepsy (BTRE).

AIM OF THE STUDY

To evaluate efficacy and tolerability of ZNS as add-on in BTRE.

METHODS

We followed six patients suffering from BTRE who had already been treated with other AEDs and who had had not experienced adequate seizure control. Three patients underwent chemotherapy while being treated with ZNS. Mean duration of follow-up was 8 months.

RESULTS

Mean seizure number in the last month prior to the introduction of ZNS had been 27.7/month. ZNS mean dosage was of 283.3 mg/day. At last follow-up, the mean seizure number was reduced to 8.8/month. Responder rate was 83.3%.Two patients discontinued the drug because of side effects. There were no other reported side effects.

CONCLUSIONS

Preliminary data on the use of ZNS in add-on in patients with BTRE indicate that this drug may represent a valid alternative as add-on in this particular patient population. However, larger samples are necessary to draw definitive conclusions.

Long-term safety and effectiveness of zonisamide in the treatment of epilepsy: a review of the literature

Zonisamide (ZNS) efficacy and safety in epilepsy have been demonstrated in four double-blind, placebo-controlled studies. In the present article, we examined all long-term studies performed with this drug. Nine open-label studies, in which ZNS had been administered as an add-on or as monotherapy to epileptic patients for at least 6 months, were selected for our analysis. Four outcome measures were searched. Retention of this drug after 1 year varied between 45% and 65%. The percentages of patients achieving a >/=50% seizure reduction, with respect to baseline, ranged between 37% and 65%. In patients with drug-resistant forms of epilepsy, the percentage of patients reaching a 6-month seizure freedom period was 9%. The percentages of patients who discontinued the experimental drug due to adverse effects ranged between 4% and 24%. Somnolence and dizziness were the most frequently reported adverse effects. Long-term studies demonstrate that ZNS has a good efficacy and tolerability profile, and support its use as adjunctive therapy for epileptic patients.