Broad-spectrum efficacy of zonisamide at 12 months in children with intractable epilepsy

Efficacy, tolerability, and safety of zonisamide in children with epileptic spasms: A systematic review and meta-analysis

BACKGROUND

Valproate, levetiracetam, benzodiazepines, and topiramate are antiseizure medications (ASMs) considered to have definite efficacy in reducing the frequency of epileptic spasm frequency, apart from ketogenic dietary therapies. Although zonisamide has also been shown to have efficacy as second-line ASM for epileptic spasms, various studies have conflicting results in literature. This systematic review aims to summarize clinical studies regarding the efficacy of zonisamide for epileptic spasms.

METHODS

We conducted a systematic literature search collating all available literature. The primary objective was to determine efficacy in terms of proportion with complete spasm resolution, we also intended to determine proportion with at least 50% spasm reduction, hypsarrhythmia resolution, and nature/frequency of adverse effects. All prospective/retrospective, controlled/uncontrolled studies describing the use of zonisamide with epileptic spasms were included in the qualitative review excluding case reports, but for metanalysis pertaining to key outcomes, we included studies with at least 10 participants.

RESULTS

A total of nineteen publications were found eligible for inclusion in the qualitative review, out of 101 search items. A total of 401 children with epileptic spasms were tried up to a maximum of 9.9-35 mg/kg/day dose with only mild adverse effects in a few patients. Total 20.8% (95% CI-11.4%-29.2%) and 23.4% (95% CI-17.8%-29.1%) patients had complete cessation of spasms and at least a 50% reduction in total spasm frequency as compared to baseline after starting zonisamide. Similarly, 20.3% (95% CI-10.1%-30.5%) had resolution of hypsarrhythmia in EEG after starting zonisamide.

CONCLUSION

Zonisamide can reduce spasms in 21% of children with epileptic spasms, without major adverse effects. But there are only limited studies on epileptic spasms of sufficient quality to give high confidence in meta-analysis. Large controlled trials are needed in this regard to provide high-quality evidence favoring/disfavoring its use in patients with epileptic spasms.

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.

Update on the newer antiepileptic drugs in child neurology: advances in treatment of pediatric epilepsy

The goal of epilepsy treatment is the prevention of recurrent seizures, and antiepileptic drugs (AEDs) are the mainstay. Uncontrolled seizures may cause medical, developmental, and psychologic disturbances. Treatment advances include 1) identification of the basic mechanisms of epilepsy and action of AEDs, 2) the introduction of many new AEDs, and 3) the use of neurostimulation, starting with vagus nerve stimulation. We must balance the efficacy of an AED versus its side effects, which if persistent, lead to patient discontinuation of the AED. Although all AEDs have a proven efficacy, they are differentiated by their efficacy for a given seizure type or epilepsy syndrome versus the side effects or tolerability. The many new AEDs give us a larger armamentarium for epilepsy treatment. We refer to studies and expert opinion consensus.

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.

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

PURPOSE

To report on the first multicenter Italian experience with zonisamide as an add-on drug for refractory generalised or partial epilepsy in children, adolescents and young adults.

METHODS

The patients were enrolled in a prospective, add-on, open-label treatment study from eight Italian centres for children and adolescent epilepsy care. Eighty-two young patients (45 males, 37 females), aged between 3 and 34 years (mean 13.1 years), all affected by partial (47) or generalised (35) refractory epilepsy, were enrolled in the study. ZNS was added to the baseline therapy at a starting dose of 1 mg/kg/day twice daily. This dose was increased by 2 mg/kg every 1-2 weeks over a period of up 3 months, according to the patient's response and tolerability, up to a maximum dose of 12 mg/kg. ZNS was given at the mean daily dose of 5.7/mg/kg/24 h (range 1-12 mg/kg).

RESULTS

After a mean follow-up period of 11.9 months (range 2-64 months), 9 patients (10.9%) were seizure-free. The number of seizures decreased by 50-99% in 31 cases (37.8%), by 25-49% in 5 cases (6.1%), remained the same in 29 cases (35.4%) and increased in 8 cases (9.7%). After 15 months of follow-up, 61 patients (74.4%) were still taking ZNS, while the remaining 21 (25.6%) had stopped. Twenty-two patients (26.8%) reported adverse effects while taking ZNS. They generally appeared during the first weeks of treatment, and were mild to moderate. The most frequent adverse effects were irritability and a reduced appetite.

CONCLUSION

ZNS effectively reduced seizure frequency in this pediatric population with both partial and generalised crypto/symptomatic refractory epilepsy. Its overall tolerability was good.

Antiepileptic drugs and liver disease

Antiepileptic drugs (AEDs) are no longer restricted to the treatment of epilepsy. These are widely used in a broad spectrum of psychiatric and neurological disorders. Liver plays a major role in the metabolism of a majority of these drugs. Hepatotoxicity is rare, but a real concern when initiating therapy. Likewise, liver disease can adversely affect the biotransformation of some of these drugs. This manuscript addresses the significance of elevated liver enzymes associated with AED use, the role of therapeutic drug monitoring, pharmacokinetics during liver disease and potential risk of hepatotoxicity.