Flexible dosing of adjunctive zonisamide in the treatment of adult partial-onset seizures: a non-comparative, open-label study (ZEUS)

A randomized, controlled, double-blind, crossover trial of zonisamide in myoclonus-dystonia

OBJECTIVE

To evaluate the efficacy and safety of zonisamide in patients with myoclonus-dystonia.

METHODS

We conducted a randomized, double-blind, placebo-controlled crossover trial of zonisamide (300 mg/d) in 24 patients with myoclonus-dystonia. Each treatment period consisted of a 6-week titration phase followed by a 3-week fixed-dose phase. The periods were separated by a 5-week washout period. The co-primary outcomes were action myoclonus severity (section 4 of the Unified Myoclonus Rating Scale [UMRS 4]) and myoclonus-related functional disability (UMRS 5). Secondary outcomes included dystonia severity, assessed with the movement and disability subscales of the Burke-Fahn-Marsden-Dystonia Rating Scale (BFM), the Clinical Global Impression-Improvement scale (CGI), and safety measures. Wilcoxon signed-rank tests for paired data were used to analyze treatment effects.

RESULTS

Twenty-three patients (11 men, 12 women) were analyzed in the intention-to-treat analysis. Zonisamide significantly improved both action myoclonus (median improvement [95% confidence limits] -5 [-9.25 to -1.44], p = 0.003) and myoclonus-related functional disability (median improvement [95% confidence limits] -2 [-2.58 to -2.46], p = 0.007) compared to placebo. Zonisamide also significantly improved dystonia (BFM movement) compared to placebo (median improvement [95% confidence limits] -3 [-8.46 to 0.03], p = 0.009). No difference was found between zonisamide and placebo with respect to the CGI (median improvement [95% confidence limits] -1 [-1.31 to 0.09], p = 0.1). Zonisamide was well-tolerated.

CONCLUSIONS

Zonisamide is well-tolerated and effective on the motor symptoms of myoclonus-dystonia.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that zonisamide improves myoclonus and related disability in patients with myoclonus-dystonia.

Evaluation of safety and efficacy of zonisamide in adult patients with partial, generalized, and combined seizures: an open labeled, noncomparative, observational Indian study

A prospective, multicentric, noncomparative open-label observational study was conducted to evaluate the safety and efficacy zonisamide in Indian adult patients for the treatment of partial, generalized, or combined seizures. A total of 655 adult patients with partial, generalized, or combined seizures from 30 centers across India were recruited after initial screening. Patients received 100 mg zonisamide as initiating dose as monotherapy/adjunctive therapy for 24 weeks, with titration of 100 mg every 2 weeks if required. Adverse events, responder rates, and seizure freedom were observed every 4 weeks. Efficacy and safety were also assessed using Clinicians Global Assessment of Response to Therapy and Patients Global Assessment of Tolerability to Therapy, respectively. Follow-up was conducted for a period of 24 weeks after treatment initiation. A total of 655 patients were enrolled and received the treatment and 563 completed the evaluation phase. A total of 20.92% of patients received zonisamide as monotherapy or alternative monotherapy and 59.85% patients received zonisamide as first adjunctive therapy. Compared with baseline, 41.22% of patients achieved seizure freedom and 78.6% as responder rate at the end of 24 week study. Most commonly reported adverse events were loss of appetite, weight loss, sedation, and dizziness, but discontinuation due to adverse events of drug was seen in 0.92% of patients. This open label real-world study suggests that zonisamide is an effective and well-tolerated antiepileptic drug in Indian adults for treatment of partial, generalized as well as combined seizures type. No new safety signals were observed.

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.

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.

Zonisamide in clinical practice

Zonisamide is currently licensed in Europe and the USA for the adjunctive treatment of partial seizures (with or without secondary generalization) in adults, based on the results of four pivotal, randomized, double-blind, placebo-controlled trials. It is also licensed in Europe as monotherapy for adults with newly diagnosed partial epilepsy, based on the results of a randomized, double-blind, non-inferiority trial. Because clinical trials are conducted under tightly controlled conditions, using rigid dosing schedules and employing strict exclusion/exclusion criteria, there is a need for 'real-world' evidence of an antiepileptic drug's effectiveness and tolerability in clinical practice, where patients are much more diverse in terms of clinical characteristics and treatment is tailored to the individual's specific needs. Several studies have demonstrated that adjunctive treatment with zonisamide is effective when administered under everyday clinical practice conditions, with a favourable safety/tolerability profile similar to that observed in clinical trials. In the Zonisamid im Alltag Der Epilepsiepatienten (ZADE) study, almost 80% of patients showed a reduction in seizure frequency of ≥50% over a median follow-up of 18 weeks, and over one-third of patients became seizure free. Data from these clinical practice studies also indicate that zonisamide is effective and generally well tolerated when administered as a first-line adjunctive treatment and is associated with high retention rates and improvements in quality of life. Evidence from these clinical practice studies therefore complements data from zonisamide's clinical trial programme, providing pragmatic information on the likely benefits and risks of treatment under real-life conditions.

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.

Review of therapeutic options for adjuvant treatment of focal seizures in epilepsy: focus on lacosamide

Epilepsy is one of the most common serious neurological conditions worldwide, with an age-adjusted incidence of approximately 50 per 100,000 persons per year in developed countries. Antiepileptic therapy can result in long-term remission in 60-70% of patients, but many patients will require combination treatment to achieve optimal seizure control, as monotherapy is ineffective at controlling seizures in 30-53% of patients. Despite the increase in available treatment options, patient outcomes have not improved significantly and there is still a need for more effective therapies. Drugs used in the treatment of focal-onset seizures are a diverse range of compounds, and in most cases their mechanism of action is unknown or poorly defined. This review discusses the efficacy and safety of the newer adjuvant antiepileptic therapies that may improve outcomes in patients unresponsive to monotherapy, including clobazam, vigabatrin, lamotrigine, gabapentin, topiramate, tiagabine, levetiracetam, oxcarbazepine, pregabalin, zonisamide and eslicarbazepine, with focus on lacosamide. Lacosamide has been shown to exert its anticonvulsant effects predominantly by enhancement of the slow inactivation of voltage-gated sodium channels. Lacosamide is indicated for use as adjuvant treatment of focal-onset seizures in patients with epilepsy, and there is some evidence that it may also be of use in patients with status epilepticus and cancer patients with epilepsy. The efficacy of lacosamide has been assessed in three randomized, double-blind, placebo-controlled clinical trials, all of which have shown lacosamide to be effective at reducing seizure frequency and increasing 50% responder rates in patients with focal-onset seizures. Long-term lacosamide treatment is generally well tolerated and is not associated with significant drug interactions; the availability of an intravenous form of the drug also makes it particularly useful for a broad range of patients.

Effect of antiepileptic drugs on the postictal state. A critical overview

Although postictal events contribute to seizure severity and thus affect quality of life, the effect of antiepileptic drugs (AEDs) on the postictal state is not well known. This review assesses the available evidence from randomized controlled trials on the effect of AEDs on postictal events. The instruments used in AED trials include postictal items of The Liverpool Seizure Severity Scale (LSSS) and Seizure Severity Scale (SSQ) and postictal recovery of electroencephalography (EEG) background activity. The effect of AEDs on postictal components of LSSS, if documented separately or at all, was either too small to be clinically significant (for lamotrigine) or not different from that of controls (topiramate, valproate). However, lacosamide showed improvement on the SSQ over placebo, and levetiracetam was associated with a speedier postictal recovery of EEG background activity compared with placebo. Although measuring the effect of AEDs on postictal state is of great clinical interest, the limited evidence found in this review suggests that further work is needed to evaluate current instruments used to assess AED-associated changes in postictal events.