Adjunctive Rufinamide in Children with Lennox-Gastaut Syndrome: A Literature Review

Rufinamide, a Triazole-Derived Antiepileptic Drug, Stimulates Ca2+-Activated K+ Currents While Inhibiting Voltage-Gated Na+ Currents

Rufinamide (RFM) is a clinically utilized antiepileptic drug that, as a triazole derivative, has a unique structure. The extent to which this drug affects membrane ionic currents remains incompletely understood. With the aid of patch clamp technology, we investigated the effects of RFM on the amplitude, gating, and hysteresis of ionic currents from pituitary GH₃ lactotrophs. RFM increased the amplitude of Ca²⁺-activated K⁺ currents (I_K(Ca)) in pituitary GH₃ lactotrophs, and the increase was attenuated by the further addition of iberiotoxin or paxilline. The addition of RFM to the cytosolic surface of the detached patch of membrane resulted in the enhanced activity of large-conductance Ca²⁺-activated K⁺ channels (BK_Ca channels), and paxilline reversed this activity. RFM increased the strength of the hysteresis exhibited by the BK_Ca channels and induced by an inverted isosceles-triangular ramp pulse. The peak and late voltage-gated Na⁺ current (I_Na) evoked by rapid step depolarizations were differentially suppressed by RFM. The molecular docking approach suggested that RFM bound to the intracellular domain of K_Ca1.1 channels with amino acid residues, thereby functionally affecting BK_Ca channels' activity. This study is the first to present evidence that, in addition to inhibiting the I_Na, RFM effectively modifies the I_K(Ca), which suggests that it has an impact on neuronal function and excitability.

Therapeutic Drug Monitoring for Rufinamide in Japanese Patients With Epilepsy: Focus on Drug Interactions, Tolerability, and Clinical Effectiveness

BACKGROUND

The purposes of this study were to assess drug interactions between rufinamide and concomitant antiepileptic drugs (AEDs) and to identify the therapeutic window for rufinamide.

METHODS

Serum samples (n = 1531) were obtained from 178 patients (aged 2-57 years), and clinical records were retrospectively reviewed to evaluate the safety and efficacy of rufinamide (mean observation time, 1073 ± 846 days).

RESULTS

Rufinamide exhibited linear pharmacokinetics at doses of up to 60 mg/kg (range, 50-3200 mg/d). Concomitant use of the enzyme-inducing AEDs such as phenytoin, carbamazepine, and phenobarbital reduced rufinamide concentrations by 43.4%, 13.2%, and 30.3%, respectively. By contrast, concomitant use of valproate significantly elevated rufinamide concentrations. Clinical response was seen in 41 patients (23.0%), with a median therapeutic concentration (interquartile range) of 20.6 mcg/mL (13.3-27.0). There was no difference in the therapeutic concentrations between seizure types, but patients with tonic/atonic seizures tended to have higher rufinamide concentrations. During the study period, adverse events were reported in 64 patients (35.8%), including somnolence, gastrointestinal disorders, dizziness, and irritability/behavior disorders. Conditional logistic regression analysis showed that patients administered a concentration greater than 20 mcg/mL had an 8.6-fold higher incidence of adverse events.

CONCLUSIONS

Therapeutic drug monitoring for rufinamide is clinically useful for predicting drug interactions between rufinamide and concomitant AEDs. When a patient has tonic/atonic seizures, careful titration is required for concentrations greater than 20 mcg/mL.

Safety and efficacy of rufinamide in children and adults with Lennox-Gastaut syndrome: A post hoc analysis from Study 022

BACKGROUND

Lennox-Gastaut syndrome (LGS) is a developmental and epileptic encephalopathy with the first symptoms usually appearing during early childhood. Due to the highly variable underlying etiologies, LGS cannot be considered as one disease but as an electro-clinical entity, often challenging to diagnose early and treat accordingly. The anti-seizure medication, rufinamide, is indicated for the adjunctive treatment of patients with LGS aged ≥1 year. This post hoc analysis assessed the safety and efficacy of adjunctive rufinamide for total and tonic-atonic seizures during Study 022 in children (aged <16 years) and adults (aged ≥16 years).

METHODS

Randomized, placebo-controlled, phase III Study 022 included patients with a diagnosis of LGS and a history of multiple seizure types (including tonic-atonic or astatic seizures and atypical absence seizures; ≥90 seizures in the month prior to baseline). Assessments included monitoring of treatment-emergent adverse events (TEAEs), percent change in tonic-atonic seizure frequency/28 days during the double-blind phase relative to study baseline (a primary endpoint), and percentage of patients with ≥25%, ≥50%, or ≥75% reduction in seizure frequency relative to baseline.

RESULTS

Of 138 enrolled patients, 74 received rufinamide (<16 years, n = 49 [66%]) and 64 received placebo (<16 years, n = 43 [67%]). Incidence of TEAEs was generally similar between age groups. The frequency (per 28 days) of tonic-atonic seizures was reduced with rufinamide (vs. placebo) in both younger and older patients: age <16 years (-41% vs. -6%), age ≥16 years (-55% vs. +16%) (p < 0.025; both age groups). In patients aged <16 years receiving rufinamide, 38% and 17% achieved ≥50% and ≥75% reductions in tonic-atonic seizure frequency vs. 18% and 3% with placebo, respectively. Corresponding responder rates for patients aged ≥16 years were 52% and 32% (rufinamide) vs. 15% and 5% (placebo), respectively.

CONCLUSIONS

In this post hoc analysis, adjunctive rufinamide was well tolerated and improved seizure control in patients with LGS, irrespective of age.

Efficacy and safety of rufinamide as adjunctive therapy in patients with Lennox Gastaut syndrome: A systematic review and Meta-analysis

INTRODUCTION

Rufinamide is an antiseizure medication that acts through sodium channels and is found to be efficacious in patients with Lennox Gastaut syndrome (LGS). However, no systematic review has been conducted in LGS patients to provide an estimate of the efficacy and safety of rufinamide.

METHODS

Different electronic databases were searched for articles describing the use of rufinamide in patients with LGS. For determining primary efficacy outcomes as compared to placebo, we included only studies comparing the efficacy of rufinamide with placebo in LGS patients. We performed an additional analysis to include other uncontrolled studies with a minimum sample size of 20 to provide a more comprehensive estimate of efficacy.

RESULTS

A total of ten studies included 557 patients. Out of them, five studies were placebo-controlled, enrolling a total of 265 patients in the rufinamide group and 203 patients in the placebo group. The average percentage reduction in total seizure frequency per 28 days during the double-blind phase was 29.3% in the rufinamide group compared with 8.3% in the placebo group (difference between the two groups was 20.9%, 95%CI-14.4%-27.3%, p <0.00001). Even for individual seizure types like tonic-clonic seizures, atypical absence seizures, atonic seizures, focal seizures, and myoclonic seizures, rufinamide was more efficacious than placebo(p<0.00001). The number of patients with at least one treatment-emergent adverse effects was significantly higher in rufinamide treated patients (60.2%vs50.7%, p=0.02, RR-1.24(1.03,1.51).

CONCLUSION

Rufinamide is efficacious as adjunctive therapy in patients with LGS in terms of reduction in total seizure frequency and has mild adverse reaction.

Expanding the Treatment Landscape for Lennox-Gastaut Syndrome: Current and Future Strategies

Lennox-Gastaut syndrome (LGS), a childhood-onset severe developmental and epileptic encephalopathy (DEE), is an entity that encompasses a heterogenous group of aetiologies, with no single genetic cause. It is characterised by multiple seizure types, an abnormal EEG with generalised slow spike and wave discharges and cognitive impairment, associated with high morbidity and profound effects on the quality of life of patients and their families. Drug-refractory seizures are a hallmark and treatment is further complicated by its multiple morbidities, which evolve over the patient's lifetime. This review provides a comprehensive overview of the current and future options for the treatment of seizures associated with LGS. Six treatments are specifically indicated as adjunct therapies for the treatment of seizures associated with LGS in the US: lamotrigine, clobazam, rufinamide, topiramate, felbamate and most recently cannabidiol. These therapies have demonstrated reductions in drop seizures in 15%-68% of patients across trials, with responder rates (≥ 50% reduction in drop seizures) of 37%-78%. Valproate is still the preferred first-line treatment, generally in combination with lamotrigine or clobazam. Other treatments frequently used off-label include the broad spectrum anti-epileptic drugs (AED) levetiracetam, zonisamide and perampanel, while recent evidence from observational studies has indicated that a newer AED, the levetiracetam analogue brivaracetam, may be effective and well tolerated in LGS patients. Other treatments in clinical development include fenfluramine in late phase III, perampanel, soticlestat-OV953/TAK-953, carisbamate and ganaxolone. Non-pharmacologic interventions include the ketogenic diet, vagus nerve stimulation and surgical interventions; these are also expanding, with the potential for less invasive techniques for corpus callosotomy that have promise for reducing complications. However, despite these advancements, patients continue to experience a significant burden. Because LGS is not a single entity, tailoring of treatment is needed as opposed to a 'one size fits all' approach. Further research is needed into the underlying aetiologies and pathophysiology of LGS, together with advancements in treatments that encompass the spectrum of seizures associated with this complex syndrome.

Cognitive, adaptive, and behavioral effects of adjunctive rufinamide in Lennox-Gastaut syndrome: A prospective observational clinical study

INTRODUCTION

Lennox-Gastaut syndrome (LGS) is a severe pediatric epilepsy syndrome characterized by multiple drug-resistant seizure types. Children with LGS usually experience cognitive regression, and LGS is almost always associated with moderate to severe cognitive impairment. Rufinamide (RFM) was approved by the European Medicines Agency in 2007 for the adjunctive treatment of seizures associated with LGS in patients ≥4 years of age. The primary objective of our study was to assess cognitive, adaptive, and behavior functioning of patients with LGS after 12 months of RFM therapy.

METHODS

This was an observational, multicenter, prospective study involving 16 patients diagnosed with LGS aged between 7 and 58 years (mean = 22 ± 16.3). Fourteen of 16 patients were already on therapy with 3 antiseizure drugs and 2/16 with 4 antiseizure drugs; RFM has been added with 100 mg/week increments up to a dose of 300-2400 mg/day. The participants and their parents underwent a neuropsychological evaluation for the assessment of intellectual, adaptive, and emotional/behavioral functioning (Leiter International Performance Scale-Revised (LEITER-R), Vineland, and Child Behavior CheckList (CBCL), respectively) before the RFM introduction (baseline) and 12 months after the RFM therapy (T2). Physical and neurological examination, electroencephalography (EEG) recording, seizure type and frequency, and adverse reactions were also considered.

RESULTS

After 12 months, the total intelligence quotient (IQ) assessed by LEITER-R did not show statistical significant changes, such as there were no statistically significant changes in adaptive functions, assessed by Vineland. Furthermore, there were no statistically significant changes in internalizing and externalizing problems assessed by CBCL.

CONCLUSION

Adjunctive treatment with RFM did not negatively affect cognitive, adaptive function, and emotional profile in patients with LGS after 1 year of follow-up.

Antiepileptic Drug Selection According to Seizure Type in Adult Patients with Epilepsy

Epilepsy is a common neurological disorder that is mainly treated using antiepileptic drugs. Several antiepileptic drugs such as phenobarbital, phenytoin, primidone, and ethosuximide were developed in the early 20th century. More than 10 types of antiepileptic drugs have been developed since the 1990s, and there are now more than 20 antiepileptic drugs in active clinical use. The choice of antiepileptic drugs is based on the clinical features of the seizure types, electroencephalogram findings, epileptic syndrome, and drug stability. Currently there are 19 antiepileptic drugs approved by the Korean Food and Drug Administration, 18 of which (with the exclusion of brivaracetam) are covered by the National Health Insurance Service in Korea. We reviewed the selection of antiepileptic drugs according to the classification of epileptic seizures.