Rufinamide add-on therapy for refractory epilepsy

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.

Rufinamide add-on therapy for drug-resistant epilepsy

BACKGROUND

Epilepsy is a central nervous system disorder (neurological disorder). Epileptic seizures are the result of excessive and abnormal cortical nerve cell electrical activity in the brain. Despite the development of more than 10 new antiepileptic drugs (AEDs) since the early 2000s, approximately a third of people with epilepsy remain resistant to pharmacotherapy, often requiring treatment with a combination of AEDs. In this review, we summarised the current evidence regarding rufinamide, a novel anticonvulsant medication, which, as a triazole derivative, is structurally unrelated to any other currently used anticonvulsant medication when used as an add-on treatment for drug-resistant epilepsy. In January 2009, rufinamide was approved by the US Food and Drug Administration for the treatment of children four years of age and older with Lennox-Gastaut syndrome. It is also approved as an add-on treatment for adults and adolescents with focal seizures. This is an updated version of the original Cochrane Review published in 2018.

OBJECTIVES

To evaluate the efficacy and tolerability of rufinamide when used as an add-on treatment for people with drug-resistant epilepsy.

SEARCH METHODS

We imposed no language restrictions. We contacted the manufacturers of rufinamide and authors in the field to identify any relevant unpublished studies.

SELECTION CRITERIA

Randomised, double-blind, placebo-controlled, add-on trials of rufinamide, recruiting people (of any age or gender) with drug-resistant epilepsy.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion and extracted the relevant data. We assessed the following outcomes: 50% or greater reduction in seizure frequency (primary outcome); seizure freedom; treatment withdrawal; and adverse effects (secondary outcomes). Primary analyses were intention-to-treat (ITT) and we presented summary risk ratios (RRs) with 95% confidence intervals (CIs). We evaluated dose response in regression models. We carried out a risk of bias assessment for each included study using the Cochrane 'Risk of bias' tool and assessed the overall certainty of evidence using the GRADE approach.

MAIN RESULTS

The review included six trials, representing 1759 participants. Four trials (1563 participants) included people with uncontrolled focal seizures. Two trials (196 participants) included individuals with established Lennox-Gastaut syndrome. Overall, the age of adults ranged from 18 to 80 years and the age of children ranged from 4 to 16 years. Baseline phases ranged from 28 to 56 days and double-blind phases from 84 to 96 days. Five of the six included trials described adequate methods of concealment of randomisation, and only three described adequate blinding. All analyses were by ITT. Overall, five studies were at low risk of bias and one had unclear risk of bias due to lack of reported information around study design. All trials were sponsored by the manufacturer of rufinamide and therefore were at high risk of funding bias. The overall RR for 50% or greater reduction in seizure frequency was 1.79 (95% CI 1.44 to 2.22; 6 randomised controlled trials (RCTs), 1759 participants; moderate-certainty evidence), indicating that rufinamide (plus conventional AED) was significantly more effective than placebo (plus conventional AED) in reducing seizure frequency by at least 50% when added to conventionally used AEDs in people with drug-resistant focal epilepsy. Data from only one study (73 participants) reported seizure freedom: RR 1.32 (95% CI 0.36 to 4.86; 1 RCT, 73 participants; moderate-certainty evidence). The overall RR for treatment withdrawal (for any reason and due to AED) was 1.83 (95% CI 1.45 to 2.31; 6 RCTs, 1759 participants; moderate-certainty evidence), showing that rufinamide was significantly more likely to be withdrawn than placebo. Most adverse effects were significantly more likely to occur in the rufinamide-treated group. Adverse events significantly associated with rufinamide were headache, dizziness, somnolence, vomiting, nausea, fatigue, and diplopia. The RRs for these adverse effects were as follows: headache 1.36 (95% Cl 1.08 to 1.69; 3 RCTs, 1228 participants; high-certainty evidence); dizziness 2.52 (95% Cl 1.90 to 3.34; 3 RCTs, 1295 participants; moderate-certainty evidence); somnolence 1.94 (95% Cl 1.44 to 2.61; 6 RCTs, 1759 participants; moderate-certainty evidence); vomiting 2.95 (95% Cl 1.80 to 4.82; 4 RCTs, 777 participants; low-certainty evidence); nausea 1.87 (95% Cl 1.33 to 2.64; 3 RCTs, 1295 participants; moderate-certainty evidence); fatigue 1.46 (95% Cl 1.08 to 1.97; 3 RCTs, 1295 participants; moderate-certainty evidence); and diplopia 4.60 (95% Cl 2.53 to 8.38; 3 RCTs, 1295 participants; low-certainty evidence). There was no important heterogeneity between studies for any outcomes. Overall, we assessed the evidence as moderate to low certainty due to wide CIs and potential risk of bias from some studies contributing to the analysis.

AUTHORS' CONCLUSIONS

For people with drug-resistant focal epilepsy, rufinamide when used as an add-on treatment was effective in reducing seizure frequency. However, the trials reviewed were of relatively short duration and provided no evidence for long-term use of rufinamide. In the short term, rufinamide as an add-on was associated with several adverse events. This review focused on the use of rufinamide in drug-resistant focal epilepsy, and the results cannot be generalised to add-on treatment for generalised epilepsies. Likewise, no inference can be made about the effects of rufinamide when used as monotherapy.

New Methods Used in Pharmacokinetics and Therapeutic Monitoring of the First and Newer Generations of Antiepileptic Drugs (AEDs)

The review presents data from the last few years on bioanalytical methods used in therapeutic drug monitoring (TDM) of the 1st-3rd generation and the newest antiepileptic drug (AEDs) cenobamate in patients with various forms of seizures. Chemical classification, structure, mechanism of action, pharmacokinetic data and therapeutic ranges for total and free fractions and interactions were collected. The primary data on bioanalytical methods for AEDs determination included biological matrices, sample preparation, dried blood spot (DBS) analysis, column resolution, detection method, validation parameters, and clinical utility. In conclusion, the most frequently described method used in AED analysis is the LC-based technique (HPLC, UHPLC, USLC) combined with highly sensitive mass detection or fluorescence detection. However, less sensitive UV is also used. Capillary electrophoresis and gas chromatography have been rarely applied. Besides the precipitation of proteins or LLE, an automatic SPE is often a sample preparation method. Derivatization was also indicated to improve sensitivity and automate the analysis. The usefulness of the methods for TDM was also highlighted.

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

Lennox-Gastaut syndrome (LGS) is a severe, childhood-onset, developmental epileptic encephalopathy, with different etiologies and co-morbidities. Seizure treatment in LGS represents a major challenge; new antiepileptic drugs (AEDs) are developed to especially address seizures resulting in high morbidity and mortality, such as drop seizures. Rufinamide (RFN) is one of the latest AEDs licensed for patients with LGS. Its mechanism of action involves sodium channels in a way that is unrelated to other AEDs. Here we discuss the use of adjunctive RFN in children and adolescents with LGS and its efficacy and safety profile, based on a systematic literature review. RFN shows a very favorable profile in terms of adverse events and drug-interactions in children. It is particularly effective on tonic-atonic seizures and spasms, impacting on the quality of life of the patients. Further studies are needed to clarify the interaction profile with the newest AEDs for LGS and to assess correlations between the etiology of LGS and drug response to individualize treatment and maximize efficacy.

Effect of Ibuprofen on Autophagy of Astrocytes During Pentylenetetrazol-Induced Epilepsy and its Significance: An Experimental Study

Epilepsy is a chronic neurological disease. Astrogliosis is an important pathological change in epileptic lesions. Studies have reported that ibuprofen can affect autophagy and/or inhibit cell proliferation in many diseases. This study investigated the effect and significance of ibuprofen on autophagy of astrocytes during pentylenetetrazol (PTZ) induced epilepsy. 60 male Sprague-Dawley (SD) rats were randomly divided into five groups: control group (received normal saline), PTZ group, 3-methyladenine (3-MA) + PTZ group, ibuprofen + PTZ group and 3-MA + ibuprofen + PTZ group. Dose of each agent was 35 mg/kg (PTZ), 10 mg/kg (3-MA) and 30 mg/kg (ibuprofen) and all drugs were administered intraperitoneally 15 times on alternate days (29 days). Human astrocytes were cultured in vitro. Behavioral performance (i.e., latency, grade and duration of seizures) and EEG of rats were observed and recorded. Proliferation of astrocytes was detected by CCK-8 method. Immunofluorescence and Western blot test were used to detect the expression of LC3 and GFAP. Mean number, grade and duration of seizures were markedly reduced in ibuprofen + PTZ group and 3-MA + ibuprofen + PTZ group (P < 0.05). Similarly, peak of EEG waves were markedly reduced in ibuprofen + PTZ group and 3-MA + ibuprofen + PTZ group (P < 0.05). Compared to the control group, the level of LC3 in ibuprofen group was significantly increased in vitro (P < 0.05). While, levels of LC3 were significantly higher and that of GFAP were significantly lower in ibuprofen + PTZ group (P < 0.05) compared to PTZ group in vivo. Ibuprofen reduces the proliferation of astrocytes by increasing autophagy, thus affecting the development of epilepsy. Therefore, ibuprofen may be used as an adjuvant to improve efficacy of treatment in epilepsy.

Rufinamide add-on therapy for refractory epilepsy

BACKGROUND

Epilepsy is a central nervous system disorder (neurological disorder). Epileptic seizures are the result of excessive and abnormal cortical nerve cell electrical activity in the brain. Despite the development of more than 10 new antiepileptic drugs (AEDs) since the early 2000s, approximately a third of people with epilepsy remain resistant to pharmacotherapy, often requiring treatment with a combination of AEDs. In this review, we summarised the current evidence regarding rufinamide, a novel anticonvulsant medication, which, as a triazole derivative, is structurally unrelated to any other currently used anticonvulsant medication, when used as an add-on treatment for refractory epilepsy. In January 2009, rufinamide was approved by the US Food and Drug Administration for treatment of children four years of age and older with Lennox-Gastaut syndrome. It is also approved as an add-on treatment for adults and adolescents with focal seizures.

OBJECTIVES

To evaluate the efficacy and tolerability of rufinamide when used as an add-on treatment in people with refractory epilepsy.

SEARCH METHODS

On 2 October 2017, we searched the Cochrane Epilepsy Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL) via the Cochrane Register of Studies Online (CRSO), MEDLINE (Ovid, 1946), ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP). We imposed no language restrictions. We also contacted the manufacturers of rufinamide and authors in the field to identify any relevant unpublished studies.

SELECTION CRITERIA

Randomised, double-blind, placebo-controlled, add-on trials of rufinamide, recruiting people (of any age or gender) with refractory epilepsy.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion and extracted the relevant data. We assessed the following outcomes: 50% or greater reduction in seizure frequency (primary outcomes); seizure freedom; treatment withdrawal; and adverse effects (secondary outcomes). Primary analyses were intention-to-treat (ITT) and we presented summary risk ratios (RR) with 95% confidence intervals (CI). We evaluated dose response in regression models. We carried out a risk of bias assessment for each included study using the Cochrane 'Risk of bias' tool and assessed the overall quality of evidence using the GRADE approach, which we presented in a 'Summary of findings' table.

MAIN RESULTS

The review included six trials, representing 1759 participants. Four trials (1563 participants) included people with uncontrolled focal seizures. Two trials (196 participants) included established Lennox-Gastaut syndrome. Overall, the age of the adults ranged from 18 to 80 years and the age of the infants ranged from four to 16 years. Baseline phase ranged from 28 to 56 days and double-blind phases from 84 to 96 days. Five of the six included trials described adequate methods of concealment of randomisation and only three described adequate blinding. All analyses were by ITT. Overall, five studies were at low risk of bias, and one had unclear risk of bias due to lack of reported information around study design. All trials were sponsored by the manufacturer of rufinamide, and therefore, were at high risk of funding bias.The overall RR for 50% or greater reduction in seizure frequency was 1.79 (95% CI 1.44 to 2.22; 6 RCTs; moderate-quality evidence) indicating that rufinamide (plus conventional AED) was significantly more effective than placebo (plus conventional AED) in reducing seizure frequency by at least 50%, when added to conventionally used AEDs in people with refractory focal epilepsy. The overall RR for treatment withdrawal (for any reason and due to AED) was 1.83 (95% CI 1.45 to 2.31; 6 RCTs; moderate-quality evidence) showing that rufinamide was significantly more likely to be withdrawn than placebo. In respect of adverse effects, most were significantly more likely to occur in the rufinamide-treated group. The adverse events significantly associated with rufinamide were: headache, dizziness, somnolence, vomiting, nausea, fatigue and diplopia. The RRs of these adverse effects were: headache 1.36 (95% Cl 1.08 to 1.69; 3 RCTs; high-quality evidence); dizziness 2.52 (95% Cl 1.90 to 3.34; 3 RCTs; moderate-quality evidence); somnolence 1.94 (95% Cl 1.44 to 2.61; 6 RCTs; moderate-quality evidence); vomiting 2.95 (95% Cl 1.80 to 4.82; 4 RCTs; low-quality evidence); nausea 1.87 (95% Cl 1.33 to 2.64; 3 RCTs; moderate-quality evidence); fatigue 1.46 (95% Cl 1.08 to 1.97; 3 RCTs; moderate-quality evidence); and diplopia 4.60 (95% Cl 2.53 to 8.38; 3 RCTs; low-quality evidence). There was no important heterogeneity between studies for any of the outcomes. Overall, we assessed the evidence as moderate to low quality, due to potential risk of bias from some studies contributing to the analysis and wide CIs.

AUTHORS' CONCLUSIONS

In people with drug-resistant focal epilepsy, rufinamide when used as an add-on treatment was effective in reducing seizure frequency. However, the trials reviewed were of relatively short duration and provided no evidence for the long-term use of rufinamide. In the short term, rufinamide as an add-on was associated with several adverse events. This review focused on the use of rufinamide in drug-resistant focal epilepsy and the results cannot be generalised to add-on treatment for generalised epilepsies. Likewise, no inference can be made about the effects of rufinamide when used as monotherapy.