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 We also contacted the manufacturers of rufinamide and authors in the field to identify any relevant unpublished studies.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.