Onset of action and seizure control in Lennox-Gaustaut syndrome: focus on rufinamide

Rufinamide: A New Antiepileptic Medication for the Treatment of Seizures Associated with Lennox-Gastaut Syndrome

Objective

To review the pharmacology, pharmacokinetics, efficacy, and safety of rufinamide in the treatment of epileptic seizures and describe its potential place in therapy.

Data sources

MEDLINE (1966–January 2010) and PubMed (1966–January 2010) literature searches were conducted to identify primary literature investigating rufinamide. References from selected publications discussing rufinamide, as well as the package insert, were reviewed.

Study selection and data extraction

Published controlled trials describing the efficacy and safety of rufinamide were given preference. Available abstracts were also reviewed. Four published trials were identified and included and a retrospective review of the clinical use of rufinamide was also analyzed. The remainder of the information described is from 4 abstracts.

Data synthesis

Rufinamide is a new antiepileptic agent that differs structurally from other antiepileptic drugs and is approved as adjunctive therapy for Lennox-Gastaut syndrome (LGS). It presumably provides its antiseizure activity by prolonging sodium channel inactivity, stabilizing cell membranes. It is absorbed and metabolized extensively, then excreted renally as an inactive metabolite. Clinical trials show that adjunctive rufinamide is effective at reducing seizure frequency in patients with LGS and refractory partial seizures. Rufinamide showed no effect on cognitive function in patients with refractory partial seizures. Short-term adverse event rates were similar to those of placebo. Safety data from long-term studies show that rufinamide is well tolerated, causing headache, dizziness, and fatigue at rates of >10%. Rufinamide has few clinically relevant drug interactions, although it does increase phenytoin serum concentrations, while valproate increases rufinamide serum concentrations.

Conclusions

Data show that rufinamide is safe and effective as an adjunctive agent for LGS and may be used to treat partial seizures. The benefits of rufinamide include its pharmacokinetics, limited drug interactions, and lack of effect on cognitive function, but its use is limited by the rarity of LGS and the lack of comparative data with other antiepileptic agents.

Indirect comparison of clobazam and other therapies for Lennox-Gastaut syndrome

OBJECTIVE

In the absence of head-to-head trials, it is not feasible to make direct comparisons of antiepileptic therapies for the treatment of Lennox-Gastaut syndrome (LGS). We conducted indirect comparisons of the relative efficacies of clobazam, felbamate, lamotrigine, topiramate, and rufinamide as adjunctive treatments for LGS.

METHODS

Clinical studies of LGS patients were identified in a 2009 Cochrane review and by electronic database search. Five randomized controlled trials were included in this systematic review, which reports findings from indirect comparisons between clobazam and other approved adjunctive LGS therapies (felbamate, lamotrigine, topiramate, rufinamide) in the United States and Europe. As outcomes were not uniformly reported across studies, the primary efficacy endpoint from each trial was transformed into Cohen's d effect size, to facilitate indirect comparisons. Typical interpretations of Cohen's d results are as follows: d < 0.2, change not detectable; 0.2 ≤ d < 0.5, small change; 0.5 ≤ d < 0.8, moderate change; and 0.8 ≤ d, large change.

RESULTS

High-dosage clobazam (1.0 mg/kg/day) was found to have the strongest treatment effect vs placebo (effect size 0.80), with moderate effects (effect sizes >0.50) for medium-dosage clobazam (0.5 mg/kg/day) and rufinamide. Felbamate, lamotrigine, and topiramate had low effect sizes. Indirect comparisons of numbers of total seizures and tonic-atonic seizures ('drop attacks') demonstrated superiority of both clobazam dosages over all comparators.

CONCLUSIONS

High- and medium-dosage clobazam was estimated to be more efficacious than other LGS treatments. Our analysis relied on published data and could not draw on direct head-to-head data of clobazam with alternatives. Further comparative research is ongoing to assess the usefulness of clobazam for LGS.