Efficacy of Felbamate in Childhood Epileptic Encephalopathy (Lennox-Gastaut Syndrome)

Abstract

BACKGROUND: The Lennox-Gastaut syndrome is a childhood disorder characterized by multiple types of seizures, mental retardation, characteristic electroencephalographic abnormalities, and resistance to standard antiepileptic drugs. Felbamate is an investigational antiepileptic drug with a preclinical profile that suggests it would be effective in patients with multiple types of seizures. In controlled clinical trials, felbamate was superior to placebo in reducing the frequency of refractory partial-onset seizures. METHODS: We studied the efficacy of felbamate in 73 patients ranging in age from 4 to 36 years who had the Lennox-Gastaut syndrome. During a 28-day base-line phase, the patients received their usual antiepileptic therapies. At the end of this phase, felbamate or placebo was administered for 70 days in addition to the current antiepileptic medications. The dosage of felbamate was titrated during the first 14 days of the treatment phase to a maximum of 45 mg per kilogram of body weight per day or 3600 mg per day, whichever was less. The primary efficacy variables were the total number of seizures counted during a four-hour period of video recording, parents' or guardians' global evaluations of the patients' quality of life, and the total number of atonic seizures, as reported by parents or guardians. RESULTS: The patients treated with felbamate had a 34 percent decrease in the frequency of atonic seizures, as compared with a 9 percent decrease in the patients who received placebo (P = 0.01). The felbamate-treated patients had a 19 percent decrease in the total frequency of seizures, as compared with a 4 percent increase in the placebo group (P = 0.002). The global-evaluation scores were significantly higher in the felbamate group than in the placebo group from day 49 to the end of the study. There were no significant differences in the frequency of seizures occurring during video monitoring, but there was a significant reduction (P = 0.017) in the number of tonic-clonic seizures during the maintenance period in the felbamate group. The types and frequency of side effects were similar in the two treatment groups. CONCLUSIONS: Felbamate is beneficial in patients with the Lennox-Gastaut syndrome.