Efficacy and tolerability of 1000-4000 mg per day of levetiracetam as add-on therapy in patients with refractory epilepsy.

The aim of this study was to determine the efficacy and tolerability of 1000-4000 mg/day of levetiracetam (LEV, Keppra) as add-on treatment for refractory epilepsy. This was a dose-escalation study of 29 patients with refractory epilepsy. Patients received placebo for 4 weeks (baseline) followed by levetiracetam 1000 and 2000 mg per day each for 2 weeks, and then 3000 and 4000 mg per day each for 4 weeks. Primary efficacy was assessed by seizure frequency (number/week). Tolerability was assessed by adverse events, laboratory parameters, clinical evaluations, and electrocardiogram. All the study periods were completed by 27 of the 29 patients. A substantially lower median seizure frequency was observed at all levetiracetam dosing periods (1000 mg per day, 1.0 seizures per week; 2000 mg per day, 1.5 seizures per week; 3000 mg per day, 1.0 seizures per week; 4000 mg per day, 0.75 seizures per week) compared with the placebo treatment (2.06 seizures per week). In addition, 22-33% of these patients were seizure free during treatment with levetiracetam compared with only 14% with placebo. Levetiracetam was well tolerated. The most common adverse events were somnolence and asthenia; frequency and severity increased with increasing doses of levetiracetam. Levetiracetam in doses from 1000 to 4000 mg per day is effective. Somnolence and asthenia were more frequent with the highest dose, suggesting that 4000 mg per day may be the upper limit in some patients, although individual susceptibility to somnolence was variable.