Long-term efficacy of levetiracetam for partial seizures

To obtain descriptive safety and efficacy data for long-term levetiracetam therapy and to allow patients benefiting from add-on levetiracetam to continue treatment until the drug was available commercially.

This long-term, noncomparative, open-label, follow-up study was conducted at 36 US sites. Patients with refractory partial epileptic seizures were eligible if they had benefited from add-on levetiracetam therapy in a previous study and wished to continue treatment. The levetiracetam dose was individualized over the range of 1,000-4,000 mg/day. Withdrawal of concomitant AEDs to allow levetiracetam monotherapy was permitted. Patients were evaluated every 12 weeks and followed for up to 4 years. Median total seizure frequency per week was the primary efficacy variable.

A total of 280 subjects, most of whom had refractory partial seizures with or without secondary generalization, were evaluated. Most were receiving either one (34.6%) or two (53.2%) concomitant antiepileptic drugs (AEDs) at entry. Overall, 199 (71.1%) subjects completed the study and 81 (28.9%) withdrew prematurely, most commonly due to loss or lack of efficacy or adverse events. The median total seizure frequency per week (0.7 at the selection visit) remained stable. The probability of being seizure-free during the first 12 weeks was 13.4% and 3.7% by week 216. Twenty-five (8.9%) subjects received levetiracetam monotherapy for at least 100 days. Levetiracetam was safe and well tolerated; the most common levetiracetam-related adverse events were dizziness (6.8%), convulsion (5.7%), and somnolence (5.0%).

Efficacy and safety were maintained during long-term levetiracetam treatment of refractory partial seizures.