• Clinical trial;
  • Antiepileptic drugs;
  • Absence seizures;
  • Myoclonic seizures;
  • Tonic–clonic seizures;
  • Idiopathic generalized epilepsy


Purpose:  To evaluate the long-term efficacy and tolerability of adjunctive levetiracetam (LEV) in patients with uncontrolled idiopathic generalized epilepsy (IGE).

Methods:  This phase III, open-label, long-term, follow-up study (N167; NCT00150748) enrolled patients (4 to <65 years) with primary generalized seizures (tonic–clonic, myoclonic, absence). Patients received adjunctive LEV at individualized doses (1,000–4,000 mg/day; 20–80 mg/kg/day for children/adolescents weighing <50 kg). Efficacy results are reported for all seizure types [intention-to-treat (ITT) population, N = 217] and subpopulations with tonic–clonic (n = 152), myoclonic (n = 121), and/or absence (n = 70) seizures at baseline.

Key Findings:  One hundred twenty-five (57.6%) of 217 patients were still receiving treatment at the end of the study. Mean (standard deviation, SD) LEV dose was 2,917.5 (562.9) mg/day. Median (Q1–Q3) exposure to LEV was 2.1 (1.5–2.8) years, and the maximum duration was 4.6 years. Most patients were taking one (124/217, 57.1%) or ≥2 (92/217, 42.4%) concomitant antiepileptic drugs (AEDs). Seizure freedom of ≥6 months (all seizure types; primary efficacy end point) was achieved by 122 (56.2%) of 217 patients, and 49 (22.6%) of 217 patients had complete seizure freedom. Seizure freedom of ≥6 months from tonic–clonic, myoclonic, and absence seizures was achieved by 95 (62.5%) of 152, 75 (62.0%) of 121, and 44 (62.9%) of 70 patients, respectively. Mean (SD) maximum seizure freedom duration was 371.7 (352.4) days. At least one treatment-emergent adverse event (TEAE) was reported by 165 (76%) of 217 patients; most TEAEs were mild/moderate in severity, with no indication of an increased incidence over time. Seventeen (7.8%) of 217 patients discontinued medication because of TEAEs. The most common psychiatric TEAEs were depression (16/217, 7.4%), insomnia (9/217, 4.1%), nervousness (8/217, 3.7%), and anxiety (7/217, 3.2%).

Significance:  Adjunctive LEV (range 1,000–4,000 mg/day) demonstrated efficacy as a long-term treatment for primary generalized seizures in children, adolescents, and adults with IGE, and was well tolerated.