Levetiracetam: a new therapeutic option for refractory epilepsy.

Levetiracetam (LEV) is the most recently licensed antiepileptic drug (AED) for adjunctive therapy of partial seizures. Its mechanism of action is uncertain but it exhibits a unique profile of anticonvulsant activity in models of chronic epilepsy. Three randomised, double-blind, placebo-controlled trials enrolling 904 patients with refractory partial epilepsy have demonstrated the efficacy of LEV as adjunctive therapy, with a responder rate (> or = 50% reduction in seizure frequency) of 28-41%. Long-term efficacy studies suggest retention rates of 60% after one year, with 13% of patients seizure-free for six months of the study and 8% seizure-free for one year. Adverse effects of LEV, including somnolence, lethargy and dizziness, were generally mild and the frequency of incidents was not significantly different between the active treatment and placebo groups in clinical trials. LEV has no clinically significant pharmacokinetic interactions (PKI) with other AEDs, or with commonly prescribed medications. Preliminary data suggest that LEV has efficacy in primary generalised epilepsy and further randomised trials are under way. The combination of potent antiepileptic properties with a relatively mild adverse effect profile makes LEV an attractive adjunctive therapy for partial seizures.