Levetiracetam. A review of its adjunctive use in the management of partial onset seizures.

UNLABELLED: Levetiracetam, the S-enantiomer of alpha-ethyl-2-oxo-1-pyrollidine acetamide, is approved for use as adjunctive therapy in adult patients with partial onset seizures. Oral levetiracetam 1000, 2000 and 3000 mg/day administered as adjunctive therapy for up to 18 weeks significantly increased responder rates and reduced seizure frequency compared with placebo in 3 well designed pivotal trials in adults with treatment-refractory partial seizures with or without secondary generalisation. Levetiracetam 3000 mg/day also significantly increased the number of seizure-free patients, but the effects of levetiracetam 1000 and 2000 mg/day on this end-point were unclear. Effects on seizure severity were not assessed in these trials. Although not yet approved as monotherapy or for use in paediatric patients, efficacy was observed with levetiracetam 3000 mg/day as monotherapy in adult patients with refractory partial seizures with or without secondary generalisation and with the 10 to 40 mg/kg/day dosage as adjunctive therapy in children with refractory partial seizures. However, these data are limited. Oral levetiracetam 1000, 2000 and 3000 mg/day as adjunctive therapy is generally well tolerated with an overall incidence of adverse events similar to that observed with placebo. The most commonly reported events in individual clinical trials were CNS-related and included somnolence, asthenia, headache and dizziness. Levetiracetam administered as adjunctive therapy does not appear to interact with other anticonvulsant drugs, and no clinically relevant interactions were observed between levetiracetam and digoxin, warfarin or probenecid; oral contraceptive protective efficacy was also not affected by levetiracetam.
CONCLUSIONS: Levetiracetam is a new anticonvulsant agent with a favourable tolerability profile and a low potential for drug interactions. It has shown efficacy as adjunctive therapy in patients with treatment-refractory partial onset seizures with or without secondary generalisation in clinical trials. Direct comparative trials with other anticonvulsant agents are not yet available, but placebo-controlled clinical evidence to date suggests that levetiracetam (1000, 2000 and 3000 mg/day) is a useful option as adjunctive therapy in patients with this subtype of epilepsy.