Gabapentin and lamotrigine: novel antiepileptic drugs

The pharmacokinetics, efficacy, and adverse effects of gabapentin and lamotrigine, two new antiepileptic drugs (AEDs), are reviewed. Gabapentin and lamotrigine are promising advances in the treatment of epilepsy, which has not been satisfactorily controlled by available agents in 25-41% of patients. Gabapentin is chemically similar to gamma-aminobutyric acid, but it is able to pass into the central nervous system. It is effective for the treatment of partial-onset seizures that are refractory to other AEDs. It has no known drug-drug interactions and a relatively benign adverse effect profile, but its short half-life necessitates at least thrice-daily dosing. Lamotrigine is structurally unrelated to the other available AEDs. Its role is currently limited to add-on therapy in patients with partial seizures, with or without secondary generalization, that are resistant to current treatment. The efficacy of lamotrigine in patients with primary generalized tonic-clonic seizures, absence seizures, and Lennox-Gastaut syndrome remains to be validated. The adverse effect profile also remains to be determined. A rash may appear in up to 5% of patients, possibly necessitating discontinuation of the drug. Although lamotrigine does not seem to affect the pharmacokinetics of the other AEDs, the other AEDs affect lamotrigine pharmacokinetics. Lamotrigine can be given once or twice daily. Gabapentin and lamotrigine may be useful in treating patients whose epilepsy is not controlled by other available AEDs; however, further research is needed to confirm their roles in epilepsy treatment.