Gabapentin and lamotrigine are not alternative first-line antiepileptic drugs at present. The use of both drugs is limited to add-on therapy in patients with refractory partial seizures. Nonetheless, the reductions in seizure frequency gained in these difficult-to-treat patients are worthwhile.
Preliminary data in other types of epilepsy are encouraging but require confirmation. Lamotrigine appears to have the wider spectrum of activity at present.
Both drugs appear relatively well tolerated, although long term and comparative data are lacking.
Neither drug affects the metabolism of oral contraceptives, and gabapentin has a low risk of other interactions with other drugs. However, this may be of limited significance as long as the drugs are used only as add-on therapy.
Of the 2 drugs, gabapentin may be the easiest to prescribe since it requires dosage adjustment only in patients with renal impairment. Blood concentrations of lamotrigine are profoundly affected by concomitant antiepileptic therapy, although it does not influence concentrations of the interacting drugs. Thus, when prescribing lamotrigine, physicians must adjust the dosage according to concomitant therapy.