Lamotrigine as add-on therapy in adult patients with refractory epilepsy

Lamotrigine (LTG), one of the newly developed antiepileptic drugs, is efficacious in treating both partial and generalized seizure disorders including Lennox-Gastaut syndrome. Its effect as an add-on therapy was evaluated in 41 adult Chinese patients with refractory epilepsy. Five of the patients were Lennox-Gastaut syndrome and 36 patients had partial epilepsy.

We started LTG at 25 mg or 50 mg per day, respectively, depending on whether the patients were simultaneously taking valproate (VPA) or not. Then, LTG was increased in steps to maximal dosage (200 mg or 400 mg per day) within seven weeks and maintained for three months while pre-existing antiepileptic drugs remained unchanged. The efficacy of LTG therapy was assessed by the reduction in the overall seizure frequency. Hematological and biochemical parameters were checked before and after the trial in all patients.

In all, 38 patients completed the trial. Twenty-two patients (57.9%) had > or = 50% reduction in seizure frequency, including four patients with Lennox-Gastaut syndrome and 18 patients with partial seizures. Among the patients with partial epilepsy, there was no significant difference in the efficacy of LTG whether the seizures were of temporal or extra-temporal origin (p = 0.577). In addition, the efficacy was not determined by the concomitant use of VPA (p = 0.189). Thirteen patients (31.7%) complained of adverse experiences, usually mild and dose-dependent. LTG had to be discontinued in only two patients (4.9%) due to severe side effects. The change in blood cell counts and biochemistry profiles was not significant in any of the patients.

We conclude that LTG is an efficacious and safe antiepileptic drug for add-on therapy in adult patients with refractory epilepsy.