Abstracts

RATIONALE: Lamotrigine (LTG) is an effective antiepileptic drug in treating partial and generalized epilepsies. The aim of the present study was to evaluate the use of LTG in drug-resistant epilepsy as added to a pure sodium-blocking agent oxcarbazepine/slow-release carbamazepine (OXC/CBZ) or to a wider spectrum agent valproate (VPA). METHODS: LTG was added to 49 patients (mean age 37?12, range 16-58 years) with OXC/CBZ (8 OXC and 41 CBZ patients) and to 26 patients (mean age 39?18, range 12-73 years) with VPA therapy. Forty-eight OXC/CBZ and 18 VPA patients had partial epilepsy. In 1 OXC/CBZ and in 2 VPA patients the epilepsy was generalized. There were also 4 VPA patients with progressive myoclonic epilepsy and 2 with Lennox-Gastaut syndrome. Fourteen patients used OXC/CBZ and 9 VPA as monotherapy. Retention rate was used as outcome measure to evaluate both the overall efficacy and safety after 1,3 and 5 years of follow-up. RESULTS: After 1 year follow-up 43 (88%) OCX/CBZ and 23 (88%) VPA patients were still on LTG therapy. LTG had been stopped in 6 OCX/CBZ patients (lack of efficacy 3, non-compliance, nausea and vomiting, psychosis in 1 each) and in 3 VPA patients (noncompliance 2, lack of efficacy 1). The number of patients with marked seizure reduction did not differ significantly between study groups. Altogether 24 (49%) OCX/CBZ and 19 (73%) VPA patients had >50% reduction in seizure frequency (p=0.053). Over 75% reduction was achieved in 14 (29%) OCX/CBZ and in 11 (42%) VPA patients (p=0.304). Nine patients in both OCZ/CBZ (18%)and VPA (35%) groups were seizure-free (p=0.101). After 3 years 13 (65%) of the 20 OCX/CBZ and 5 (83%)of the 6 VPA patients had >50% seizure reduction. Five (25%) OCX/CBZ and 1 (17%) VPA patients were seizure-free. After 5 years 5 (56%) of the 9 OCX/CBZ patients had >50% seizure reduction, and 2 (22%) were seizure-free. All the 3 (100%) VPA patients had >75% seizure reduction, and 2 (67%) were seizure-free. CONCLUSIONS: LTG is effective and well tolerated as add-on therapy. In LTG-VPA therapy, the effect may come from complementary pharmacodynamic action. However, also patients with LTG-OCX/CBZ therapy seem to benefit from the synergy of drugs with similar modes of action.