Efficacy of topiramate in adult patients with symptomatic epilepsy: an open-label, long-term, retrospective observation.

BACKGROUND: Topiramate is a newer generation antiepileptic drug with a wide range of antiepileptic efficacy as monotherapy or as adjunctive therapy, and which has shown positive activity in intractable epilepsy and newly diagnosed epilepsy. Topiramate has also been shown to exert good seizure control with a low incidence of adverse effects in brain tumour-associated epilepsy. However, there have been few reports on the efficacy of topiramate in the treatment of symptomatic epilepsy of varying aetiologies.
OBJECTIVE: The aim of the present study was to evaluate the efficacy of topiramate in the treatment of adult patients with symptomatic epilepsy of various aetiologies.
METHODS: This was an open-label, long-term, retrospective observation. 227 patients with symptomatic epilepsy (110 male, 117 female) were enrolled into this study. The underlying aetiologies included low-grade brain tumour, head trauma, cerebrovascular diseases, infection, diabetes mellitus, hydrocephalus and parasitosis. Topiramate was titrated up to a target dosage of 200 mg/day and maintained for at least 1 year. Response to topiramate was defined as > or = 50% reduction in seizure frequency compared with baseline. Seizure free was defined as no seizure occurring during 1 year of topiramate therapy.
RESULTS: 157 (69.2%) patients were responders and 124 (54.6%) patients were seizure free with topiramate administration. Responders by subgroup included 40 patients (74.0%) with low-grade brain tumour, 32 (55.2%) with trauma, 30 (90.9%) with cerebrovascular disease, 21 (55.3%) with infection, 18 (81.8%) with diabetes, 12 (85.7%) with parasitosis and 4 (50.0%) with hydrocephalus. The percentage of seizure-free patients by subgroup was 61.0% with brain tumours, 31.0% with trauma, 78.8% with cerebrovascular disease, 44.7% with infection, 59.0% with diabetes, 85.7% with parasitosis and 50.0% with hydrocephalus. The incidence of adverse effects was 36.1%. The most commonly reported adverse effects were weight loss, memory impairments, paraesthesia, headache and dizziness; most were mild to moderate in severity and transient. Sixty-eight (30.0%) patients withdrew from topiramate treatment in this study: topiramate was discontinued in 56 patients because of lack of efficacy and in 12 patients because of adverse effects. At the end of the study, 109 patients received topiramate monotherapy, including 52 newly diagnosed patients and 57 subjects who transferred to topiramate monotherapy successfully; another 118 patients received add-on topiramate therapy. The percentage of patients responding to topiramate was 85.3% in the monotherapy group and 54.2% in the topiramate add-on therapy group; the percentage of seizure-free patients was 68.8% in the topiramate monotherapy group and 41.5% in the topiramate add-on therapy group.
CONCLUSION: When administered either as a single drug or as an add-on drug, topiramate is effective and well tolerated in adult patients with symptomatic epilepsy of various aetiologies.