Topiramate monotherapy in the treatment of newly or recently diagnosed epilepsy

The efficacy of topiramate (TPM) as an adjunctive treatment for epilepsy has been established in placebo-controlled clinical trials. Clinical trials of antiepileptic monotherapy usually evaluate low and high doses of study drug or compare study drug with another active agent.

This article reviews available evidence for the use of TPM as monotherapy in patients with newly or recently diagnosed epilepsy.

A search of MEDLINE, EMBASE, BIOSIS, SCISEARCH, and the Cochrane Database of Systematic Reviews (all years) for reports of controlled trials of TPM monotherapy in patients with recently diagnosed (within the previous 3 years) epilepsy was conducted in January 2008 using the terms topiramate, epilepsy, newly diagnosed, recently diagnosed, and monotherapy. Identified trials were included in the review if they were published in peer-reviewed journals and enrolled > or = 20 patients.

Three randomized, double-blind, controlled trials met the criteria for inclusion in the review. In a comparison of TPM 50 and 500 mg/d, the higher dose was associated with significantly greater freedom from seizures at 6 months compared with the lower dose (54% vs 39%, respectively; P = 0.02). The time to first seizure was significantly associated with mean plasma TPM concentrations (P = 0.015). In a comparison of TPM 50 and 400 mg/d, the time to first seizure was significantly longer with the higher dose compared with the lower dose (P<0.001, Kaplan-Meier analysis), and the probability of 12-month seizure freedom was significantly higher (76% vs 59%, respectively; P = 0.001). Again, the time to first seizure was significantly associated with mean plasma TPM concentrations (P = 0.029). In a comparative study of TPM 100 and 200 mg/d, carbamazepine 600 mg/d, and valproate 1250 mg/d, there was no significant difference in rates of 6-month seizure freedom with TPM 100 and 200 mg/d (49% and 44%, respectively), carbamazepine (44%), and valproate (44%). Adverse events in the 3 studies were similar between TPM dose groups, although the incidence generally increased with increasing doses, occurred early in treatment, and decreased with prolonged therapy. In a pooled analysis of the 3 trials, the most commonly occurring adverse events during dose titration were paresthesia (25%), fatigue (16%), dizziness (13%), somnolence (13%), and nausea (10%); the most frequent adverse events during maintenance therapy were headache (20%), decreased appetite (11%), and weight loss (11%).

In the 3 studies reviewed, TPM monotherapy was effective and generally well tolerated in patients with newly diagnosed epilepsy.