Clinical administration of new antiepileptic drugs: An overview of safety and efficacy

Gabapentin, lamotrigine, tiagabine, topiramate, vigabatrin, and zonisamide are all administered as add-on therapy for treatment of patients with refractory epilepsy. To date, no comparative randomized trials have been performed that could potentially allow an evidence-based choice to be made between these antiepileptic drugs (AEDs). We report a series of meta-analyses of placebo-controlled, randomized add-on trials in patients with partial epilepsy. Results of these meta-analyses are compared, thus giving broad estimates of the comparative efficacy and tolerability of these AEDs. The efficacy outcome is the odds ratio for the number of patients with a greater than or equal to 50% reduction in seizure frequency. Reported side effects are also used as tolerability outcomes, and study withdrawal is used as a global outcome measure. Results are summarized as odds ratios with 95% confidence intervals (CIs). When each outcome is compared among drugs, the 95% CIs overlap. Therefore, no conclusive evidence of a difference in efficacy or tolerability between these AEDs was derived, even though the apparently most effective agent (topiramate) may be twice as effective as the apparently least effective agent (lamotrigine). Comparative randomized studies are needed to further evaluate these drugs.