Clinical efficacy of topiramate as add-on therapy in refractory partial epilepsy: the European experience.

In three randomized, double-blind, placebo-controlled add-on European trials, target daily topiramate (TPM) dosages of 400, 600, and 800 mg/day (200, 300, and 400 mg bid) were evaluated in adults with refractory partial seizures with or without becoming secondarily generalized. Median reductions from baseline in monthly seizure rate were 41% with TPM 400 mg/day vs. 1% with placebo (n = 0.065), 46% with TPM 600 mg/day compared to -12% (a 12% increase) with placebo (p < or = 0.005), and 36% with TPM 800 mg/day versus -18% (an 18% increase) with placebo (p < 0.001). Differences between TPM and placebo with respect to percent responders (percent of patients demonstrating a 50% or greater reduction in seizures) significantly favored TPM (p < 0.05) at all three target dosages. Significant reductions in secondarily generalized tonic-clonic seizures compared to placebo were also observed with 400 mg/day (p = 0.002) and 800 mg/day (p < 0.05) of TPM. TPM appears to be a promising new antiepileptic drug for use as adjunctive therapy in adults with refractory partial epilepsy.