Topiramate is approved for treating epilepsy in combination with other epilepsy drugs, but not approved for treating epilepsy as sole treatment or in recently diagnosed epilepsy characterized by partial-onset seizures. This is a randomized, double-blind, parallel-group, multicenter study to compare the safety and effectiveness of two doses of topiramate as monotherapy in pediatric and adult patients with newly diagnosed (within 3 months) or recurrent epilepsy (partial-onset or primary generalized tonic-clonic). The study consists of 4 phases: Baseline (assessment of seizure frequency and other eligibility), Open-Treatment (all patients receive 25 milligrams\[mg\]/day of topiramate for 7 days), Core Double-Blind Phase (patients are randomized to receive either their assigned dose of topiramate of 50mg/day or 400mg/day, or maximum tolerated dose, and then remain, if possible, on that dose for the duration of the double-blind phase; they continue to receive the medication until they experience the first seizure or until 6 months after the last patient is enrolled), and Long-Term Extension Phase (patients continue to receive the medication at maximum tolerated dose, which may be adjusted according to individual tolerability and effectiveness, until either the patient withdraws or the sponsor terminates the study). The study hypothesis is that topiramate will be effective in the treatment of newly diagnosed or recurrent epilepsy in dose-dependent manner. Topiramate tablets (25 milligrams\[mg\]) daily by mouth in once-daily regimen during the 7-day Open-Treatment Phase; topiramate twice daily for total of 50mg/day or 400mg/day during the Double-Blind Phase.
