Objective: To evaluate the tolerability and efficacy of two titration rates for topiramate initiated as adjunctive therapy in adults with partial-onset seizures, with or without secondary generalization, in a multicenter, double-blindtrial.
Methods: After a two-week baseline phase, 188 patients were randomized to either a 50/50 titration schedule (initial dosage 50 mg/d increased in 50-mg/d increments at weekly intervals; n = 95) or to a 100/200 titration schedule (initial dosage 100 mg/d increased by 100-200 mg/d at weekly intervals; n = 93). The maximum dosage of 400 mg/d was therefore achieved in eight weeks or three weeks, respectively.
Results: Compared with the 100/200 titration rate, the 50/50 titration rate significantly reduced the cumulative incidence of treatment-emergent adverse events (TEAEs) leading to changes in topiramate therapy (ie., dosage reductions, interruptions or discontinuations of therapy) (p = 0.048) and significantly reduced treatment interruptions or withdrawals due to TEAEs (p = 0.040). Mild or moderate effects involving the central nervous system were the most frequent adverse events. At the final visit, therapeutic responses were comparable in the 50/50 and 100/200 titration groups: median percent seizure reduction was 42% vs. 33%, proportion of patients with 250% seizure reduction was 42% vs. 38%, and proportion of patients with no seizures during double-blind treatment was 14% vs. 10%, respectively. Seizure frequency was substantially reduced from baseline during topiramate titration. At day 22, with the 50/50 titration group receiving 150 mg/d and the 100/200 titration group receiving 400 mg/d, the mean percent seizure reduction was 51% and 54%, respectively.
Conclusions: Gradual initiation of topiramate therapy can significantly enhance patient tolerability without delaying therapeutic response.