Randomized, Controlled, Dose-ranging Trial of Carisbamate for Partial-onset Seizures

Objective: To evaluate the efficacy, safety, and tolerability of carisbamate (CRS), an investigational drug, as adjunctive treatment for partial-onset seizures in adults.

Methods: A randomized, double-blind, placebo-controlled, multicenter, dose-ranging study was conducted in 12 countries. Patients counted seizures during an 8-week baseline period, and then, if eligible, entered a double-blind phase consisting of a 4-week dose-titration period (target CRS doses: 100, 300, 800, or 1,600 mg/d or placebo in two divided doses) and a 12-week maintenance period. The primary efficacy variable was percent reduction in partial-onset seizure frequency during the double-blind phase compared with pretreatment baseline. Safety data and responder rates were also assessed.

Results: Five hundred thirty-seven patients were randomized, and 82% completed the study. In the intent-to-treat population (n = 533), CRS at doses of > or =300 mg/d (p < or = 0.006) reduced the frequency of partial-onset seizures vs placebo: 6% (placebo) vs 24% (300 mg/d), 21% (800 mg/d), and 29% (1,600 mg/d) for CRS. Adverse events consisted primarily of CNS effects, and led to discontinuation of drug in 8% of the placebo group vs 5% (100 mg/d), 6% (300 mg/d), 12% (800 mg/d), and 19% (1,600 mg/d) of the CRS groups.

Conclusions: Carisbamate at doses of 300, 800, and 1,600 mg/d was effective as adjunctive therapy for reducing the frequency of partial-onset seizures.