Efficacy and safety of add-on divalproex sodium in the treatment of complex partial seizures. The M88-194 Study Group.

We studied the efficacy of divalproex sodium in patients with complex partial seizures taking concomitant carbamazepine or phenytoin as monotherapy. Patients were selected because of inadequate seizure control by current therapy. The primary efficacy measure was median reduction of seizure frequency during add-on treatment compared with baseline. A secondary measure was the percentage of patients achieving > or = 50% reduction in seizure frequency. In the intent-to-treat analysis (137 patients), divalproex-treated patients experienced a median reduction of 7.9 complex partial seizures per 8 weeks compared with 2.5 in the placebo group (p = 0.001). Also, 38% of divalproex-treated patients completed the study with a seizure reduction of > or = 50% compared with 19% receiving placebo (p = 0.011). Six divalproex- and one placebo-treated patient became free of complex partial seizures. We conclude that divalproex sodium is an effective drug for treating patients with complex partial seizures.