Double-blind crossover comparison of Tegretol-XR and Tegretol in patients with epilepsy. The Tegretol OROS Osmotic Release Delivery System Study Group.

This multicenter, double-blind, crossover study compared Tegretol-XR and Tegretol tablets with respect to trough plasma carbamazepine (CBZ) concentrations, seizure control, tolerability, and safety. We randomized 96 patients with epilepsy to 56-day monotherapy with their usual daily CBZ dose administered as (1) Tegretol-XR 200-mg tablets every 12 hours plus placebo or (2) Tegretol 200-mg tablets three or four times daily plus placebo. Upon completion, patients immediately switched to the alternate treatment for 56 days. During the study, 98% of patients had plasma CBZ concentrations within the recommended therapeutic range during Tegretol-XR treatment and 97% did during Tegretol treatment. The seizure rate during treatment, compared with the baseline seizure rate, decreased in 26% of patients both during treatment with Tegretol-XR and during treatment with Tegretol, and it remained the same in 48% of patients during Tegretol-XR therapy and in 52% of patients during Tegretol therapy. We did not observe any pattern of change in seizure frequency. We switched patients on a milligram-per-milligram basis from multiple-daily-dose Tegretol to Tegretol-XR twice daily from one day to the next without reiterating the daily dose.