Tolerability and Effects on Quality of Life of Twice-Daily Extended-Release Carbamazepine in Adults with Seizure Disorders: An Open-Label, 12- To 36-Month Continuation Study

Background: An earlier 6-month, multicenter, open-label study in patients with complex partial seizures found that a switch from multiple daily doses of conventional carbamazepine (CBZ) to twice-daily CBZ extended-release capsules (CBZ-ERC) was well tolerated, with maintenance of seizure control over the study period and significant improvements in quality of life (P < 0.001). Objective: The goal of the present study was to assess the tolerability and effects on quality of life of twice-daily CBZ-ERC over the longer term in patients with seizure disorders. Methods: This was a multicenter, open-label assessment of the long-term (12-36 months) tolerability and quality-of-life effects of twice-daily CBZ-ERC given at a daily dose equivalent to the daily dose of CBZ taken before study entry. The regimen could be adjusted as clinically indicated up to a daily dose of 1600 mg. Patients could receive up to 2 other antiepileptic drugs during the study. Results: One hundred eighteen patients were enrolled. In patients completing ≥12 months of study therapy, a significant decrease in the highest mean 2-day frequency of generalized tonic-clonic seizures was observed over the first 12 months (P = 0.005). The significant improvements in quality of life achieved in the earlier study were maintained during the present study. Of 37 patients who were discontinued from the study 9 met criteria mandating withdrawal from the study due to exacerbation of seizures. Three patients were discontinued from the study for adverse events judged to be unrelated to study drug. Low incidences of rash (3.4%) and weight gain (0.8%) were reported. Conclusions: In this population of adults with seizure disorders, CBZ-ERC twice daily was well tolerated during 12 to 36 months of open-label treatment, with no increase in seizure frequency or decrease in quality of life.