Clinical monitoring during carbamazepine slow-release, once-daily monotherapy

Forty-eight patients with complex partial and/or tonic-clonic seizures were treated with an 8 p.m. single dose of carbamazepine slow release (CBZ-SR) monotherapy. The steady-state serum level profiles of carbamazepine (CBZ) and its metabolites CBZ-10,11-epoxide (CBZE) and 10,11-dihydro-CBZ-10,11-diole (CBZD) during 24 h in 21 of 48 patients treated with daily single doses of 8.4 (+/- 2.4) mg/kg body weight CBZ-SR were determined by a high-performance liquid chromatography procedure. The 8 a.m. CBZ levels correlated very well with the mean CBZ levels of the 24-h profile. Unlike CBZD, the individual 24-h mean CBZE levels also correlated well with the respective CBZ levels (CBZE = 14.2% +/- 2.9 of CBZ). Increasing CBZ-SR doses does not result in a proportional increase of CBZ levels. Clinical efficacy of changing from CBZ standard tablets under mono- or combination therapy or from therapy with other antiepileptic drugs to once-daily evening CBZ-SR monotherapy or commencement CBZ-SR therapy in previously untreated patients was monitored in 35 of 48 patients for a period of 8 months to 2 years. Complete seizure control was observed in 51% of patients and more than 75% reduction of seizure frequency in 14%. Eight of 11 previously untreated patients became seizure free. With change from CBZ monotherapy to CBZ-SR single-dose therapy, five of six patients became seizure free. Changing from other therapeutic regimens to CBZ-SR once-daily evening monotherapy was less successful.