Tolerance of high dosage carbamazepine monotherapy in treatment of epilepsy

Abstract

We examined whether high dose carbamazepine (CBZ) monotherapy (CBZ serum levels > 9 mg/l) is well tolerated. Forty-one patients with localisation-related epilepsy were enrolled. They received high dose monotherapy either from the time of recruitment (30/41), or their CBZ treatment was pushed into the high dose range (11/41) during the observation period (mean 145 days). CBZ and CBZ metabolite serum levels, full blood counts, liver function tests, electrolytes were measured in addition to clinical assessments. The mean daily CBZ dose was 1515 mg (median 1500, range 600-3600 mg). Mean CBZ serum level was 11.1 mg/l (median 11.1, range 5.3-16.4 mg/l). Eleven of 41 patients (26.8%) reported side effects (mean serum level 11.4, median 11.6, range 8.7-13.7 mg/l), but side effects were intolerable in only five patients so that the CBZ dose had to be reduced (mean CBZ serum level 11.4, median 11.6, range 8.7-13.7 mg/l). The total daily CBZ dose but not CBZ or CBZ metabolite levels were correlated with side effects. No treatment changes had to be undertaken because of abnormal laboratory parameters. High dose CBZ anticonvulsant monotherapy is well tolerated.