The Serum Levels and Side Effects of Single Oral Loading of Controlled-Release Carbamazepine

Kim, Byung Kun; Bae, Hee Joon; Jang, In Jin; Park, Seong Ho; Lee, Sang Kun

Abstract

BACKGROUND: Effective oral loading of carbamazepine (CBZ) is very important as it is the most often administered drug for partial and generalized seizures. The pharmacokinetics and tolerability of a single oral loading of controlled-release form of carbamazepine (CBZ-CR) were assessed in 38 adult patients at risk for seizure.
METHODS
CBZ-CR was administered to 38 adults (22 had had CBZ just before entry into the study and 16 had not) at a dosage of 20 mg/kg as a single loading. Side effects and serum levels of CBZ and CBZ-10,11-epoxide (CBZ-E) were evaluated at 0, 2, 4, 6, 8, 12, 18, 24 h after the loading. Correlations between the frequency of side effects and other parameters (maxium serum concentration : Cmax, time to maximum concentration Tmax and area under the concentration time curve (AUC) of CBZ and CBZ-E) were also assessed.
RESULTS
Mean CBZ serum levels (percentage of subjects with level > 4 Mg/ml shown in parenthesis) were 0.0 (0%), 3.2 (30%), 6.1 (79%), 7.2 (92%), 7.7 (95%), 7.7 (95%), 7.7 (95%) and 7.1 Mg/ml (95%) at 0, 2, 4, 6, 8, 12, 18 and 24 h after loading. Cmax and Tmax were 8.42 Mg/ml and 13.2 h respective-ly. Although side effects developed in 15 patients (39%), there were no significant neurotoxic side effects. The frequen-cy of the history of CBZ use was not different (p<0.05) in the two groups (one had side effects, another had not). Cmax, Tmax, and AUC of CBZ and CBZ-E were also not different (p<0.05).
CONCLUSIONS
A single oral loading dose of CBZ-CR provides therapeutic serum concentrations quickly (in most patients within 6h) and is well tolerated. Rapid loading with CBZ-CR appears to be a useful alternative for the management of patients with a high risk of seizures.