[Oxcarbazepine in the treatment of epilepsy]

Oxcarbazepine (OXC; Timox) is a new antiepileptic drug (AED) chemically related to carbamazepine (CBZ), with comparable efficacy but superior safety according to controlled clinical trials. In a prospective, post-marketing surveillance (PMS) study the efficacy and tolerability of OXC were investigated under conditions of daily routine practice.

The treatment of 1385 male and female epilepsy patients aged between 1 month and 94 years, who were newly stabilized on OXC or changed over from another AED, was documented in 362 centers over a period of 8 weeks. Efficacy and tolerability were assessed by documenting the frequency of seizures and adverse drug reactions (ADRs) and by global efficacy and tolerability ratings obtained from the patients and investigators.

Before the PMS study, 688/1335 patients (49.7 %) had received pre-treatment with CBZ, 342 (24.7 %) had received another AED and 335 (25.6 %) had had no AED pre-treatment (initial OXC monotherapy). In 161 patients pre-treated with CBZ (23,4 % of 688) an immediate (overnight) switch to OXC was performed while most others were switched during a titration phase. Of the patients with CBZ pre-treatment 21 % were switched to OXC at the recommended dose ratio of 1 : 1.4 - 1 : 1.6 (CBZ : OXC) while roughly 60 % were changed to OXC with a lower ratio. In the total sample the median OXC maintenance dose was 900 mg/day. During treatment with OXC the frequency of seizures per 4 weeks decreased by an average of 76 % in comparison to a retrospective pre-phase. 74 % of the patients showed an improved seizure situation, and 40.5 % became seizure-free under OXC (patients with initial monotherapy became seizure-free in 62 % of the cases). 71 % of the patients showed a reduction of their seizure frequency versus baseline by > or = 50 %. ADRs were reported in 10,8 % of the participants (incidence: 1 in 459 days of exposition to OXC; overnight switching from CBZ to OXC: 1 event in 1284 days). Only 2.5 % of the patients terminated OXC administration due to ADRs while 92 % continued treatment with OXC beyond the end of the study.

The results underline the high antiepileptic efficacy and good tolerability of OXC previously demonstrated in controlled clinical trials. When changing from CBZ to OXC, immediate (overnight) switching showed particularly favorable results.