Oxcarbazepine and adverse events: impact of age, dosage, metabolite serum concentrations and concomitant antiepileptic therapy

The aim of this study was to investigate the relationships between oxcarbazepine (OXC) dosage, metabolite mono-hydroxy-derivative (MHD) serum concentrations, number of concomitant antiepileptic drugs, age and incidence of adverse events (AEs) in epileptic patients. A retrospective analysis was conducted of 414 consecutive epileptic patients on OXC alone or added-on to previous therapy. The sample was collected from the period 2001 to 2006. Statistical analysis was performed in two groups: with and without AEs. Eighty-seven patients (21%) experienced at least one AE. The most frequent was hyponatremia, reported in 9.2%. OXC was discontinued because of AEs in 27 cases. There were no important differences between patients with and without AEs, except for age (p=0.04). The categorization of patients into three different age ranges,20, 20-59 and (3)60 years, disclosed that the risk of AEs is notably lower in young (20 years) and adult (20-59 years) patients (OR 0.46 and 0.51, respectively). In particular, the patients who experienced hyponatremia were significantly older than those who did not (p=0.0045). The other variables showed no major changes according to age. The incidence of major AEs during OXC treatment, leading to withdrawal, was found to be low and influenced by age, but not by OXC dosage, MHD concentrations or number of concomitant antiepileptic drugs.