Effects of the antidepressant drug viloxazine on oxcarbazepine and its hydroxylated metabolites in patients with epilepsy

The effects of Viloxazine (VLX, 100 mg b.i.d. for 10 days) on the steady-state plasma concentrations of Oxcarbazepine (OXC), its active metabolite 10,11-dihydro-10-hydroxy-carbazepine (MHD) and the corresponding diol (DHD) were studied in a randomized, double-blind cross-over placebo-controlled trial in 6 epileptic patients stabilized on a fixed dosage of OXC. Administration of VLX resulted in an 11% increase in the plasma concentration of MHD (p = 0.003) associated with a 31% fall in DHD levels (p = 0.0001). Plasma concentrations of unchanged OXC were unaffected by VLX. No changes in seizure frequency nor signs of drug toxicity were observed during the study. Although VLX may inhibit the conversion of MHD to the inactive diol, the interaction is unlikely to be of clinical significance.