Oxcarbazepine: an update of its efficacy in the management of epilepsy

Abstract

Oxcarbazepine (10,11-dihydro-10-oxo-5H-dibenz[b,f]azepine-5-carboxamide) is a 10-keto analogue of carbamazepine with anticonvulsant activity. In newly diagnosed adult patients, oxcarbazepine monotherapy is as effective as phenytoin and vaiproic acid at reducing generalised tonic-clonic and partial seizure frequency. Furthermore, oxcarbazepine 2400 mg/day as monotherapy has also proved effective in the treatment of refractory partial seizures in adult patients. Oxcarbazepine 600, 1200 and 2400 mg/day as adjunctive therapy significantly reduced seizure frequency compared with placebo in 692 patients with refractory partial seizures. The efficacy of oxcarbazepine monotherapy is similar to that of phenytoin in the treatment of children and adolescents with newly diagnosed partial or generalised tonic-clonic seizures. Additionally, adjunctive therapy with oxcarbazepine was significantly more effective than placebo at reducing seizure frequency in children and adolescents with refractory partial seizures. The most commonly reported adverse events associated with oxcarbazepine monotherapy and/or adjunctive therapy in adults and/or children are somnolence, dizziness, headache, nausea and vomiting. Oxcarbazepine monotherapy is better tolerated than phenytoin (in both adults and children) and valproic acid (in adults), and although 75 to 90% of adult patients in 5 recent monotherapy studies reported adverse events while receiving oxcarbazepine, <8% withdrew from treatment because of them. Acute hyponatraemia, although usually asymptomatic, develops in 2.7% of patients treated with oxcarbazepine. Adverse events most likely to resolve upon switching to oxcarbazepine therapy from treatment with carbamazepine are undetermined skin reactions (rashes, pruritus, eczema), allergic reactions and a combination of malaise, dizziness and headache. Although oxcarbazepine does have a clinically significant interaction with some drugs (e.g. phenytoin and oral contraceptives), it has a lower propensity for interactions than older antiepileptic drugs (AEDs) because its major metabolic pathway is mediated by noninducible enzymes.

Conclusion: Oxcarbazepine as monotherapy is a viable alternative to established AEDs in the treatment of partial and generalised tonic-clonic seizures in adults and children. Furthermore, it is also effective as adjunctive therapy in the treatment of refractory partial seizures in both age groups. In addition, the drug is tolerated better than the older, established AEDs, and has a lower potential for drug interactions. These attributes make oxcarbazepine an effective component in the initial treatment of newly diagnosed partial and generalised tonic-clonic seizures, and also as an adjunct for medically intractable partial seizures in both adults and children.