Composition: Oxcarbazepine 150mg, 300mg and 600mg.
Presentation: Film-coated, yellow tablets.
Action: Anti-epileptic agent. Activity primarily exerted through its metabolite (the monohydroxy derivative, MHD).
Indications: Treatment of partial seizures with or without secondarily generalised tonic-clonic seizures. For use as monotherapy or adjunctive therapy in adults and childen of six years and above.
Contraindications: Hypersensitivity to active substance or any excipients. Breast-feeding.
Dosage and administration: Adults, monotherapy and adjunctive therapy, starting dose 600mg/day (8-10mg/kg/day), in two divided doses. Dose may be increased by a maximum of 600mg/day increments at approximately weekly intervals to achieve desired clinical response. Therapeutic effects are seen at doses between 600mg/day and 2,400mg/day.
Elderly, dose adjustment recommended in patients with compromised renal function.
Mild to moderate hepatic impairment, no dosage adjustment required. Oxcarbazepine has not been studied in patients with severe hepatic impairment.
Renal impairment (creatinine clearance less than 30ml/min), start at half usual dose (300mg/day) increasing in at least weekly intervals.
Pregnancy, data indicate that oxcarbazepine may cause serious birth defects. See SPC for details.
Children aged six years and above, in monotherapy and adjunctive therapy, starting dose of 8-10mg/kg/day, in two divided doses. Dose may be increased by a maximum of 10mg/kg/day increments at approximately weekly intervals to a maximum of 46mg/kg/day.
When other anti-epileptic drugs are replaced by oxcarbazepine, the concomitant anti-epileptic dose should be reduced gradually when starting oxcarbazepine. In adjunctive therapy, as the total anti-epileptic drug load is increased the concomitant anti-epileptic dose may need to be reduced and/or oxcarbazepine dose increased more slowly.
Overdosage: Symptoms of overdose include somnolence, dizziness, nausea, vomiting, hyperkinesia, hyponatraemia, ataxia and nystagmus. No specific antidote. Gastric lavage and/or administration of activated charcoal should be considered.
Precautions: Approximately 25-30 per cent of patients who have experienced hypersensitivity to carbamazepine may experience such reactions with oxcarbazepine. Hypersensitivity reactions may also occur in patients without history of hypersensitivity to carbamazepine. If signs and symptoms suggest such reactions, oxcarbazepine should be withdrawn immediately.
In patients with pre-existing renal conditions associated with low sodium or in patients treated concomitantly with sodium-lowering drugs (eg, diuretics, desmopressin) as well as NSAIDs, serum sodium levels should be monitored (see SPC). Patients already taking oxcarbazepine and starting on sodium-lowering drugs should follow the same sodium checks.
Patients with cardiac insufficiency and secondary heart failure should have regular weight measurements to determine occurence of fluid retention. Caution should be exercised if alcohol is taken. Patients should be advised that their physical and/or mental abilities required for operating machinery or driving a car might be impaired.
Drug interactions: Oxcarbazepine and MHD inhibit cytochrome CYP2C19. They also induce CYP3A4 and CYP3A5 which are responsible for the metabolism of dihydropyridine calcium antagonists and oral contraceptives. See SPC for details of interactions with other anti-epileptic drugs and with calcium antagonists. Concurrent use with hormonal contraceptives containing ethinyloestradiol and levonorgestrel may render the contraceptive ineffective. On theoretical grounds, concomitant use of MAOIs is not recommended. Combination of lithium and oxcarbazepine might cause enhanced neurotoxicity.
Side effects: Effects seen in 10 per cent of patients include fatigue, dizziness, headache, somnolence, nausea, vomiting, diplopia. Effects seen in 1 to 10 per cent of patients include asthenia, agitation, amnesia, apathy, impaired concentration, ataxia, confusion, depression, emotional lability (eg, nervousness), nystagmus, tremor, constipation, diarrhoea, abdominal pain, hyponatraemia, acne, alopecia, rash, vertigo, vision disorders (eg, blurred vision).
Net price: 150mg 50 £10, 300mg 50 £20, 600mg 50 £40.
Supplier: Novartis Pharmaceuticals UK Ltd, Frimley Business Park, Frimley, Camberley, Surrey GU16 5SG. Tel 01276 692255, fax 01276 692508.
Legal class: POM.