Oxcarbazepine

eMC §4.2 (Oxcarbazepine 300 mg tablets). MONOTHERAPY: controlled trials in patients not currently on antiepileptic medicines showed 1,200 mg/day to be an effective dose; 2,400 mg/day has been shown to be effective in more refractory patients converted from other antiepileptics to oxcarbazepine monotherapy. In a controlled hospital setting, dose increases up to 2,400 mg/day have been achieved over 48 hours. ADJUNCTIVE THERAPY: daily doses of 600 to 2,400 mg/day were effective in a controlled trial, although most patients could not tolerate 2,400 mg/day without reducing concomitant antiepileptics, mainly because of CNS-related adverse events; daily doses above 2,400 mg/day have not been studied systematically. As the total antiepileptic load increases in adjunctive therapy, the dose of the concomitant antiepileptic(s) may need to be reduced and/or the oxcarbazepine dose increased more slowly. When replacing other antiepileptics, reduce the concomitant antiepileptic dose gradually on initiation of oxcarbazepine. THERAPEUTIC DRUG MONITORING: the therapeutic effect is primarily exerted through the active metabolite, the 10-monohydroxy derivative (MHD). Routine plasma level monitoring is not warranted, but may be useful where altered MHD clearance is expected; in such situations the dose may be adjusted (based on plasma levels measured 2-4 hours post dose) to maintain peak MHD plasma levels below 35 mg/L. ELDERLY (65 years and above): no special dose recommendations are necessary because therapeutic doses are individually adjusted, but dosage adjustment is recommended in elderly patients with renal impairment (creatinine clearance less than 30 mL/min), and close monitoring of sodium levels is required in patients at risk of hyponatraemia. HEPATIC IMPAIRMENT: no dosage adjustment for mild to moderate impairment; not studied in severe hepatic impairment, so caution should be exercised. Lower initiation doses than those above may be considered where appropriate for any age group. US LABELLING DIFFERENCE (openFDA, oxcarbazepine oral suspension, Novadoz Pharmaceuticals, label date 2024-11-18): the US label caps adjunctive therapy in adults at a recommended 1,200 mg/day; conversion to monotherapy targets 2,400 mg/day with concomitant antiepileptics withdrawn over 3 to 6 weeks; initiation of monotherapy uses increments of 300 mg/day every third day to 1,200 mg/day.

eMC §4.2 paediatric population, stated as a range so no single per-kg figure is given: initiate mono- or adjunctive therapy at 8-10 mg/kg/day in 2 divided doses. In adjunctive therapy trials a maintenance dose of 30-46 mg/kg/day, achieved over two weeks, was effective and well tolerated in children, with therapeutic effects at a median maintenance dose of approximately 30 mg/kg/day. If clinically indicated the dose may be increased by a maximum of 10 mg/kg/day at approximately weekly intervals to a maximum of 46 mg/kg/day. Recommended for use in children of 6 years of age and above; NOT recommended in children under 6 years since safety and efficacy have not been adequately demonstrated (safety and efficacy were evaluated in approximately 230 children aged under 6 years, down to 1 month). An oral suspension is available for children who cannot swallow tablets or where the required dose cannot be given as tablets. The US label differs and permits younger use - adjunctive therapy from 2 years (8-10 mg/kg/day, generally not to exceed 600 mg/day, twice daily; weight-banded targets over 2 weeks of 900 mg/day for 20-29 kg, 1,200 mg/day for 29.1-39 kg and 1,800 mg/day above 39 kg; for ages 2 to under 4 years and under 20 kg a starting dose of 16-20 mg/kg/day may be considered, with the maximum maintenance dose reached over 2 to 4 weeks and not exceeding 60 mg/kg/day) and monotherapy from 4 years. Verify all under-18 dosing against a children's formulary before prescribing.