What is the recommended dosing for oxycarbamazepine (Oxtellar XR) in adults?

Oxcarbazepine (Oxtellar XR) Dosing in Adults

For adults, oxcarbazepine should be initiated at 600 mg/day divided twice daily, with dose increases of up to 600 mg/day at weekly intervals to reach the recommended maintenance dose of 1200 mg/day for adjunctive therapy or 2400 mg/day for monotherapy. 1

Initial Dosing Strategy

Adjunctive Therapy

• Start at 600 mg/day in two divided doses 1
• Increase by maximum of 600 mg/day at approximately weekly intervals 1
• Target maintenance dose: 1200 mg/day 1
• Doses above 1200 mg/day show somewhat greater effectiveness but are poorly tolerated due to CNS effects, particularly at 2400 mg/day 1

Conversion to Monotherapy

• Initiate oxcarbazepine at 600 mg/day (BID regimen) while simultaneously reducing concomitant antiepileptic drugs 1
• Withdraw concomitant AEDs completely over 3-6 weeks 1
• Reach maximum oxcarbazepine dose of 2400 mg/day over 2-4 weeks 1
• Increase by maximum 600 mg/day increments at weekly intervals 1

Initiation of Monotherapy (Drug-Naive Patients)

• Start at 600 mg/day in two divided doses 1
• Increase by 300 mg/day every third day to reach 1200 mg/day 1
• Maximum effective dose: 2400 mg/day 1

Alternative Rapid Titration Approach

For patients requiring faster titration, research supports a more aggressive schedule:

• Begin at 150 mg/day at night 2, 3
• Increase by 150 mg every 2-3 days until target dose of 900-1200 mg/day is reached 2, 3
• Alternatively, start with up to 600 mg/day and titrate with weekly increments up to 600 mg/day if necessary for seizure control 2, 3

Important Clinical Considerations

Monitoring Requirements

• Monitor concomitant AED plasma levels closely during titration, especially at oxcarbazepine doses >1200 mg/day 1
• Consider serum sodium monitoring in patients with renal disease, those taking diuretics/oral contraceptives/NSAIDs, or if symptoms of hyponatremia develop 3
• Hyponatremia (<125 mmol/L) develops in approximately 3% of patients during the first months of therapy 3

Drug Interactions

• Oxcarbazepine at doses >1200 mg may increase phenytoin levels by 40% and phenobarbital by 15% 4
• Carbamazepine, phenobarbital, and phenytoin reduce MHD (active metabolite) levels by 30-40% 4
• Oxcarbazepine decreases oral contraceptive hormone levels and may cause contraception failure 4

Renal Impairment

• In patients with creatinine clearance <30 mL/min, reduce dose by at least 50% and prolong titration period 4
• No dose adjustment needed for mild-to-moderate hepatic impairment 4

Administration

• Can be taken with or without food 1
• Oxcarbazepine oral suspension and film-coated tablets are interchangeable at equal doses 1

Common Pitfalls to Avoid

• Do not titrate too rapidly to 2400 mg/day in adjunctive therapy, as most patients cannot tolerate this dose due to CNS effects 1
• Do not overlook the need for alternative contraception when prescribing to women of childbearing age 4
• Do not forget to monitor and potentially adjust phenytoin doses when using oxcarbazepine at higher doses 4