What is the recommended dosage and administration of Oxcarbazepine (Trileptal) for a patient with partial seizures or generalized tonic-clonic seizures?

Oxcarbazepine Dosing for Partial and Generalized Tonic-Clonic Seizures

For adults with partial seizures, start oxcarbazepine at 600 mg/day divided twice daily as adjunctive therapy, increasing by 600 mg/day weekly to a maximum of 1,200 mg/day, though doses up to 2,400 mg/day may be used for monotherapy if tolerated. 1

Adult Dosing Protocols

Adjunctive Therapy

• Initial dose: 600 mg/day divided twice daily 1
• Increase by maximum 600 mg/day at weekly intervals 1
• Target maintenance dose: 1,200 mg/day 1
• Maximum dose: 2,400 mg/day, though most patients cannot tolerate this due to CNS effects 1
• Alternative slower titration (better tolerated): Start 150 mg on day one, then 300 mg daily, increasing by 300 mg weekly 2, 3

Conversion to Monotherapy

• Start oxcarbazepine at 600 mg/day (twice daily) while simultaneously reducing concomitant antiepileptic drugs 1
• Withdraw concomitant AEDs completely over 3-6 weeks 1
• Increase oxcarbazepine by maximum 600 mg/day weekly to reach 2,400 mg/day over 2-4 weeks 1

Initiation of Monotherapy

• Start at 600 mg/day (twice daily) 1
• Increase by 300 mg/day every third day to reach 1,200 mg/day 1
• Maximum effective dose: 2,400 mg/day 1

Pediatric Dosing (Ages 2-16 Years)

Adjunctive Therapy (Ages 4-16)

• Initial dose: 8-10 mg/kg/day (maximum 600 mg/day), divided twice daily 1
• Reach target maintenance dose over 2 weeks based on weight: 1
  • 20-29 kg: 900 mg/day
  • 29.1-39 kg: 1,200 mg/day

  • 39 kg: 1,800 mg/day

• Median dose achieved: 31 mg/kg/day (range 6-51 mg/kg) 1

Adjunctive Therapy (Ages 2-<4)

• Initial dose: 8-10 mg/kg/day (maximum 600 mg/day), divided twice daily 1
• For patients <20 kg, consider starting at 16-20 mg/kg/day 1
• Maximum maintenance: 60 mg/kg/day over 2-4 weeks 1
• Children 2-<4 years may require up to twice the dose per kg compared to adults 1
• Children 4-≤12 years may require 50% higher dose per kg compared to adults 1

Conversion to Monotherapy (Ages 4-16)

• Start at 8-10 mg/kg/day (twice daily) while reducing concomitant AEDs 1
• Withdraw concomitant AEDs over 3-6 weeks 1
• Increase oxcarbazepine by maximum 10 mg/kg/day weekly 1

Initiation of Monotherapy (Ages 4-16)

• Start at 8-10 mg/kg/day (twice daily) 1
• Increase by 5 mg/kg/day every third day 1
• Target doses range from 600-2,100 mg/day depending on weight 1

Critical Monitoring and Safety Considerations

Hyponatremia Surveillance

• Hyponatremia (sodium <125 mmol/L) develops in approximately 2.7-3% of patients 4, 5
• Most cases are asymptomatic and develop gradually during first months of therapy 4
• Monitor serum sodium if: 4
  • Patient has renal disease
  • Taking medications that lower sodium (diuretics, oral contraceptives, NSAIDs)
  • Clinical symptoms of hyponatremia develop
  • Adding medications known to decrease sodium levels
• Routine baseline sodium monitoring is unnecessary unless risk factors present 2, 4

Drug Interactions

• Oxcarbazepine significantly decreases levels of oral contraceptives (ethinylestradiol and levonorgestrel) 2, 5
• Women using hormonal contraception require additional contraceptive precautions 2
• Can increase phenytoin serum concentrations 3, 5
• Minimal cytochrome P450 involvement reduces interaction potential compared to carbamazepine 3, 5

Carbamazepine Switching Protocol

• Overnight switch from carbamazepine to oxcarbazepine (1:1.5 ratio) only recommended for patients on <800 mg/day carbamazepine 2
• For higher carbamazepine doses, use slower switching due to individual variations in carbamazepine enzyme autoinduction 2
• Oxcarbazepine is NOT first-choice alternative for patients with carbamazepine rash due to increased cross-reactivity risk 2

Common Pitfalls to Avoid

• Avoid rapid titration in all patients: The slower 150 mg starting dose with 300 mg weekly increases is better tolerated than the standard 600 mg starting dose 2, 3
• Do not use oxcarbazepine as carbamazepine substitute in rash-sensitive patients: Cross-reactivity occurs in patients who developed carbamazepine rash 2
• Counsel all women of childbearing age about contraceptive failure risk before initiating therapy 2, 5
• Doses above 1,200 mg/day in adjunctive therapy show limited additional benefit and poor tolerability 1
• No routine hematological monitoring required (unlike carbamazepine) as severe blood dyscrasias not reported 2
• No therapeutic drug level monitoring needed 3