Trileptal (Oxcarbazepine): An Antiepileptic Medication
Trileptal (oxcarbazepine) is an antiepileptic medication primarily used for the treatment of partial-onset seizures in adults and children, with a more favorable side effect and drug interaction profile compared to carbamazepine. 1
Indications and Mechanism of Action
Oxcarbazepine is FDA-approved for:
- Monotherapy in adults with partial-onset seizures
- Monotherapy in children aged 4 years and above with partial-onset seizures
- Adjunctive therapy in children aged 2 years and above with partial-onset seizures 1
The medication works primarily by blocking neuronal sodium channels, which helps stabilize hyperexcited neural membranes and inhibit repetitive neuronal firing that leads to seizures 2, 3.
Chemical Structure and Properties
Oxcarbazepine is structurally related to carbamazepine but has important differences:
- Chemical name: 10,11-Dihydro-10-oxo-5H-dibenz[b,f]azepine-5-carboxamide
- It undergoes different metabolism than carbamazepine, with the primary active metabolite being 10-monohydroxy derivative (MHD)
- Available as 150 mg, 300 mg, and 600 mg film-coated tablets 1
Dosing and Administration
- Initial dosing:
- Adults: Typically 600 mg/day divided into two doses
- Children: 8-10 mg/kg/day in two divided doses 4
- Titration: Can be increased by 150-600 mg/day at 2-7 day intervals depending on clinical response and tolerability
- Maximum recommended dose: 2400 mg/day in adults 5
- Should be taken with food to improve tolerability 4
Efficacy
Oxcarbazepine has demonstrated efficacy in:
- Monotherapy for newly diagnosed partial seizures, with efficacy comparable to phenytoin and valproic acid 5
- Adjunctive therapy for refractory partial seizures, with significant reductions in seizure frequency compared to placebo 3, 6
- Studies show 43-71% of pediatric patients with partial onset seizures become seizure-free with oxcarbazepine monotherapy 3
Advantages Over Other Antiepileptic Drugs
Oxcarbazepine offers several advantages compared to older antiepileptic medications:
- Better tolerability profile than phenytoin and carbamazepine 3, 6
- Lower potential for drug interactions than carbamazepine and other older antiepileptic drugs 5
- Does not require slow titration, allowing for better patient compliance 2
- Metabolism largely unaffected by cytochrome P450 enzyme induction 3
Common Side Effects
- Most common: somnolence, dizziness, headache, nausea, vomiting, and diplopia 5
- Hyponatremia occurs in approximately 3% of patients, usually developing gradually during the first months of therapy 4
- Skin reactions are less common than with carbamazepine 5
Drug Interactions
- Can inhibit CYP2C19 and induce CYP3A4/5, affecting metabolism of certain drugs
- Decreases plasma levels of oral contraceptives, necessitating alternative contraceptive methods
- May increase phenytoin levels when used concomitantly 3, 6
Special Populations
Children
- Effective and generally well-tolerated in children with partial seizures
- Dosing is weight-based (8-10 mg/kg/day initially) 4
Women of Childbearing Age
- Decreases effectiveness of hormonal contraceptives
- Alternative contraceptive methods should be used 3
Monitoring
- Baseline serum sodium not routinely needed unless patient has risk factors for hyponatremia
- Consider monitoring serum sodium if symptoms of hyponatremia develop or if medications known to decrease sodium levels are added 4
- No routine monitoring of liver function, renal function, or hematological parameters is required 4
Oxcarbazepine represents a valuable option for treating partial seizures with a favorable safety profile and reduced potential for drug interactions compared to older antiepileptic medications.