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Antiepileptic — Sodium Channel Blocker Pregnancy: Avoid — teratogenic risk; MHRA Valproate-like programme not implemented but folate supplementation essential. Use reliable contraception.

Oxcarbazepine

Brand names: Trileptal

Adult dose

Dose: 300 mg twice daily initially; usual maintenance 600–1200 mg twice daily
Route: Oral
Frequency: Twice daily
Max: 2400 mg/day
Structural analogue of carbamazepine — fewer drug interactions (not CYP3A4 inducer to same degree) and better tolerated. Licensed for focal seizures with or without secondary generalisation. Also used for trigeminal neuralgia. Monitor sodium — hyponatraemia is the key side effect.

Paediatric dose

Dose: 8–10 mg/day/kg
Route: Oral
Frequency: Twice daily
Max: 46 mg/kg/day
Children ≥6 years: start 8–10 mg/kg/day in 2 divided doses. Maximum 46 mg/kg/day.

Dose adjustments

Renal

Reduce starting dose by 50% if eGFR <30 mL/min — active metabolite (MHD) renally excreted.

Hepatic

No adjustment in mild–moderate impairment. Avoid in severe hepatic impairment.

Paediatric weight-based calculator

Children ≥6 years: start 8–10 mg/kg/day in 2 divided doses. Maximum 46 mg/kg/day.

Clinical pearls

  • MHRA: test for HLA-B*1502 allele before starting in patients of Han Chinese or Thai origin — high risk of SJS/TEN
  • Hyponatraemia is the cardinal monitoring parameter — occurs in up to 25% of patients; clinically significant (<125 mmol/L) in ~3%
  • Advantage over carbamazepine: fewer drug interactions and less enzyme induction — preferred when complex polypharmacy present

Contraindications

  • AV block
  • Hypersensitivity to oxcarbazepine or carbamazepine (25–30% cross-reactivity)

Side effects

  • Hyponatraemia (clinically significant — check Na regularly)
  • Dizziness and diplopia
  • Nausea
  • Rash (SJS/TEN risk — HLA-B*1502 in Han Chinese/Thai populations)
  • Sedation
  • Hyponatraemia more common than with carbamazepine

Interactions

  • Combined oral contraceptives (CYP induction — contraception failure; use additional method)
  • Phenytoin (increases phenytoin levels)
  • Carbamazepine (additive CNS effects)
  • Lithium (additive hyponatraemia risk)

Monitoring

  • Serum sodium at baseline and 3 months then 6-monthly
  • LFTs at baseline
  • FBC
  • AED levels not routinely measured (MHD level available if needed)

Reference: BNFc; BNF 90; NICE NG217 (Epilepsies in children and adults); MHRA Oxcarbazepine Safety Update; BNFc. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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