Oxcarbazepine is a carbamazepine derivative with better tolerability and fewer drug interactions.
Also known as: trileptal, oxcarbazepino
DailyMed/FDA — Trileptal; EMC-UK — Oxcarbazepine
DailyMed/FDA — Trileptal; EMC-UK
Antiepileptic + antiepileptic: oxcarbazepine reduces phenytoin levels 20-30%.
MHD (active metabolite of oxcarbazepine) may compete for plasma protein binding and weakly induce CYP, reducing phenytoin levels 20-30%. The effect is more pronounced at higher oxcarbazepine doses (>1200 mg/day). Monitor phenytoin levels (target: 10-20 μg/mL) and signs of toxicity.
Oxcarbazepine (MHD) reduces phenytoin 20-30%. Monitor phenytoin levels.
Oxcarbazepine (MHD) may compete for plasma protein binding and induce CYP, reducing phenytoin levels. The effect is more pronounced at higher oxcarbazepine doses.
Phenytoin levels, signs of toxicity.
Ataxia, nystagmus, toxicity.
Monitor phenytoin levels. Adjust dose as needed.
DailyMed/FDA; EMC-UK
CYP3A4 inducer + CYP3A4 inhibitor: opposing effects — unpredictable outcome.
Oxcarbazepine (MHD) moderately induces CYP3A4, while ritonavir potently inhibits CYP3A4. The outcome depends on dose and timing — generally ritonavir's inhibitory effect predominates. However, oxcarbazepine may compromise pre-exposure prophylaxis (PrEP) or integrase inhibitor-based ARV regimens. Consider switching oxcarbazepine to levetiracetam (does not induce CYP) in HIV patients.
Oxcarbazepine moderately induces CYP3A4. Opposing effect to ritonavir. Unpredictable outcome.
Oxcarbazepine (MHD) moderately induces CYP3A4. Ritonavir potently inhibits CYP3A4. The outcome depends on dose and timing. Generally, ritonavirs inhibitory effect predominates.
ARV levels, signs of therapeutic failure.
ARV therapeutic failure.
Monitor ritonavir and ARV levels. Consider switching oxcarbazepine to levetiracetam (does not induce CYP).
DailyMed/FDA; EMC-UK
CYP inducer + anticoagulant: oxcarbazepine may reduce warfarin effect.
Oxcarbazepine induces CYP3A4 and CYP2C9, metabolic pathways for warfarin (S and R enantiomers). Co-administration may significantly reduce INR, increasing thromboembolic risk. Monitor INR weekly during the first 4 weeks after initiation or dose change.
Oxcarbazepine induces CYP3A4/2C9, reducing warfarin effect. Monitor INR.
Oxcarbazepine induces CYP3A4 and CYP2C9, metabolic pathways for warfarin (S and R enantiomers). Co-administration may significantly reduce INR.
INR, signs of thromboembolism.
Thromboembolism, subtherapeutic INR.
Monitor INR weekly during the first 4 weeks. Adjust warfarin dose as needed.
DailyMed/FDA; EMC-UK
Grapefruit juice inhibits intestinal CYP3A4, potentially slightly increasing oxcarbazepine absorption. Effect generally minimal.
No significant restriction. Take with or without grapefruit juice.
No documented disease interactions.
Animal studies show developmental effects. Limited human data.
Insufficient data. Use minimum effective dose.
Excreted in breast milk. May cause neonatal somnolence.
Effects on fertility unknown.
DailyMed/FDA — Trileptal; EMC-UK
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Antiepileptic activity via Na⁺ channel blockade. Prodrug metabolised to MHD.
Prodrug: metabolised to MHD (10-monohydroxyderivative), which blocks voltage-gated Na⁺ channels, stabilising channels in the inactive state. Acts synergistically with phenytoin and valproate.
Rapid and complete oral absorption. Bioavailability: >95%. MHD peak: 4-6 h.
Metabolised by CYP3A4 to MHD. MHD is glucuronidated (UGT). Induces CYP3A4 and UGT (less than carbamazepine — does not form epoxide).
MHD: 9-11 h.
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
