Pharmacology · Antiseizure medicines
Oxcarbazepine !
A relative of carbamazepine for focal seizures. Its active metabolite blocks sodium channels; low blood sodium is its typical problem.
Updated 2026-11-01
The figure shows carbamazepine, a close relative that occupies the same site, bound to human Nav1.7 (SCN9A); no structure with oxcarbazepine or its metabolite is available.
Mechanism of action
Oxcarbazepine is quickly reduced to its 10-monohydroxy metabolite (MHD), which does most of the work. Both block voltage-gated sodium channels, stabilizing hyperexcited membranes, inhibiting repetitive firing and reducing the spread of synaptic impulses.
- Reduced to the active metabolite MHD
- MHD blocks voltage-gated sodium channels
- Repetitive neuronal firing is inhibited
- Focal seizures do not spread
Pharmacokinetics
- Absorption
- Absorbed by mouth
- Metabolism
- Rapidly reduced in the liver to the active metabolite MHD; strong CYP3A4 or UGT inducers lower its levels
- Elimination
- Mainly kidneys; MHD half-life lengthens in severe kidney disease
- Half-life
- About 2 hours for oxcarbazepine and about 9 hours for MHD
Indications
- Focal (partial-onset) seizures, alone or as add-on Epilepsy and seizures →
Adverse effects
Common
- Dizziness and sleepiness
- Double vision and abnormal vision
- Nausea and vomiting
- Unsteadiness, tremor and abnormal gait
- Fatigue and headache
Contraindications
- Hypersensitivity to oxcarbazepine or to eslicarbazepine acetate
Key interactions
- Hormonal contraceptives
- Less contraceptive effect
- Strong CYP3A4 or UGT inducers (carbamazepine, phenytoin, phenobarbital)
- Lower MHD levels
- Other drugs that lower sodium, such as those causing inappropriate ADH secretion
- More hyponatraemia
What is monitored
- Serum sodium, especially in the first months and with other sodium-lowering drugs
- HLA-B*1502 in people with ancestry from at-risk Asian populations
- Skin and signs of hypersensitivity
- Mood and suicidal thoughts
Administration and safety
- Given by mouth as tablets or suspension
- Immediate- and extended-release forms are not interchangeable without care
- Withdrawn gradually: stopping suddenly can trigger seizures
Nursing care
- Ask about previous reactions to carbamazepine
- Watch for headache, confusion, nausea or more seizures that may signal low sodium
- Teach to report rash or fever
- Remind that hormonal contraception may fail
Pregnancy and breastfeeding
MHD levels may fall gradually during pregnancy and recover after delivery, so seizure control is followed closely.
Test yourself
Think of the answer, then tap the question to see it.
What is the active form of oxcarbazepine?
Its 10-monohydroxy metabolite (MHD), which blocks voltage-gated sodium channels and has a longer half-life than the parent drug.
Which electrolyte must be checked during oxcarbazepine treatment?
Sodium: clinically significant hyponatraemia can develop.
Can a patient who had a hypersensitivity reaction to carbamazepine safely switch to oxcarbazepine?
Not without caution: cross-hypersensitivity occurs, and oxcarbazepine is stopped at once if signs appear.
Related drugs
Related conditions
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Oxcarbazepine: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2024); DailyMed - OXCARBAZEPINE tablet, film coated (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.