Oxcarbazepine (Trileptal, Oxtellar XR)
Anticonvulsant • Last reviewed 2025-09-26
General information
Oxcarbazepine (Trileptal; extended-release Oxtellar XR) is a sodium-channel modulating anticonvulsant used off-label as a mood stabilizer for bipolar disorder when carbamazepine is not tolerated. Compared with carbamazepine it has fewer CYP interactions and lower risk of serious rash, but higher rates of hyponatremia.
Formulations include immediate-release tablets/oral suspension and extended-release tablets. Because of auto-induction it reaches steady state within 2–3 days; monitoring sodium is critical, particularly in older adults or those on diuretics.
Common adverse effects: dizziness, somnolence, diplopia, nausea, hyponatremia. Severe rash is rare but possible; cross-reactivity in patients with carbamazepine hypersensitivity occurs in ~25–30%.
Because of the risk of hyponatremia, periodic sodium monitoring is recommended, particularly in older adults, those on SSRIs or diuretics, and during the first 3 months of therapy.
Dosing & administration
Bipolar disorder (off-label): start 300 mg twice daily; increase by 300 mg/day every 3–4 days to 900–1200 mg/day divided.
Extended-release: initiate 600 mg once daily; increase by 600 mg weekly to 1200–2400 mg once daily.
Renal impairment (CrCl <30 mL/min): start 150 mg twice daily and titrate slowly.
Taper gradually to avoid seizure risk when discontinuing.
Dose adjustments
- Moderate renal impairment
- Reduce initial dose by 50%
- Hyponatremia
- Hold or reduce dose; monitor sodium
Mechanism of action
Blocks voltage-sensitive sodium channels, stabilizing hyperexcitable neuronal membranes and reducing repetitive firing.
Metabolized to active monohydroxy derivative (MHD) which accounts for the majority of pharmacologic activity.
Metabolism & pharmacokinetics
Bioavailability ~95%; peak concentrations in 4–6 h (IR) and 7 h (XR).
Extensively metabolized via cytosolic enzymes (non-CYP) to MHD; half-life of MHD ~9 h.
Renal excretion of metabolites; mild inducer of CYP3A4 and inhibitor of CYP2C19.
- Tmax (IR)
- 4–6 h
- Half-life (MHD)
- ~9 h
- Metabolism
- Non-CYP to active MHD
Drug interactions
Induces CYP3A4 and UGT enzymes, reducing efficacy of oral contraceptives.
Inhibits CYP2C19, increasing phenytoin concentrations.
Hyponatremia risk increases with SSRIs, diuretics, and carbamazepine; monitor sodium.
Alcohol and CNS depressants enhance sedation.
| Mechanism | Agents / factors | Management |
|---|---|---|
| CYP3A4 induction | Hormonal contraceptives | Use alternative contraception |
| CYP2C19 inhibition | Phenytoin | Monitor levels and reduce dose |
| Hyponatremia risk | SSRIs, diuretics | Check sodium at baseline and periodically |
Monitoring & safety checks
Serum sodium
Baseline, after dose increases, then periodically • Hyponatremia risk
CBC/LFTs
Baseline and as indicated • Rare hematologic/hepatic effects
Dermatologic assessment
During first 8 weeks • Severe rash monitoring
Warn patients about symptoms of hyponatremia (fatigue, confusion, seizures).
Consider HLA-B*1502 screening in at-risk ancestry if history of carbamazepine reaction.
Discontinuation guidance
Taper by 300 mg/day every week to avoid rebound seizures or mood destabilization.
Adverse effects
Common: dizziness, somnolence, diplopia, nausea, hyponatremia.
Serious: SJS/TEN (rare), anaphylaxis, hematologic reactions.
References
- TRILEPTAL (oxcarbazepine) prescribing information — DailyMed (2024)
- Oxtellar XR prescribing information — DailyMed (2024)
- Oxcarbazepine hyponatremia review — Epilepsy & Behavior (2015) DOI: 10.1016/j.yebeh.2015.05.032
Educational use only — verify details in current prescribing information and authoritative clinical guidelines before making prescribing decisions.