Generic Name

Trileptal

Mechanism

• Voltage‑gated sodium channel blockade
• Oxcarbazepine is rapidly converted to MHD, which preferentially stabilizes the inactive state of neuronal sodium channels.
• This reduces repetitive firing of action potentials and dampens hyperexcitable neuronal networks.
• Metabolic modulation
• MHD has a relatively short half‑life (~1 h) and low protein binding (<10 %), limiting interactions with other drugs.

Pharmacokinetics

• Absorption
• Rapid and almost complete oral absorption.
• Bioavailability: ~100 % after a single dose; food decreases absorption by ~15 % but does not impact efficacy.
• Distribution
• Low protein binding (~6 %).
• Lipophilic enough to penetrate the CNS readily.
• Metabolism
• Primarily hydrolyzed to the active MHD.
• Minimal CYP-mediated metabolism → fewer drug‑drug interactions.
• Elimination
• Renal excretion of metabolites: 90 % of the dose.
• Half‑life: 10–12 h (MHD).
• Special populations
• Renal impairment → clearance decreased ~40 % (eGFR ≤ 30 mL/min).
• Hepatic impairment → no dose adjustment but caution advised.

Indications

• Partial‑onset seizures (simple, complex, or generalized tonic‑clonic when partial).
• Adjunctive therapy for uncontrolled partial seizures in adults.
• Seizure adjunct in pediatric patients 2 y + with partial‑onset seizures (under FDA‑approved labeling).

Contraindications

• Hypersensitivity to oxcarbazepine or any excipients.
• Severe hepatic impairment (Child‑Pugh B/C).
• Hyponatremia or SIADH—use with caution; monitor serum sodium.
• Pregnancy, lactation, or fertility concerns: Category C; only if benefits outweigh risks.

Dosing

• Can be taken with or without food.
• Titration schedule: If a rash develops, reduce the dose by 50 % and re‑increase slowly.
• For patients switching from carbamazepine, overlap for 1–2 weeks and taper carbamazepine.

Adverse Effects

Common
• Dizziness, vertigo, light‑headedness
• Nausea, vomiting, dyspepsia
• Headache, fatigue, insomnia
• Rash (maculopapular)
• Hyponatremia (especially in elderly or those with SIADH)

Serious
• Stevens–Johnson syndrome / toxic epidermal necrolysis (rare)
• Severe hyponatremia → seizures, coma
• Hepatotoxicity (ALT/AST ↑>3× ULN)
• QT prolongation (rare)
• Congestive heart failure in predisposed patients

Monitoring

• Serum Sodium: Check baseline, 1 week, then monthly for the first 3 months.
• Liver Function Tests (ALT/AST, bilirubin): Baseline, 1 month, then every 3 months.
• Renal Function (CrCl/eGFR): Baseline, then annually or sooner if renal status changes.
• Blood Pressure & Electrocardiogram: Especially in patients with cardiac disease.
• Drug Levels: Generally not needed; but if poor seizure control, consider measuring MHD.

Clinical Pearls

• Titrate Slowly: Oxcarbazepine’s rash occurs early; a 2–4 week titration window helps prevent severe skin reactions.
• Monitor Sodium in At‑Risk Populations: Elderly, patients with heart failure, or those on diuretics—hyponatremia can be life‑threatening.
• Avoid in Severe Hepatic Disease: Metabolite elimination is primarily renal; hepatic injury may be amplified.
• Pregnancy Consideration: Category C; if seizure‑preventive effects outweigh fetal risk, consider close fetal monitoring.
• Drug Interactions: While minimal CYP induction, oxcarbazepine can reduce estrogen‑based oral contraceptive levels → use barrier methods while on therapy.
• Renal Dose Adjustment: In CKD Stage 4/5 (eGFR < 15 mL/min), limit daily dose to 600 mg BID and monitor creatinine closely.
• Quick Onset: Trileptal can achieve therapeutic levels within hours of dose; useful in acute seizure clusters where rapid control is desired.

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• *For further reference, consult the FDA labeling and the latest consensus guidelines from The American Academy of Neurology on antiepileptic drug selection.*