Generic Name

Oxcarbazepine

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Classification

FDA Approved Indications

• Partial seizures in adults and children over 2 years old
• Secondary generalized seizures

Mechanism of Action

Blocks voltage-sensitive sodium channels, stabilizing hyperexcited neural membranes and reducing repetitive neuronal firing.

Dosage and Administration

Adult: Initial dose typically 300 mg twice daily, titrated up based on response and tolerability.

Pediatric: Dosing individualized based on weight and response; usual starting dose is 8-10 mg/kg/day in divided doses.

Geriatric: Start at lower doses due to increased sensitivity and comorbidities; titrate carefully.

Renal Impairment: Reduce dose in patients with renal impairment; specific adjustments depend on creatinine clearance.

Hepatic Impairment: No specific dose adjustment necessary, but caution advised.

Pharmacokinetics

Absorption: Well absorbed orally.

Distribution: Widely distributed; protein binding approximately 40-45%.

Metabolism: Primarily metabolized to monohydroxy derivative (MHD), which is pharmacologically active.

Excretion: Renal excretion of unchanged drug and metabolites.

Half Life: Approximately 9 hours in adults.

Contraindications

• Hypersensitivity to oxcarbazepine or other carbamazepine-derivatives.

Precautions

• History of hypersensitivity reactions, including Stevens-Johnson syndrome or toxic epidermal necrolysis; monitor for signs of skin reactions.
• Use cautiously in patients with renal impairment, history of hyponatremia, or liver dysfunction.
• Assess for suicidal thoughts or behaviors.

Adverse Reactions - Common

• Dizziness (Common)
• Somnolence (Common)
• Headache (Common)
• Nausea (Common)
• Fatigue (Common)

Adverse Reactions - Serious

• Stevens-Johnson syndrome / Toxic epidermal necrolysis (Rare)
• Hypersensitivity reactions, including hypersensitivity syndrome (Rare)
• Hyponatremia (Less common but significant in susceptible individuals)

Drug-Drug Interactions

• Other CNS depressants, including alcohol
• Hormonal contraceptives (may decrease effectiveness)
• Other medications affecting sodium levels

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Take medication exactly as prescribed.
• Report signs of rash, fever, or hypersensitivity immediately.
• Be aware of potential drowsiness and avoid driving until tolerated.
• Maintain hydration and report symptoms of hyponatremia such as nausea, headache, confusion.

Special Considerations

Black Box Warnings:

• Serious skin reactions (Steven-Johnson syndrome, toxic epidermal necrolysis) especially in certain HLA-B*1502 positive populations—consider genetic testing.
• Potential for suicidal ideation and behavior.

Genetic Factors: HLA-B*1502 genotype testing recommended in at-risk populations (e.g., Han Chinese, Thai).

Lab Test Interference: Can alter sodium and other electrolyte levels.

Overdose Management

Signs/Symptoms: Dizziness, drowsiness, ataxia, coma, seizures.

Treatment: Supportive care; IV fluids; gastric lavage; activated charcoal if recent ingestion; no specific antidote. Dialysis may be considered in severe cases.

Storage and Handling

Storage: Store at room temperature, 20-25°C (68-77°F).

Stability: Stable under recommended storage conditions for the duration specified by manufacturer.