Carbamazepine
Class: Antiepileptic (sodium channel blocker)
Indications
- Partial seizures with or without secondary generalization
- Generalized tonic-clonic seizures
- Trigeminal neuralgia
- Bipolar disorder (mood stabilizer)
Mechanism of Action
- Blocks voltage-gated sodium channels in neurons
- Stabilizes hyperexcited neuronal membranes
- Reduces repetitive firing and spread of seizure activity
Dosage
- Adults (seizures): 200 mg twice daily initially, may titrate to 800–1200 mg/day in divided doses
- Children: 10–20 mg/kg/day in divided doses
- Maximum: Usually 1200 mg/day in adults, adjust based on serum levels
- Available as tablets, chewable tablets, suspension, and extended-release tablets
Major Side Effects
- Dizziness, drowsiness, ataxia
- Diplopia, blurred vision
- Rash, Stevens-Johnson syndrome (rare, especially in HLA-B*1502 carriers)
- Hyponatremia (SIADH)
- Hepatotoxicity (rare)
- Blood dyscrasias: leukopenia, aplastic anemia (rare)
Contraindications
- Hypersensitivity to carbamazepine or tricyclic compounds
- Bone marrow suppression
- History of hypersensitivity to other anticonvulsants (caution)
- Concomitant use of MAO inhibitors (within 14 days)
Compatible Solvent / Administration
- Oral tablets, chewable tablets, suspension
- Extended-release tablets for once or twice daily dosing
Special Precautions
- Monitor liver function, CBC, and serum sodium during therapy
- Test HLA-B*1502 in Asian populations to avoid SJS/TEN
- May reduce efficacy of hormonal contraceptives
- Do not abruptly discontinue; taper gradually
Key Point: Carbamazepine is a widely used antiepileptic and mood stabilizer; careful monitoring is essential due to risk of rash, blood dyscrasias, and hyponatremia.