Class
- Antiepileptic drug (AED)
Carbamazepine
Commonly Prescribed for
(FDA approved in bold)
- Complex partial seizures with or without secondary generalization (adults and children, monotherapy and adjunctive)
- Generalized tonic-clonic seizures
- Mixed seizure patterns
- Trigeminal neuralgia
- Glossopharyngeal neuralgia
- Lennox-Gastaut syndrome
- Temporal lobe epilepsy (children and adults)
- Neuropathic pain
- Alcohol withdrawal
- Restless legs syndrome
- Bipolar I Disorder (acute manic and mixed episodes)
- Psychosis/Schizophrenia (adjunctive)
Carbamazepine
How the Drug Works
- Blocks voltage-dependent sodium channels
- Modulates sodium and calcium channels and GABA and glutamate transmission
Carbamazepine
How Long Until It Works
- Seizures – 2 weeks or less
- Trigeminal neuralgia or neuropathic pain – hours to weeks
- Mania – weeks
Carbamazepine
If It Works
- Seizures – goal is the remission of seizures. Continue as long as effective and well-tolerated. Consider tapering and slowly stopping after 2 years without seizures, depending on the type of epilepsy
- Trigeminal neuralgia – should dramatically reduce or eliminate attacks, pain may recur. Periodically attempt to reduce to lowest effective dose or discontinue
Carbamazepine
If It Doesn’t Work
- Increase to highest tolerated dose. Subject to autoinduction, meaning that dose requirements can change over time
- Epilepsy: consider changing to another agent, adding a second agent or referral for epilepsy surgery evaluation. Check level if compliance is in question. When adding a second agent, keep drug interactions in mind
- Trigeminal neuralgia: Try an alternative agent. For truly refractory patients referral to tertiary headache center, consider surgical or other procedures
Carbamazepine
Best Augmenting Combos for Partial Response or Treatment-Resistance
- Epilepsy: drug interactions can complicate multi-drug therapy
- Pain: Can combine with other AEDs (gabapentin or pregabalin) or tricyclic antidepressants
Carbamazepine
Tests
- Baseline CBC, liver, kidney, and thyroid tests
- Check CBC biweekly for 2 months then every 3 months
- Liver, kidney, and thyroid tests every 6–12 months
- Check sodium levels for symptoms of hyponatremia
Adverse Effects (AEs)
Carbamazepine
How Drug Causes AEs
- CNS AEs are probably caused by sodium channel blockade effects
- Mild anticholinergic side effects
Carbamazepine
Notable AEs
- Sedation, dizziness, ataxia, headache, nystagmus
- Nausea, vomiting, abdominal pain, constipation, pancreatitis, loss of sex drive
- Aching joints and leg cramps
- Elevated liver enzymes
- Benign leukopenia (transient; in up to 10%)
Carbamazepine
Life-Threatening or Dangerous AEs
- Rare blood dyscrasias: aplastic anemia, agranulocytosis
- Dermatologic reactions including toxic epidermal necrolysis and Stevens-Johnson syndrome. (More common in Asian patients.) Can aggravate rash of lupus
- Can reduce thyroid function
- Hyponatremia/SIADH (syndrome of inappropriate antidiuretic hormone secretion)
- May increase seizure frequency in patients with generalized seizure disorders
Carbamazepine
Weight Gain
- Not unusual
Carbamazepine
Sedation
- Problematic
- May limit use
Carbamazepine
What to Do About AEs
- Take with food, split dose, and take higher dose at night to improve tolerability
- Extended-release form may be better tolerated
- Rashes are common but usually not severe. Usually resolves with time or decreased dose. If severe stop drug. Do HLA typing prior to use in Asian patients
- Elevated liver enzymes usually resolve spontaneously
