What is Tegretol (carbamazepine) used for and what are its dosing and side effects?

Tegretol (Carbamazepine): Uses, Dosing, and Side Effects

Tegretol (carbamazepine) is primarily used as an anticonvulsant for seizure disorders, for trigeminal neuralgia pain management, and as a mood stabilizer, with dosing typically starting at 100-200 mg twice daily and gradually increasing based on response and tolerability. 1

Primary Indications

Carbamazepine is FDA-approved and clinically used for:

• Seizure disorders:

  • Partial seizures
  • Generalized tonic-clonic seizures
  • Mixed seizure types

• Neuropathic pain:

  • Trigeminal neuralgia
  • Glossopharyngeal neuralgia

• Psychiatric conditions:

  • Bipolar disorder (mood stabilization)

Dosing Guidelines

Initial Dosing

• Adults: Start with 100-200 mg twice daily
• Children: 1 mg/kg initially, gradually titrated to appropriate dosage 2
• For Paroxysmal Kinesigenic Dyskinesia (PKD): Initial dose of 50 mg, adjusted according to effect 2

Maintenance Dosing

• Seizure disorders: 800-1200 mg/day in divided doses
• Trigeminal neuralgia: 400-800 mg/day in divided doses
• PKD treatment: 50-200 mg/day (low-dose effective in 85% of patients) 2

Administration Considerations

• Always take with food to minimize gastrointestinal side effects
• Divide total daily dose into at least two administrations due to short half-life
• Take at bedtime if experiencing daytime drowsiness 2
• Do not stop suddenly - must taper gradually to avoid withdrawal seizures 1

Side Effects

Common Side Effects (30-50% of patients)

• Drowsiness/fatigue
• Dizziness/vertigo
• Unsteadiness/ataxia
• Nausea/vomiting
• Double vision (diplopia)
• Headache 3

Serious Side Effects

1. Dermatologic reactions:

   • Severe skin rashes (including Stevens-Johnson syndrome)
   • Higher risk in patients of Asian descent with HLA-B*15:02 gene 2, 1

2. Hematologic abnormalities:

   • Leukopenia (may be transient or persistent)
   • Aplastic anemia (rare but potentially fatal)
   • Thrombocytopenia 1, 4

3. Hepatic effects:

   • Elevated liver enzymes
   • Rare cases of hepatic failure
   • Vanishing bile duct syndrome 1

4. Cardiac effects:

   • Irregular heartbeat
   • AV heart block (second and third-degree) 1

5. Neurological toxicity:

   • Focal neurological deficits
   • Confusion
   • In severe cases: coma 5

6. Psychiatric effects:

   • Suicidal thoughts or behaviors (rare)
   • Mood changes 1

Monitoring Requirements

Before Starting Therapy

• Complete blood count with platelets
• Liver function tests
• HLA-B*15:02 genetic testing (especially in patients of Asian descent) 2, 1

During Therapy

• Regular monitoring of complete blood counts
• Liver enzyme levels
• Carbamazepine blood levels (therapeutic range: 4-12 μg/mL)
• Clinical monitoring for side effects 4

Important Drug Interactions

Carbamazepine is both affected by other medications and affects the metabolism of many drugs due to its potent induction of CYP3A4 enzyme system 6:

Drugs that increase carbamazepine levels

• Macrolide antibiotics
• Isoniazid
• Verapamil, diltiazem
• Certain antidepressants

Drugs that decrease carbamazepine levels

• Phenytoin
• Phenobarbital
• Primidone

Drugs affected by carbamazepine

• Oral contraceptives (reduced effectiveness)
• Warfarin (reduced anticoagulant effect)
• Other anticonvulsants (valproic acid, lamotrigine)
• Tricyclic antidepressants
• Cyclosporine 6

Special Populations

Pregnancy

• May increase risk of adverse fetal outcomes
• Requires comprehensive risk-benefit evaluation
• Consider discontinuation for mild conditions
• Register with North American Antiepileptic Drug Pregnancy Registry if used during pregnancy 2, 1

Breastfeeding

• Carbamazepine passes into breast milk
• Discuss risks/benefits with healthcare provider 1

Key Warnings

• Never stop taking suddenly - can cause serious withdrawal seizures
• Monitor for early signs of serious reactions: fever, sore throat, rash, bruising, jaundice
• Avoid alcohol which may increase sedative effects
• Use caution with driving or operating machinery due to potential drowsiness and dizziness 1

By following appropriate dosing guidelines and monitoring protocols, carbamazepine can be an effective medication for its approved indications while minimizing the risk of adverse effects.