Carbamazepine

General

• Type: Anticonvulsant, antimanic
• Dosage Forms:tablet (chewable, immediate-release, ER), capsule (ER), oral suspension
• Dosage Strengths: chewable tablet: 100mg; immediate-release tablet: 200mg; extended-release tablet: 100, 200, 400mg; extended-release capsule: 100, 200, 300mg; oral suspension: 100mg/5mL; IV solution: 10mg/mL
• Routes of Administration: PO, IV
• Common Trade Names: Tegretol, Equetro, Epitol, Tegretol XR, Carbagen SR, Carbatrol, Teril, Carnexiv

Adult Dosing

Epilepsy

• Maintenance dose:800-1200mg/day PO in divided doses
  
• Therapeutic range: 4-12mg/L (16.9-50.8 micromoles/L)
  
• Max dose: 1600mg/day (rarely 1.6-2.4g/day)
  

Trigeminal Neuralgia

• Maintenance dose: 400-800mg/day PO in divided doses
• Max dose: 1200mg/day
  

Bipolar Mania

• Initial 200mg PO q 12h increase by 200mg/day
  
• Max dose 1600mg/day
  

Restless legs syndrome (off label)

• 100-600mg PO qHS up to 5 weeks
  

Schizophrenia (off label)

• 200-1300mg/day for 2.5-8 weeks
  

Postherpatic Neuralgia (off label)

• 100-200mg PO qDay, may increase slowly to 1200mg/day

Pediatric Dosing

Epilepsy

<6 years old

• Initial: tablet- 10-20mg/kg/d PO q8-12h, suspension-10-20mg/kg/d PO q6h
• Maintenance: may divide frequency into 3-4 times daily not to exceed 35mg/kg/day
  

>6 years old

• Inital: suspension- 50mg PO q6h, tablet- 100mg PO q12h, may increase q week by 100mg/day
• Maintenance: 400-800mg/day PO q6-8h (immediate release), q12h (ER)
  

>12 years old

• Initial: suspension- 10mL (200mg) PO q6h; tablet- 200mg PO q12h, may increase qWeek q12h (ER); q6-8h (other formulations)

Special Populations

• Pregnancy Rating: D
• Lactation: Enters breast milk; not recommended
• Renal Dosing
  • Adult: GFR<10: 75% of dose and monitor
  • Pediatric: same
• Hepatic Dosing
  • Adult: Use caution, drug primarily metabolized in live
  • Pediatric: same

Contraindications

• Allergy to class/drug
• History of bone marrow suppresion
• MAOI use within last 14d
• coadministration with nefazodone, NNRTIs
• Jaundice, hepatitis
• Pregnancy, especially 1st trimester

Adverse Reactions

Serious

• Toxic epidermal necrolysis and Stevens Johnson syndrome especially in Asian populations
• Aplastic anemia and agranulocytosis
• Hyponatremia

Common

Ataxia, Dizziness, Drowsiness, Nausea, Vomiting, Dry mouth

Pharmacology

• Half-life: 25-65 hr (initial dosing), 10-20 hr after autoinduction; 35-40h (extended release)
• Metabolism: hepatic CYP3A4
• Excretion: Urine (72%), Feces (28%)
• Mechanism of Action: stabilizes inactivated state of sodium channels, making neurons less excitable

See Also

• Anticonvulsants
• Seizure levels and reloading
• Carbamazepine toxicity