Carbamazepine

Carbamazepine

Indications

• Mania
  • Level I evidence, but (C) due to s/e, drug interactions
• Bipolar depression
  • Level II evidence (C)
• Prophylaxis
  • Level II evidence (C)

Pharmacology

• Half-life is ultimately 5-26 hours
  • Metabolized by the liver
  • Protein bound
• Carbamazepine induces the CYP 450 enzyme system, resulting in:
  • Decreased neuroleptic level
  • Decreased benzodiazepines
  • Decreased TCA
  • Decreased anti-convulsants
  • Auto-induction

Side Effects

• Diplopia
• Blurred vision
• Fatigue, drowsiness
• Ataxia, dizziness
• Nausea, vomiting
• Less common
  • Rashes
  • Decreased WBC
  • Decreased platelets
  • Increased LFTs
  • Hyponatremia

Adverse Reactions

• Idiosyncratic, rare:
  • Agranulocytosis
  • Aplastic anemia
  • Hepatic failure
  • Exfoliative dermatitis (Stevens-Johnson Syndrome)
  • Pancreatitis
• Toxicity symptoms:
  • Dizziness
  • Ataxia
  • Sedation
  • Diplopia
  • Stupor, coma, decreased LOC, convulsions

Starting

• Workup before starting
  • History and Physical
  • CBC with diff, platelets
  • LFT’s
• Start at 100 mg BID
• Increase by 200 mg q5d with levels
  • 800-1000 mg/day
  • Range: 200-1800 mg

Follow up

• Therapeutic levels not established
• We use same as for seizure
• 17-42 μmol/L
• Labwork
  • CBC, platelets q2weeks for first 2 months
  • LFT’s
  • Then q3months along with carbamazepine levels