Lamotrigine

General

  • Type: Anticonvulsants
  • Dosage Forms: 5mg, 25mg, 50mg, 100mg, 150mg, 200mg
  • Common Trade Names: LaMICtal (ODT, Starter, XR)

Adult Dosing

  • Lennox-Gaustaut: Oral (Immediate release formulation)
    • Non-enzyme inducing AED adjuncts: Week 1-2, 25mg qday, week 3-4, 50mg qday, then increased by 50mg qday every 1-2 weeks; maintenance 225-375mg daily in 2 divided doses
    • Valproate adjunct: Week 1-2, 25mg qod, week 3-4, 25mg qday, then increased by 25-50mg qday every 1-2 weeks; maintenance 100-400mg daily
    • Enzyme inducing AED adjunct: Week 1-2, 50mg qday, week 3-4, 50mg bid, then increased by 100mg qday every 1-2 weeks; maintenance 300-500mg daily in 2 divided doses
  • Partial seizures and primary generalized tonic-clonic seizures
    • Immediate release formulation: same as for Lennox-Gaustaut dosing
    • Extended release formulation:
      • Non-enzyme inducing AED adjuncts: Week 1-2, 25mg qday, week 3-4, 50mg qday, week 5, 100mg qday, week 6, 150mg qday, week 7, 200mg qday, week 8 and beyond, dose increases should not exceed 100mg qday at weekly intervals; maintenance 300-400mg daily
      • Valproate adjunct: Week 1-2, 25mg qod, week 3-4, 25mg qday, week 5, 50mg qday, week 6, 100mg qday, week 7, 150mg qday, week 8 and beyond, does increases should not exceed 100mg qday at weekly intervals; maintenance 200-250mg daily
      • Enzyme inducing AED adjunct: Week 1-2, 50mg qday, week 3-4, 100mg qday, week 5, 200mg qday, week 6, 300g qday, week 7, 400mg qday, week 8 and beyond, dose increases should not exceed 100mg qday at weekly intervals; maintenance 400-600mg daily

Pediatric Dosing

  • Increased risk of developing serious skin rashes
  • Oral
    • Children 2-12 years: Immediate release formulation
    • Non-enzyme inducing AED adjuncts: Week 1-2, 0.3mg/kg/day, week 3-4, 0.6mg/kg/day, then increased by 0.6mg/kg/day every 1-2 weeks; maintenance 4.5-7.5mg/kg/day
    • Valproate adjunct: Week 1-2, 0.15mg/kg/day, week 3-4, 0.3mg/kg/day, then increased by 0.3mg/kg/day every 1-2 weeks; maintenance 1-5mg/kg/day
    • Enzyme inducing AED adjunct: Week 1-2, 0.6mg/kg/day, week 3-4, 1.2mg/kg/day, then increased by 1.2mg/kg/day every 1-2 weeks; maintenance 5-15mg/kg/day
    • Adolescents >12 years: Refer to adult dosing

Special Populations

  • Pregnancy Rating: C
  • Lactation: 50% enters breast milk. Apnea, drowsiness, poor sucking.
  • Renal Dosing: Decreased dosage may be effective; no adequately studied.
  • Hepatic Dosing
    • Mild: no adjustment
    • Mod-severe without ascites: Decrease by 25%
    • Mod-severe with ascites: Decrease by 50%

Contraindications

  • Allergy to class/drug

Adverse Reactions

Serious

  • Serious skin reactions, Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis
  • Suicidal ideation
  • Hypersensitivity reaction

Common

  • Nausea, vomiting, abdominal pain
  • Chest pain, edema
  • Insomnia, somnolence, fatigue, dizziness
  • Rash
  • Dysmenorrhea
  • Rhinitis
  • Blurry vision
  • Panctytopenia

Pharmacology

  • Half-life: 25-33 hours
  • Metabolism: Hepatic and renal
  • Excretion: Urine (94%), feces (2%)
  • Mechanism of Action: Inhibits glutamate release and inhibits voltage-sensitive sodium channels

See Also

References