Lamotrigine is a mood stabilizer used in the treatment of bipolar disorder It is more effective for the treatment/prevention of depression than mania in bipolar disorder.

  • ↓ glutamate release
  • Blocks α subunit of VSNaC
  • May modulate reuptake of 5HT & may block reuptake of DA
  • Dose range: 25-200mg
  • Do a slow titration to reduce risk of SJS
    • e.g. - 25mg x 2 weeks, then 50mg x 2 weeks, etc.

Lamotrigine has significant drug-drug interactions with valproic acid.

  • Medical monitoring:
    • FDA black box 0.8/1000 risk of Stevens Johnson Syndrome (higher risk if concurrent valproate or age <16 [8/1000])
    • Interaction with hormonal contraceptives (estrogen ↑ clearance of lamotrigine; and lamotrigine ↓ level of progestin by ~20%)
  • Toxic Epidermal Necrosis is also a significant risk
  • Using it with VPA also increases the level

Stevens-Johnson Syndrome

Lamotrigine carries a ~1/1000 risk of developing Stevens-Johnson Syndrome. A benign rash occurs in 10% of patients, and is minimized by starting slow and low. The benign rash usually happens in the first 4 weeks. The benign rash is usually maculopapular and not vesicular, and is more frequently seen in kids. While the exact causal relation remains unclear, certain Human Leukocyte Antigen (HLA) types have been associated with the development of SJS/TEN following lamotrigine use, including HLA-B*15:02 in the Han Chinese population.[1]

GI side effects include abdominal pain, indigestion, nausea, vomiting. Other side effects include asthenia, pain, ataxia, dizziness, headache, somnolence, and hypochloremia, double vision, unsteadiness, tremor, sedation. Weight gain less common than with other mood stabilizers