Lamotrigine

Summary

Lamotrigine is a drug used to treat seizures and bipolar disorder. It works by blocking voltage-gated Na+ channels in the brain, preventing the generation and propagation of action potentials responsible for seizures. Since lamotrigine is a broad spectrum antiepileptic, it can be used to treat a variety of seizures, including focal, tonic-clonic, and absence seizures. Lamotrigine can also be used to treat bipolar disorder and is particularly effective for stabilizing the depressed phase of bipolar disorder. Two rare, but important, side effects of lamotrigine use include a severe rash in Steven Johnsons Syndrome as well as Hemophagocytic Lymphohistiocytosis.

Key Points

• Lamotrigine
  • Mechanism
    • Block voltage-gated Na+ channels
      • Because Na+ channels are used for most neural APs, this essentially explains broad-spectrum antiepileptic effects
    • Inhibits the release of glutamine
  • Clinical Use
    • Broad-spectrum antiepileptic
      • Treats partial (focal) seizures, tonic-clonic seizures, absence seizures
    • Also used in bipolar disorder
      • Particularly useful for treating depressed phase
  • Adverse Effects
    • Steven Johnson Syndrome (SJS)
      • Drug-induced skin and mucosal reaction that may lead to necrosis and peeling
      • Dose-limiting and relatively common; dose must be titrated slowly
    • Hemophagocytic lymphohistiocytosis
      • Black-box warning
      • Characterized by macrophages and lymphocytes destroying RBCs and RBC precursors in the bone marrow, causing severe anemia