Anticonvulsants — Mechanisms & Gabapentin

Anticonvulsant Classification
(based on mechanism of action)

• Sodium channel blockers.
  • Examples: phenytoin, carbamazepine, lamotrgine, Na valproate
  • These promote the inactive state of voltage activated Na channels.
  • Increased neuron refractory period to action potential generation.
  • Rapid repetitive firing is diminished, spread of electrical activity to adjacent brain areas is suppressed.
• Drugs that enhance GABA mediated synaptic inhibition.
  • Increases the influx of chloride ions into the cell and hyperpolarizes the neuron.
    3 mechanisms:
    • Act on GABA receptor. Example: benzodiazepines, barbiturates.
    • Inhibit GABA transporter and reduce neuronal GABA reuptake. Example: tiagabine.
    • Promote GABA release. Example: gabapentin.
• Drugs that inhibit pre-synaptic Calcium channels.
  • Example.: Na valproate, ?levetiracetam
  • Limit activation of voltage activated Ca channel known as the T current
• Drugs that inhibit AMPA Kinate.
  • Example.: Topiramate
  • Limit proexcitatory action of glutamate
• Drugs that NT release.
  • Example.: ?levetiracetam
  • Binds to synaptic vesicle glycoprotein SV2A reducing exocytosis of synaptic vesicles