Epilepsy Meds

• What medications are available for Epilepsy

  • Sodium channel blockers: carbamazepine, oxcarbazepine, lamotrigine (lamictal), phenytoin (dilantin), fosphenytoin, topiramate (topamax)
  • GABA inhibitory transmission: Phenobarbital, Benzodiazepine, Valproic acid
  • Miscellaneous: gabapentin (neurontin), pregabalin (lyrica), levetiracetam (keppra)
• Sodium channel blocker overall MOA

  Bind to and stabilize inactivated Na channels, target channels that open/close more frequently, act specifically on rapidly firing neurons and have less effect on neurons firing fewer action potentials
• Cabamazepine info

  • MOA: enhances Na channel inactivation
  • AE: dizziness, diplopia, leukopenia, hyponatremia
  • PtC: may worsen absence seizure, may not be tolerated as well in elderly
• Oxcarbazepine

  • MOA: enhances Na channel inactivation, modulates calcium channel
  • AE: dizziness, diplopia, ataxia, hyponatremia (worse than carbamazepine), visual disturbances, n/v
  • Monitoring: sodium levels
  • PtC: may reduce effectiveness of contraceptives at doses > 1200 mg/day
• Lamotrigine

  aka Lamictal

  • MOA: enhances Na channel inactivation, decreases glutamate release
  • AE: sedation, diplopia, ataxia, rash (can progress to SJS, pt should report immediately)
  • PtC: taper slowly, other drugs affect half-life, good for pregnancy!!
• Phenytoin and Fosphenytoin

  aka Dilantin

  • MOA: enhances Na channel inactivation
  • AE: nystagmus, ataxia, gingival hyperplasia, osteomalacia
  • PtC: small changes in doses can lead to large increases in plasma concentration
  • Fosphenytoin: prodrug of phenytoin, can be administered IV or IM
• Topiramate

  aka Topamax

  • MOA: enhances Na channel inactivation, acts as an agonist at GABA-A receptors, acts as a glutamate antagonist
  • AE: difficulty concentrating, word finding difficulties, kidney stones, weight loss
  • PtC: Recommend adequate hydration, can decrease contraceptive efficacy with doses >200 mg/day, non-epilepsy uses
• Enhancers of GABA inhibitory transmission overall MOA

  Stimulate release or synthesis of GABA, inhibit GABA transporters so its action is prolonged, inhibit GABA metabolism, enhance effect of GABA on its receptor
• Phenobarbital

  • MOA: promotes the binding of GABA to GABA-alpha receptor and increasing the amount of time the chloride channel is open
  • AE: sedation, paradoxical hyperactivity in children, osteomalacia
  • PtC: not used as readily as other agents bc there’s better options available
• Benzodiazepines

  • MOA: Bind to GABA inhibitory receptors and potentiate the effects of GABA
  • AE: somnolence, dizziness, unsteadiness
  • PtC: non-epilepsy uses, often used as adjunctive therapy, caution in elderly d/t risk of cognitive impairment, delirium, falls, fractures, and motor vehicles accidents in older adults
• Valproic Acid

  • MOA: increases brain concentrations of GABA, possible sodium channel effect, blocks calcium channels involved in neuronal firing
  • AE: sedation, weight gain, hair loss, n/v, thrombocytopenia
  • CI: pregnancy (category x)
  • PtC: also has many non-epilepsy uses
• Gabapentin and Pregabalin

  aka Neurontin and Lyrica

  • MOA: GABA analog that does NOT act at GABA receptors, mechanism unknown, may reduce calcium dependent release of neurotransmitters
  • AE: 
  • Gabapentin: fatigue, ataxia, dizziness
  • Pregabalin: drowsiness, blurred vision, weight gain
  • CI: space gabapentin from antacids
  • PtC: renal dosage adjustments needed, not as efficacious for tx of seizures, many non-epilepsy uses
• Levetiracetam

  aka Keppra

  • MOA: decrease inhibition of GABA channels, block calcium channel, binds with high affinity to synaptic vesicle protein (SV2A)
  • AE: somnolence, dizziness, headache, behavioral changes
  • PtC: assess pt’s mood, dosage adjustment in renal dysfunction, less potential for drug interactions