Anticonvulsants

Categories:

  • Seizures
    • Partial focal, yes or no
    • Simple partial focal no
    • Complex partial focal yes
    • Gen, abs, tonic all ye and yes
    • Absence Seizures
      • Diffuse 3-Hz and wave pattern on EEG
      • Short period of profound impairment with intact body tone
    • Generalized tonic-clonic
      • Abrupt loss of consciousness, stiffening of the muscles, rhythmic jerking of extremities, open eyes during ictus
      • Most fall asleep immediately after seizure and have postictal confusion on awakening
    • Psychogenic nonepileptic seizure (PNES)
      • Conversion disorder, not true seizure
      • Forceful eye closure, side to side body movements, rapid alerting and reorienting, memory recall of seizure
      • NOT associated with abnormal cortical activity, lack post-ictal confusion
      • Intact reflexes, pelvic thrusts
      • Prolactin formal 15-30 minutes after seizure (elevated in epileptic seizure)
      • Video electroencephalogram gold standard, Psychiatric Assessment
        • Lack of epileptiform activity (normal EEG)
  • Barbiturates
    • Phenobarbital
      • MOA: Increases GABAa action
      • SE: Sedation, dependence, Megaloblastic Anemia (Impaired folic acid absorption), Decreases OCP efficacy
    • Pentobarbital
    • Secobarbital
    • Primidone
      • SE: Megaloblastic Anemia (Impaired folic acid absorption)
  • Carbamazepine (Tegretol)
    • MOA: Blocks Na+ channels
    • Anticonvulsant, anticholinergic, antineuralgic, antidiuretic
    • Antiseizure, trigeminal neuralgia, bipolar
    • SE: Decreases T3/T4 (increased deiodination mainly), Decreases OCP efficacy, diplopia, ataxia, blood dyscrasias, liver toxic, SIADH, SJS
  • Ethosuximide (Zarontin)
    • MOA: Blocks thalamic T-type Ca2+ channels
    • USE: Absence seizures only
    • SE: Fatigue, GI distress, Headache, itching, SJS
  • Gabapentinoids
    • Gabapentin (Neurontin)
      • Dose: 100mg TID up to 900mg TID
        • Renally cleared
        • Antacids decrease bioavailability by 20%
      • MOA: Increases GABA and 5HT
      • Use: Add on for seizures only
        • Off-label: sleep, bipolar, migraines, fibromyalgia, anxiety, diabetic and HIV neuropathy
      • SE: somnolence, ataxia, diplopia, dizziness
    • Pregabalin
  • Lacosamide (Vimpat)
  • Lamotrigine (Lamictal)
    • Dose: 12.5mg BID for 2 weeks, 25mg BID for 2 weeks, 50mg BID after
      • Dose doubled w/carbamazepine, phenytoin, phenobarbital
      • Dose every other day with VPA
      • ODT and chewable available
    • MOA: Folate antagonist, voltage gated sodium channel blocker, inhibits 5HT reuptake, inhibits release of glutamate
      • Oral contraceptives decrease Lamictal by 50%
    • Use: Depressive symptoms of bipolar depression (not acute), partial epilepsy, Lennox-Gestalt seizures, Rhett’s, Alzheimer’s aggression
      • 25-hour half-life
    • SE: Benign maculopapular rash(8%) within 4m ≥ SJS/TEN (0.08%)
      • Worse if <16 or with VPA
      • Minimal sedation, minimal weight gain, mild dizziness, nausea
      • Disrupts sleep if taken after 5pm
  • Levetiracetam (Keppra)
    • No close monitoring needed
    • SE: Fatigue, drowsiness, headache
      • Exacerbate depression, anxiety, irritability, non-specific psychiatric adverse effects
      • GAD and nervousness, mc in pre-existing anxiety
  • Oxcarbazepine (Trileptal)
    • Dose: 300mg at night up to 600mg BID, no need for food
    • MOA: Monohydroxy metabolite, voltage gated sodium channel blocker
      • Decreased by ETOH and phenytoin
    • Use: Epilepsy, Intermittent Explosive Disorder
    • SE: sedation, nausea, dizziness, vertigo, hyponatremia (3%), decreases OCP efficacy
  • Phenytoin (Dilantin)
    • SE: Megaloblastic Anemia (Impaired folic acid absorption), Decreases T3/T4 (increased deiodination mainly), Decreases OCP efficacy
    • Fosphenytoin (Cerebyx)
  • Tiagabine
    • MOA: Increases GABA by inhibiting reuptake
    • Use: Only focal seizures
  • Topiramate (Topamax)
    • Dose: 25mg at bedtime up to 25mg BID
    • MOA: Increases cerebral GABA
      • Increases phenytoin and VPA
      • CBZ and phenytoin decrease
      • Avoid with acetazolamide
    • Use: Epilepsy, Migraine Prophylaxis, smoking cessation, tremor, bulimia, binge eating, anxiety, weight loss
      • 24-hour half-life, Renally excreted 70%
    • SE: Decreases OCP efficacy, Mixed RTA by inhibiting carbonic anhydrase in proximal and distal tubules, paresthesia, weight loss, sedation, dizziness, word-finding difficulties (≥100mg), Cognitive suppression and sedation that does not improve with time, reduced delayed recall, slow to complete projects
      • Numbness and tingling in fingertips and peripheral extremities (may be improved by QHS dosing)
      • Lowers serum bicarb, Urine pH ≥6 and hypocitraturia, increased risk for calcium phosphate stones and cardiac arrythmias in 1.5%
  • Valproic Acid (VPA)
  • Vigabatrin
    • MOA: Increases GABA, irreversible GABA transaminase inhibitor
    • SE: Permanent visual loss (Black box)
  • Zonisamide (Zonegran)
  • Anticonvulsant Hypersensitivity Syndrome
    • Occurs after recent seizure
    • Can occur with phenytoin, carbamazepine, phenobarbital, lamotrigine
    • Symptoms
      • Fever, rash, lymphadenopathy
    • Labs
      • Eosinophilia
      • Elevated Transaminases

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