Anticonvulsant Overdoses: Phenytoin, Carbamazepine, Lamotrigine, Topiramate and Gabapentin

First Things First (assess & treat for the following)

Phenytoin

  • Airway management
  • ABCs of resuscitation
  • Toxicity can be caused by propylene glycol as a diluent in IV formulation, or by phenytoin itself.
  • Propylene glycol causes myocardial depression and cardiac arrest.
  • Mild to moderate phenytoin intoxication
    • Nystagmus
    • Ataxia
    • Dysarthria
    • Nausea/vomiting
    • Diplopia
    • Hyperglycemia
    • Agitation
  • Severe phenytoin intoxication
    • Stupor/coma
    • Respiratory arrest
    • Seizures have been reported; however, this should prompt the investigation into other causes.

Carbamazepine

  • Airway management
  • ABCs of resuscitation
  • Toxicity effects from:
    • CNS depression
    • Anticholinergic effects
    • Cerebellar-vestibular brainstem function
  • Mild to moderate overdose
    • Ataxia
    • Nystagmus
    • Ophthalmoplegia
    • Dyskinesia
    • Mydriasis
    • Sinus tachycardia
  • Severe overdose
    • Myoclonus
    • Seizures
    • Hyperthermia
    • Coma
    • Respiratory arrest
    • Atrioventricular block
    • QRS widening
    • QT prolongation

Lamotrigine

  • Airway management
  • ABCs of resuscitation
  • Clinical manifestations of overdose
    • Lethargy
    • Dizziness
    • Ataxia
    • Stupor
    • Nystagmus
    • Hypertonia
    • Seizures
    • QRS prolongation
    • Nausea/vomiting
    • Hypokalemia

Topiramate

  • Airway management
  • ABCs of resuscitation
  • Manifestations of overdose:
    • CNS depression
    • Confusion
    • Slurred speech
    • Ataxia
    • Weakness
    • Tremor
    • Clonus
    • Seizures

Gabapentin

  • Airway management
  • ABCs of resuscitation
  • Manifestations of overdose
    • CNS depression
    • Dizziness
    • Ataxia
    • Tremor
    • Slurred speech
    • Diplopia
    • Tachycardia
    • Hypotension or hypertension
    • Diarrhea

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Last updated: April 17, 2010