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Phenytoin toxicity in two-month-old Thai infant with CYP2C9 gene polymorphism--A case report

Montida Veeravigrom1, Vorapol Jaroonvanichkul2, Wiracha Netbaramee1

  • 1Division of Neurology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Thailand; Division of Neurology, Department of Pediatrics, King Chulalongkorn Memorial Hospital/Thai Red Cross Society, Thailand.

Brain & Development
|May 23, 2015
PubMed

Insights

Phenytoin is an effective antiepileptic drug, but maintaining therapeutic levels in infants is challenging. A two-month-old infant experienced phenytoin toxicity due to a CYP2C9 gene variation, highlighting genetic factors in drug metabolism.

Area of Science:

  • Pharmacogenetics
  • Clinical Pharmacology
  • Pediatric Neurology

Background:

  • Phenytoin is a widely used antiepileptic drug for focal seizures.
  • Maintaining therapeutic phenytoin levels in infants under three months presents clinical challenges.
  • Phenytoin metabolism is significantly influenced by cytochrome P450 enzymes, particularly CYP2C9 and CYP2C19.

Observation:

  • A two-month-old Thai infant presented with symptoms of phenytoin toxicity.
  • This infant had difficulty maintaining therapeutic phenytoin levels.
  • The patient's clinical presentation was unusual given the rarity of phenytoin toxicity in infants.

Findings:

  • The infant exhibited phenytoin toxicity despite standard dosing.
  • Genetic analysis revealed a CYP2C9 gene polymorphism in the infant.
  • This polymorphism likely impaired phenytoin metabolism, leading to toxicity.

Implications:

  • CYP2C9 gene polymorphism can predispose young infants to phenytoin toxicity.
  • Pharmacogenetic profiling may be crucial for optimizing phenytoin therapy in infants.
  • Understanding genetic variations is essential for safe and effective antiepileptic drug use in pediatric populations.

Keywords:
CYP2C9 gene polymorphismInfantPhenytoin toxicity

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