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Altered phenytoin pharmacokinetics in children with severe, acute traumatic brain injury

C D Stowe1, K R Lee, S A Storgion

  • 1University of Arkansas for Medical Sciences, Little Rock, USA.

Journal of Clinical Pharmacology
|February 24, 2001
PubMed

Insights

Severe traumatic brain injury in children significantly alters phenytoin protein binding and metabolism. Phenytoin metabolism was initially inhibited, then induced to levels twofold higher than in nonstressed children, impacting drug efficacy.

Area of Science:

  • Pharmacokinetics
  • Neuroscience
  • Pediatric Critical Care

Background:

  • Severe acute traumatic brain injury (TBI) can significantly impact drug pharmacokinetics in pediatric patients.
  • Understanding alterations in phenytoin protein binding and metabolism is crucial for optimizing treatment in pediatric TBI.

Purpose of the Study:

  • To investigate the effects of severe acute TBI on phenytoin protein binding and metabolism in prepubescent children.
  • To characterize changes in phenytoin pharmacokinetics within the first 10 days post-injury.

Main Methods:

  • Serial phenytoin serum concentrations were measured in 10 pediatric TBI patients receiving standard dosing.
  • Michaelis-Menten pharmacokinetic models (time-invariant and time-variant) were applied to unbound phenytoin data.
  • Albumin levels were monitored to assess their impact on phenytoin binding.

Main Results:

  • Albumin concentrations decreased significantly over time and predicted phenytoin binding ratios.
  • A time-variant pharmacokinetic model better described phenytoin disposition in most patients.
  • Initial rapid inhibition of phenytoin metabolism was followed by a twofold induction compared to nonstressed children.

Conclusions:

  • Severe acute TBI markedly alters phenytoin protein binding and metabolism in prepubescent children.
  • Dynamic changes in phenytoin metabolism necessitate careful therapeutic drug monitoring in pediatric TBI.
  • These findings highlight the need for individualized phenytoin dosing strategies in pediatric neurotrauma.

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