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Morphine glucuronidation in preterm neonates, infants and children younger than 3 years

Catherijne A J Knibbe1, Elke H J Krekels, Johannes N van den Anker

  • 1Department of Clinical Pharmacy, St Antonius Hospital, 3430 EM Nieuwegein, the Netherlands. c.knibbe@antoniusziekenhuis.nl

Clinical Pharmacokinetics
|August 5, 2009
PubMed

Insights

Pediatric morphine dosing was optimized using pharmacokinetic modeling. A reduced maintenance dose for newborns under 10 days ensures safe and effective morphine concentrations in children.

Area of Science:

  • Pharmacokinetics and Pharmacodynamics
  • Pediatric Drug Dosing
  • Neonatal Pharmacology

Background:

  • Off-label drug use in children necessitates rational dosing strategies.
  • Understanding age-related changes in drug metabolism is crucial for pediatric patients.
  • Morphine and its metabolites were used to study glucuronidation in young children.

Purpose of the Study:

  • To investigate the influence of aging on glucuronidation capacity in newborns and young children.
  • To develop a pharmacokinetic model for morphine in pediatric populations.
  • To establish evidence-based dosing schemes for intravenous morphine in children under three years.

Main Methods:

  • A population pharmacokinetic model was developed using NONMEM V software.
  • Data from 248 infants (500g to 18kg) with 2159 morphine concentrations were analyzed.
  • The model was internally validated using normalized prediction distribution errors.

Main Results:

  • Bodyweight significantly influenced morphine glucuronidation and elimination clearances (allometric scaling factor 1.44).
  • Postnatal age (<10 days) was a key covariate for glucuronidation clearance, independent of other factors.
  • Distribution volumes demonstrated a linear relationship with bodyweight.

Conclusions:

  • Model-based simulations suggest a dosing regimen (loading and maintenance doses) that maintains consistent morphine and metabolite concentrations across the studied age range.
  • A 50% reduction in maintenance dose for newborns under 10 days is recommended.
  • Further pharmacodynamic studies are required to determine target concentrations and finalize dosing recommendations for pediatric populations.
Abstract

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