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  • Poster presentation
  • Open Access

Tramadol and O-demethyltramadol disposition in humans: a pooled study

  • 1,
  • 2,
  • 3,
  • 3,
  • 4,
  • 5,
  • 6 and
  • 3
Critical Care201115 (Suppl 1) :P347

  • Published:


  • Tramadol
  • Poor Metabolizer
  • Pool Study
  • Slow Metabolizers
  • Metabolizer Group


To study the use of size, maturation and CYP2D6 genotype score as predictors of i.v. tramadol (M) disposition throughout human life, published observations were pooled [16].


M and O-demethyltramadol (M1) observations in 295 subjects (25 weeks postmenstrual age to 84.8 years) were available for population PK analysis (NON-MEM, two-compartment model for M and two additional compartments for M1). Covariates were weight, age, sex, disease (healthy/patient) and CYP2D6 genotype score. A sigmoid maturation model was used to describe changes in M (CLPO + CLPM), M1 formation (CLPM) and M1 elimination (CLMO) clearance. Phenotype-based and genotype-based models were used to distinguish poor CLPM subjects.


Differences in M disposition between children and adults were largely accounted for by maturation and size. CKLPM (TM50 40.3 weeks, Hill 9.09) and CLPO (TM50 39.1 weeks, Hill 5.8) display fast maturation, while CLMO matures slower. The phenotype-based mixture model estimated that 8.6 were slow metabolizers (18.3% of normal CLPM). Genotype-based estimates were also lower (68%) but not all subjects with a low CYP2D6 score were in the poor metabolizer group.


Maturation of M elimination occurs early with 50% of adult values at full-term age. Maturation and age are key predictors, while CYP2D6 genotype score only explains some of the variability in M disposition.

Authors’ Affiliations

University Hospitals Leuven, Belgium
University of Bonn, Germany
University of Auckland, New Zealand
Hopital Lapeyronie, Montpellier, France
University of Navarra, Pamplona, Spain
University of Southern Denmark, Odense, Denmark


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© Allegaert et al. 2011

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.