Clinical Pharmacokinetics

, Volume 57, Issue 5, pp 577–589 | Cite as

Improving Pediatric Protein Binding Estimates: An Evaluation of α1-Acid Glycoprotein Maturation in Healthy and Infected Subjects

  • Anil R. Maharaj
  • Daniel Gonzalez
  • Michael Cohen-Wolkowiez
  • Christoph P. Hornik
  • Andrea N. Edginton
Original Research Article



Differences in plasma protein levels observed between children and adults can alter the extent of xenobiotic binding in plasma, resulting in divergent patterns of exposure.


This study aims to quantify the ontogeny of α1-acid glycoprotein in both healthy and infected subjects.


Data pertaining to α1-acid glycoprotein from healthy subjects were compiled over 26 different publications. For subjects diagnosed or suspected of infection, α1-acid glycoprotein levels were obtained from 214 individuals acquired over three clinical investigations. The analysis evaluated the use of linear, power, exponential, log-linear, and sigmoid E max models to describe the ontogeny of α1-acid glycoprotein. Utility of the derived ontogeny equation for estimation of pediatric fraction unbound was evaluated using average-fold error and absolute average-fold error as measures of bias and precision, respectively. A comparison to fraction unbound estimates derived using a previously proposed linear equation was also instituted.


The sigmoid E max model provided the comparatively best depiction of α1-acid glycoprotein ontogeny in both healthy and infected subjects. Despite median α1-acid glycoprotein levels in infected subjects being more than two-fold greater than those observed in healthy subjects, a similar ontogeny pattern was observed when levels were normalized toward adult levels. For estimation of pediatric fraction unbound, the α1-acid glycoprotein ontogeny equation derived from this work (average fold error 0.99; absolute average fold error 1.24) provided a superior predictive performance in comparison to the previous equation (average fold error 0.74; absolute average fold error 1.45).


The current investigation depicts a proficient modality for estimation of protein binding in pediatrics and will, therefore, aid in reducing uncertainty associated with pediatric pharmacokinetic predictions.



The AAG data taken from subjects with diagnosed or suspected infections were collected through the Pediatric Trials Network, which is sponsored by the National Institute of Child Health and Human Development (NICHD) contract HHSN275201000003I (PI: Benjamin). The data were collected through three separate trials: HHSN27500013 (PI: Benjamin) for the Pharmacokinetics of Antistaphylococcal Antibiotics in Infants study (Staph Trio; protocol NICHD-2012-STA01); HHSN27500006 (PI: Melloni, Cohen-Wolkowiez) for the Pharmacokinetics of Understudied Drugs Administered to Children per Standard of Care Study (PTN POPS; protocol NICHD-2011-POP01); and HHSN27500018 (PI: Watt) for the Safety and Pharmacokinetics of Multiple-Dose Intravenous and Oral Clindamycin in Pediatric Subjects with BMI ≥85th Percentile study (CLIN01; protocol NICHD-2012-CLN01).

Compliance with Ethical Standards


No sources of funding were received for the preparation of this study.

Conflict of interest

A.R.M. is supported by the Natural Sciences and Engineering Research Council of Canada. A.N.E receives support for research from the National Institutes of Health [NIH] (1R01-HD076676-01A1, PI: M.C.W.). D.G. is funded by K23HD083465 from the National Institute for Child Health and Human Development and by the nonprofit Thrasher Research Fund ( C.P.H receives salary support for research from the National Center for Advancing Translational Sciences of the NIH (UL1TR001117). M.C.W. receives support for research from the NIH (1R01-HD076676-01A1), the National Center for Advancing Translational Sciences of the NIH (UL1TR001117), the National Institute of Allergy and Infectious Disease (HHSN272201500006I and HHSN272201300017I), the National Institute for Child Health and Human Development of the NIH (HHSN275201000003I), the Food and Drug Administration (1U01FD004858-01), the Biomedical Advanced Research and Development Authority (HHSO100201300009C), the nonprofit organization Thrasher Research Fund (, and from industry for drug development in adults and children (


  1. 1.
    Benet LZ, Hoener BA. Changes in plasma protein binding have little clinical relevance. Clin Pharmacol Ther. 2002;71(3):115–21.CrossRefPubMedGoogle Scholar
  2. 2.
    McNamara PJ, Alcorn J. Protein binding predictions in infants. AAPS Pharm Sci. 2002;4(1):E4.CrossRefGoogle Scholar
  3. 3.
    Routledge PA. The plasma protein binding of basic drugs. Br J Clin Pharmacol. 1986;22(5):499–506.CrossRefPubMedPubMedCentralGoogle Scholar
  4. 4.
    Edginton AN, Ritter L. Predicting plasma concentrations of bisphenol A in children younger than 2 years of age after typical feeding schedules, using a physiologically based toxicokinetic model. Environ Health Perspect. 2009;117(4):645–52.CrossRefPubMedGoogle Scholar
  5. 5.
    Trainor GL. The importance of plasma protein binding in drug discovery. Expert Opin Drug Discov. 2007;2(1):51–64.CrossRefPubMedGoogle Scholar
  6. 6.
    Ascenzi P, Fanali G, Fasano M, Pallottini V, Trezza V. Clinical relevance of drug binding to plasma proteins. J Mol Struct. 2014;1077:4–13.CrossRefGoogle Scholar
  7. 7.
    Huang Z, Ung T. Effect of alpha-1-acid glycoprotein binding on pharmacokinetics and pharmacodynamics. Curr Drug Metab. 2013;14(2):226–38.PubMedGoogle Scholar
  8. 8.
    Fournier T, Medjoubi NN, Porquet D. Alpha-1-acid glycoprotein. Biochim Biophys Acta. 2000;1482(1–2):157–71.CrossRefPubMedGoogle Scholar
  9. 9.
    Schonfeld DL, Ravelli RB, Mueller U, Skerra A. The 1.8-A crystal structure of alpha1-acid glycoprotein (Orosomucoid) solved by UV RIP reveals the broad drug-binding activity of this human plasma Lipocalin. J Mol Biol. 2008;384(2):393–405.CrossRefPubMedGoogle Scholar
  10. 10.
    Jolliet-Riant P, Boukef MF, Duche JC, Simon N, Tillement JP. The genetic variant A of human alpha 1-acid glycoprotein limits the blood to brain transfer of drugs it binds. Life Sci. 1998;62(14):PL219–26.CrossRefPubMedGoogle Scholar
  11. 11.
    Eap CB, Cuendet C, Baumann P. Binding of d-methadone, l-methadone, and dl-methadone to proteins in plasma of healthy volunteers: role of the variants of alpha 1-acid glycoprotein. Clin Pharmacol Ther. 1990;47(3):338–46.CrossRefPubMedGoogle Scholar
  12. 12.
    Herve F, Gomas E, Duche JC, Tillement JP. Evidence for differences in the binding of drugs to the two main genetic variants of human alpha 1-acid glycoprotein. Br J Clin Pharmacol. 1993;36(3):241–9.CrossRefPubMedPubMedCentralGoogle Scholar
  13. 13.
    Veering BT, Burm AG, Souverijn JH, Serree JM, Spierdijk J. The effect of age on serum concentrations of albumin and alpha 1-acid glycoprotein. Br J Clin Pharmacol. 1990;29(2):201–6.CrossRefPubMedPubMedCentralGoogle Scholar
  14. 14.
    Johnson TN, Rostami-Hodjegan A, Tucker GT. Prediction of the clearance of eleven drugs and associated variability in neonates, infants and children. Clin Pharmacokinet. 2006;45(9):931–56.CrossRefPubMedGoogle Scholar
  15. 15.
    Zegers I, Keller T, Schreiber W, Sheldon J, Albertini R, Blirup-Jensen S, et al. Characterization of the new serum protein reference material Erm-Da470k/Ifcc: value assignment by immunoassay. Clin Chem. 2010;56(12):1880–8.CrossRefPubMedGoogle Scholar
  16. 16.
    Baudner S, Bienvenu J, Blirup-Jensen S, Carlstrom A, Johnson AM, Milford Ward A, et al. The certification of a matrix reference material for immunochemical measurement of 14 human serum proteins Crm 470. Brussels: Community Bureau of References (BCR) of the Commission of the European Communities; 1992: Report No.: BCR/92/92.Google Scholar
  17. 17.
    Whicher JT, Ritchie RF, Johnson AM, Baudner S, Bienvenu J, Blirup-Jensen S, et al. New international reference preparation for proteins in human serum (RPPHS). Clin Chem. 1994;40(6):934–8.PubMedGoogle Scholar
  18. 18.
    Behr W, Schlimok G, Firchau V, Paul HA. Determination of reference intervals for 10 serum proteins measured by rate nephelometry, taking into consideration different sample groups and different distribution functions. J Clin Chem Clin Biochem. 1985;23(3):157–66.PubMedGoogle Scholar
  19. 19.
    Röst G, Vizi Z, Kiss IZ. Impact of non-Markovian recovery on network epidemics. In: Mondaini RP, editor. Biomat 2015: proceedings of the International Symposium on Mathematical and Computational Biology. Singapore: World Scientific; 2016. p. 40–53.CrossRefGoogle Scholar
  20. 20.
    Kanakoudi F, Drossou V, Tzimouli V, Diamanti E, Konstantinidis T, Germenis A, et al. Serum concentrations of 10 acute-phase proteins in healthy term and preterm infants from birth to age 6 months. Clin Chem. 1995;41(4):605–8.PubMedGoogle Scholar
  21. 21.
    Malvy DJ, Poveda JD, Debruyne M, Montagnon B, Burtschy B, Herbert C, et al. Laser immunonephelometry reference intervals for eight serum proteins in healthy children. Clin Chem. 1992;38(3):394–9.PubMedGoogle Scholar
  22. 22.
    Ott WR. Environmental statistics and data analysis. Boca Raton: Taylor & Francis; 1994.Google Scholar
  23. 23.
    Sann L, Bienvenu J, Lahet C, Divry P, Cotte J, Bethenod M. Serum orosomucoid concentration in newborn infants. Eur J Pediatr. 1981;136(2):181–5.CrossRefPubMedGoogle Scholar
  24. 24.
    Bonate PL. Pharmacokinetic-pharmacodynamic modeling and simulation. 2nd ed. New York (NY): Springer; 2011.CrossRefGoogle Scholar
  25. 25.
    Gonzalez D, Delmore P, Bloom BT, Cotten CM, Poindexter BB, McGowan E, et al. Clindamycin pharmacokinetics and safety in preterm and term infants. Antimicrob Agents Chemother. 2016;60(5):2888–94.CrossRefPubMedPubMedCentralGoogle Scholar
  26. 26.
    Gonzalez D, Melloni C, Yogev R, Poindexter BB, Mendley SR, Delmore P, et al. Use of opportunistic clinical data and a population pharmacokinetic model to support dosing of clindamycin for premature infants to adolescents. Clin Pharmacol Ther. 2014;96(4):429–37.CrossRefPubMedPubMedCentralGoogle Scholar
  27. 27.
    Smith MJ, Gonzalez D, Goldman JL, Yogev R, Sullivan JE, Reed MD, et al. Pharmacokinetics of clindamycin in obese and nonobese children. Antimicrob Agents Chemother. 2017;61(4):e02014–6. doi: 10.1128/AAC.02014-16.CrossRefPubMedPubMedCentralGoogle Scholar
  28. 28.
    Lin LI. A concordance correlation coefficient to evaluate reproducibility. Biometrics. 1989;45(1):255–68.CrossRefPubMedGoogle Scholar
  29. 29.
    Asali LA, Brown KF. Naloxone protein binding in adult and foetal plasma. Eur J Clin Pharmacol. 1984;27(4):459–63.CrossRefPubMedGoogle Scholar
  30. 30.
    Ballou SP, Lozanski FB, Hodder S, Rzewnicki DL, Mion LC, Sipe JD, et al. Quantitative and qualitative alterations of acute-phase proteins in healthy elderly persons. Age Ageing. 1996;25(3):224–30.CrossRefPubMedGoogle Scholar
  31. 31.
    Belpaire FM, Wynant P, Van Trappen P, Dhont M, Verstraete A, Bogaert MG. Protein binding of propranolol and verapamil enantiomers in maternal and foetal serum. Br J Clin Pharmacol. 1995;39(2):190–3.CrossRefPubMedPubMedCentralGoogle Scholar
  32. 32.
    Bendayan R, Pieper JA, Stewart RB, Caranasos GJ. Influence of age on serum protein binding of propranolol. Eur J Clin Pharmacol. 1984;26(2):251–4.CrossRefPubMedGoogle Scholar
  33. 33.
    Bienvenu J, Sann L, Bienvenu F, Lahet C, Divry P, Cotte J, et al. Laser nephelometry of orosomucoid in serum of newborns: reference intervals and relation to bacterial infections. Clin Chem. 1981;27(5):721–6.PubMedGoogle Scholar
  34. 34.
    Blain PG, Mucklow JC, Rawlins MD, Roberts DF, Routledge PA, Shand DG. Determinants of plasma alpha 1-acid glycoprotein (Aag) concentrations in health. Br J Clin Pharmacol. 1985;20(5):500–2.CrossRefPubMedPubMedCentralGoogle Scholar
  35. 35.
    Davis D, Grossman SH, Kitchell BB, Shand DG, Routledge PA. The effects of age and smoking on the plasma protein binding of lignocaine and diazepam. Br J Clin Pharmacol. 1985;19(2):261–5.CrossRefPubMedPubMedCentralGoogle Scholar
  36. 36.
    Kawerk N, Succari-Aderschlag M, Foglietti MJ. Microheterogeneity of alpha 1-acid glycoprotein in healthy elderly subjects: patterns obtained by crossed affino-immunoelectrophoresis. Clin Chim Acta. 1991;202(1–2):65–72.CrossRefPubMedGoogle Scholar
  37. 37.
    Kishino S, Nomura A, Di ZS, Sugawara M, Iseki K, Kakinoki S, et al. Alpha-1-acid glycoprotein concentration and the protein binding of disopyramide in healthy subjects. J Clin Pharmacol. 1995;35(5):510–4.CrossRefPubMedGoogle Scholar
  38. 38.
    Lee SK, Thibeault DW, Heiner DC. Alpha 1-antitrypsin and alpha 1-acid glycoprotein levels in the cord blood and amniotic fluid of infants with respiratory distress syndrome. Pediatr Res. 1978;12(7):775–7.CrossRefPubMedGoogle Scholar
  39. 39.
    Lerman J, Strong HA, LeDez KM, Swartz J, Rieder MJ, Burrows FA. Effects of age on the serum concentration of alpha 1-acid glycoprotein and the binding of lidocaine in pediatric patients. Clin Pharmacol Ther. 1989;46(2):219–25.CrossRefPubMedGoogle Scholar
  40. 40.
    Meistelman C, Benhamou D, Barre J, Levron JC, Mahe V, Mazoit X, et al. Effects of age on plasma protein binding of sufentanil. Anesthesiology. 1990;72(3):470–3.CrossRefPubMedGoogle Scholar
  41. 41.
    Meuldermans W, Woestenborghs R, Noorduin H, Camu F, van Steenberge A, Heykants J. Protein binding of the analgesics alfentanil and sufentanil in maternal and neonatal plasma. Eur J Clin Pharmacol. 1986;30(2):217–9.CrossRefPubMedGoogle Scholar
  42. 42.
    Milman N, Graudal N, Andersen HC. Acute phase reactants in the elderly. Clin Chim Acta. 1988;176(1):59–62.CrossRefPubMedGoogle Scholar
  43. 43.
    Philip AG, Hewitt JR. Alpha 1-acid glycoprotein in the neonate with and without infection. Biol Neonate. 1983;43(3–4):118–24.CrossRefPubMedGoogle Scholar
  44. 44.
    Pressac M, Vignoli L, Aymard P, Ingenbleek Y. Usefulness of a prognostic inflammatory and nutritional index in pediatric clinical practice. Clin Chim Acta. 1990;188(2):129–36.CrossRefPubMedGoogle Scholar
  45. 45.
    Raubenstine DA, Ballantine TV, Greecher CP, Webb SL. Neonatal serum protein levels as indicators of nutritional status: normal values and correlation with anthropometric data. J Pediatr Gastroenterol Nutr. 1990;10(1):53–61.CrossRefPubMedGoogle Scholar
  46. 46.
    Routledge PA, Stargel WW, Kitchell BB, Barchowsky A, Shand DG. Sex-related differences in the plasma protein binding of lignocaine and diazepam. Br J Clin Pharmacol. 1981;11(3):245–50.CrossRefPubMedPubMedCentralGoogle Scholar
  47. 47.
    Succari M, Foglietti MJ, Percheron F. Microheterogeneity of alpha 1-acid glycoprotein: variation during the menstrual cycle in healthy women, and profile in women receiving estrogen-progestogen treatment. Clin Chim Acta. 1990;187(3):235–41.CrossRefPubMedGoogle Scholar
  48. 48.
    Winkel P, Statland BE, Nielsen MK. Biologic and analytic components of variation of concentration values of selected serum proteins. Scand J Clin Lab Invest. 1976;36(6):531–7.CrossRefPubMedGoogle Scholar
  49. 49.
    Wilson AS, Stiller RL, Davis PJ, Fedel G, Chakravorti S, Israel BA, et al. Fentanyl and alfentanil plasma protein binding in preterm and term neonates. Anesth Analg. 1997;84(2):315–8.CrossRefPubMedGoogle Scholar
  50. 50.
    Gotoh H, Ishikawa N, Shioiri T, Hattori Y, Nomura H, Ogawa J. Diagnostic significance of serum orosomucoid level in bacterial infections during neonatal period. Acta Paediatr Scand. 1973;62(6):629–32.CrossRefGoogle Scholar
  51. 51.
    Maharaj AR, Edginton AN. Physiologically based pharmacokinetic modeling and simulation in pediatric drug development. CPT Pharmacometr Syst Pharmacol. 2014;3:e150.CrossRefGoogle Scholar
  52. 52.
    Benedek IH, Blouin RA, McNamara PJ. Serum protein binding and the role of increased alpha 1-acid glycoprotein in moderately obese male subjects. Br J Clin Pharmacol. 1984;18(6):941–6.CrossRefPubMedPubMedCentralGoogle Scholar
  53. 53.
    Rowland M, Tozer NT. Clinical pharmacokinetics and pharmacodynamics: concepts and applications. 4th ed. Baltimore (MD): Lippincott Williams & Wilkins; 2011.Google Scholar
  54. 54.
    Maharaj AR, Barrett JS, Edginton AN. A workflow example of PBPK modeling to support pediatric research and development: case study with lorazepam. AAPS J. 2013;15(2):455–64.CrossRefPubMedPubMedCentralGoogle Scholar
  55. 55.
    Johnson JA, Livingston TN. Differences between blacks and whites in plasma protein binding of drugs. Eur J Clin Pharmacol. 1997;51(6):485–8.CrossRefPubMedGoogle Scholar
  56. 56.
    Zhou HH, Adedoyin A, Wilkinson GR. Differences in plasma binding of drugs between Caucasians and Chinese subjects. Clin Pharmacol Ther. 1990;48(1):10–7.CrossRefPubMedGoogle Scholar
  57. 57.
    Wakefield J. Ecologic studies revisited. Annu Rev Public Health. 2008;29:75–90.CrossRefPubMedGoogle Scholar

Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  • Anil R. Maharaj
    • 1
  • Daniel Gonzalez
    • 2
  • Michael Cohen-Wolkowiez
    • 3
    • 4
  • Christoph P. Hornik
    • 3
    • 4
  • Andrea N. Edginton
    • 1
  1. 1.School of PharmacyUniversity of WaterlooKitchenerCanada
  2. 2.Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of PharmacyThe University of North Carolina at Chapel HillChapel HillUSA
  3. 3.Department of PediatricsDuke University School of MedicineDurhamUSA
  4. 4.Duke Clinical Research InstituteDuke University School of MedicineDurhamUSA

Personalised recommendations