Toxicological Reviews

, Volume 22, Issue 3, pp 129–136

Does Urine Alkalinization Increase Salicylate Elimination? If so, Why?

  • Alex T. Proudfoot
  • Edward P. Krenzelok
  • Jeffrey Brent
  • J. Allister Vale
Review Article

DOI: 10.2165/00139709-200322030-00001

Cite this article as:
Proudfoot, A.T., Krenzelok, E.P., Brent, J. et al. Toxicol Rev (2003) 22: 129. doi:10.2165/00139709-200322030-00001

Abstract

Urine alkalinization is a treatment regimen that increases poison elimination by the administration of intravenous sodium bicarbonate to produce urine with a pH ≥7.5. Experimental and clinical studies confirm that urinary alkalinization increases salicylate elimination, although the mechanisms by which this occurs have not been elucidated. The conventional view is that ionisation of a weak acid, such as salicylic acid, is increased in an alkaline environment. Since the ionisation constant (pKa) is a logarithmic function then, theoretically, a small change in urine pH will have a disproportionately larger effect on salicylate clearance. Hence, elimination of salicylic acid by the kidneys is increased substantially in alkaline urine. However, as salicylic acid is almost completely ionised within physiological pH limits, alkalinization of the urine could not, therefore, significantly increase the extent of ionisation further and the conventional view of the mechanism by which alkalinization is effective is patently impossible. Further experimental studies are required to clarify the mechanisms by which urine alkalinization enhances salicylate elimination.

Copyright information

© Adis Data Information BV 2003

Authors and Affiliations

  • Alex T. Proudfoot
    • 1
  • Edward P. Krenzelok
    • 2
  • Jeffrey Brent
    • 3
    • 4
  • J. Allister Vale
    • 1
  1. 1.National Poisons Information Service (Birmingham Centre)City HospitalBirminghamUK
  2. 2.Pittsburgh Poison Center, Children’s Hospital of PittsburghUniversity of Pittsburgh Schools of Pharmacy and MedicinePittsburghUSA
  3. 3.Toxicology AssociatesDenverUSA
  4. 4.University of Colorado Health Sciences CenterDenverUSA

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