Abuse of guaifenesin-containing medications generates an excess of a carboxylate salt of beta-(2-methoxyphenoxy)-lactic acid, a guaifenesin metabolite, and results in urolithiasis

Pickens, Cynthia L; Milliron, Abby R; Fussner, Alice L; Dversdall, Bart C; Langenstroer, Peter; Ferguson, Scott; Fu, Xiong; Schmitz, Francis J; Poole, Edward C

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Volume 54, Issue 1 , Pages 23-27, July 1999

Abuse of guaifenesin-containing medications generates an excess of a carboxylate salt of beta-(2-methoxyphenoxy)-lactic acid, a guaifenesin metabolite, and results in urolithiasis

Cynthia L Pickens
- UroSciences Group, UroCor, Inc., Oklahoma City, Oklahoma, USA
- Reprint requests: Cynthia L. Pickens, M.S., UroSciences Group, UroCor, Inc., 800 Research Parkway, Oklahoma City, OK 73104
Abby R Milliron
- UroSciences Group, UroCor, Inc., Oklahoma City, Oklahoma, USA
Alice L Fussner
- UroSciences Group, UroCor, Inc., Oklahoma City, Oklahoma, USA
Bart C Dversdall
- UroSciences Group, UroCor, Inc., Oklahoma City, Oklahoma, USA
Peter Langenstroer
- Division of Urology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
Scott Ferguson
- Department of Urology, University of Arkansas, College of Medicine, Little Rock, Arkansas, USA
Xiong Fu
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
Francis J Schmitz
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
Edward C Poole
- UroSciences Group, UroCor, Inc., Oklahoma City, Oklahoma, USA

Received 2 November 1998; received in revised form 5 January 1999; accepted 5 January 1999.

Abstract

Objectives. Several urinary calculi were submitted to our institution for compositional analysis. The typical techniques of analysis, polarized light microscopy, electron microprobe analysis, and infrared spectroscopy proved inadequate for a definitive identification. As a result, a more detailed organic analysis was conducted to determine the exact chemical structure of the material.

Methods. Infrared spectroscopy and mass spectrometric analysis were carried out on the solid material, providing information concerning the functional groups and the molecular mass of the organic constituent and its components. The stone was solubilized in deuterated solvents and analyzed by nuclear magnetic resonance spectroscopy, which resulted in a definitive chemical structure.

Results. The spectroscopic analysis indicated that the stones were composed of a calcium salt of beta-(2-methoxyphenoxy)-lactic acid, a metabolite of the pharmaceutical guaifenesin, which is used as an expectorant.

Conclusions. Guaifenesin, an expectorant common in over-the-counter cold and allergy remedies, can cause urolithiasis if taken in excess. Discussions with physicians and their patients confirmed that most patients admitted to taking large doses of guaifenesin-containing medications.