Guaifenesin- and ephedrine-induced stones

Purpose: We report a new type of drug-induced stone that is caused by overc onsumption of preparations containing guaifenesin and ephedrine, Materials and Methods: Clinical and stone analysis data from the Molecular Structure Laboratory at the Veterans Affairs Medical Center in Milwaukee, W isconsin, were reviewed. Stone analysis was performed by Fourier transform infrared spectroscopy, high-resolution X-ray crystallographic powder diffra ction, or both. The urine and stone material from one of the subjects were analyzed with high-performance liquid chromatography, Results: Stone analysis from seven patients demonstrated metabolites of gua ifenesin. High-performance liquid chromatography revealed that the stone an d urine from one subject had a high content of guaifenesin metabolites and a small amount of ephedrine, Demographic data were available on five patien ts. Three had a history of alcohol or drug dependency. All were consuming o ver-the-counter preparations containing ephedrine and guaifenesin, Four adm itted to taking excessive quantities of these agents, mainly as a stimulant , Hypocitraturia was identified in two individuals subjected to urinary met abolic testing, These stones are radiolucent on standard X-ray imaging but can be demonstrated on unenhanced CT. Shockwave lithotripsy was performed i n two patients, and the calculi fragmented easily. Conclusions: Individuals consuming large quantities of preparations contain ing ephedrine and guaifenesin may be at risk to develop stones derived main ly from metabolites of guaifenesin and small quantities of ephedrine, These patients may be prone to drug or alcohol dependency.