Most of the affected individuals are older females with hypertension who are being treated with agents known to affect renal perfusion.
Several Web sites, including those of the Food & Drug Administration and the consumer advocacy organization Public Citizen, have posted warnings about the underrecognized association between sodium phosphate-containing bowel cleansing products, used in preparation for colonoscopies, and chronic kidney failure.
The FDA has indicated that in nearly all of the recent cases, the OSP product used was Phospho-soda (monobasic sodium phosphate monohydrate, dibasic sodium phosphate heptahydrate), which the manufacturer, C.B. Fleet Co., claims is the "leading bowel purgative." Visicol (sodium phosphate, dibasic, anhydrous, sodium phosphate, monobasic, monohydrate) tablets, by Salix Pharmaceuticals, was the product used by one of the 21 patients described in the Journal of the American Society of Nephrology. The bowel cleansing doses of Phospho-soda (two 45-ml doses taken 10 to 12 hours apart) and Visicol (40 tablets) are known to provide nearly identical amounts of sodium phosphate-about 60 gm per dose.