Risks of OSP and Kidneys Articulated One Year Before FDA Alert

San Diego, CAA group that knows a lot about oral sodium phosphate and OSP kidney damage recently wrapped up its 42nd annual conference in San Diego. The yearly meeting and scientific exposition, dubbed "Renal Week" by the American Society of Nephrology (ASN), took place from October 27th to November 1st.


It was in the fall of 2007 that Renal Week attendees first started hearing concerns emerging around diagnostic preparations used to cleanse the bowel prior to colonoscopy. The preparations were identified as causing cancer of the kidney.

Dr. Glen Markowitz of Columbia University presented on the risks of acute and chronic renal failure related to the use of OSPs—specifically, the possibility of the rare, but serious, acute phosphate nephropathy (APN).

That was a year before the US Food and Drug Administration, in concert with various manufacturers, issued a black box warning on prescription versions of OSPs. CB Fleet, which manufactured an over-the-counter (OTC) version of the product, pulled Fleet Phospho-soda from the market entirely. A companion product called Fleet Phospho-soda EZ-Prep Bowel Cleansing System was also pulled.

Prior to the removal of the Fleet OTC product from store shelves, the FDA had recommended that Fleet Phospho-soda be used only as a laxative and not for bowel cleansing.

The FDA based its recommendation on about 20 reports of acute phosphate nephropathy that were linked to the use of oral phosphates. It is not known if the agency was aware of the material presented by the ASN during Renal Week the previous year.

However, the FDA was aware in 2002 that the OSP Viscol was associated with seizures.

What does APN feel like?

According to the National Kidney Foundation, symptoms of acute phosphate nephropathy include lethargy and drowsiness, decreased urine flow and the swelling of ankles, feet and legs. The Foundation cautions, however, that APN patients may not have any identifiable symptoms early on.

Oral sodium phosphates clear the bowel by making bowel movements frequent, loose, and runny. These agents work by causing fluid loss. Patients are required to drink large quantities of clear liquids as part of the bowel preparation.

Little wonder that among the groups identified as being at a higher risk for the development of APN, people who are dehydrated number at the top. Other high-risk groups include patients over the age of 55, those taking various medications, and people who suffer from bowel obstruction, delayed bowel emptying or active colitis.