WebMD Medical News
Louise Chang, MD
Dec. 11, 2008 -- The FDA today ordered a "black box" warning, the
FDA's sternest warning, for the prescription oral sodium phosphate products
Visicol and OsmoPrep, which are used to cleanse the bowel before a colonoscopy
and other medical procedures.
The warning pertains to the risk of acute phosphate nephropathy, which is a
type of acute kidney injury.
The FDA also recommends that consumers not use over-the-counter oral sodium
phosphate products, such as Fleet Phospho-soda, for bowel cleansing.
According to the FDA, over-the-counter oral sodium phosphate products, when
used for bowel cleansing, pose the same kidney risk as the prescription oral
sodium phosphate products. But that risk doesn't apply to those
over-the-counter products used as laxatives.
The FDA has received 20 reports of kidney injury associated with OsmoPrep
since OsmoPrep's approval in 2006. Three of those cases were confirmed by
biopsy. Some cases happened within hours of use; others were reported days or
The FDA has also received reports of 19 cases of acute renal (kidney)
failure, seven of which were confirmed by biopsy.
Korvik notes that one reason for the risk might be that some people may be
dehydrated and not drinking enough fluid when they use oral sodium phosphate
products for bowel cleansing, despite the instructions on the products.
"We don't believe that all of the patients are at risk," Korvik said
at a news conference.
Charles Ganley, MD, who directs the FDA's Office of Nonprescription
Products, agrees, noting that "the majority" of patients who use those
products "don't run into problems."
The FDA has asked Salix Pharmaceuticals, which makes Visicol and OsmoPrep,
to do a study to learn more about the kidney risk and how to manage it.
Spokespeople for Salix Pharmaceuticals and for C.B. Fleet Company, which
makes Fleet Phospho-soda, were not immediately available for comment.
Patients 18 and older can still use Visicol and OsmoPrep for bowel cleansing
before colonoscopy or other procedures.
But the FDA recommends that people use caution with those products if they
are in the following risk groups:
The FDA's warning doesn't apply to Golytely, Colyte, Nulytely, Trilyte, and
Halflytely, which are polyethylene glycol preparations that can be used for
SOURCES:News release, FDA.Joyce Korvik, MD, deputy director, Division of Gastroenterology Products,
Center for Drug Evaluation and Research, FDA.Charles Ganley, MD, director, Office of Nonprescription Products, Center for
Drug Evaluation and Research, FDA.
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