FDA Puts Black-Box Warning on Bowel-Cleansing Drugs

Dec. 12 -- THURSDAY, Dec. 11 (HealthDay News) -- Two prescription drugs used to cleanse the bowel before a colonoscopy may cause kidney damage, the U.S. Food and Drug Administration said Thursday.

The FDA said it would now require a black-box warning on the oral sodium phosphate products Visicol and OsmoPrep, alerting consumers about the risk of acute phosphate nephropathy -- a type of severe kidney injury.

"The FDA has received reports of 20 unique cases of kidney injury associated with the use of OsmoPrep," Dr. Joyce Korvick, deputy director of FDA's Division of Gastroenterology Products at the Center for Drug Evaluation and Research, said during an afternoon teleconference. "Of the reported cases, three were biopsy-proven cases of acute phosphate nephropathy. The onset of kidney injury in these cases varied, occurring in some within several hours of use of these products and in other cases up to 21 days after use."

The agency said it has told the products' manufacturer, Salix Pharmaceuticals of Morrisville, N.C., to develop what's called a risk evaluation and mitigation strategy, to distribute a medication guide for patients so they're aware of the risk of kidney injury, and to conduct a post-marketing clinical trial to gauge the risk of injury.

The FDA also said it was concerned about similar non-prescription treatments, such as Fleet Phospho-soda, made by C.B. Fleet Co. of Lynchburg, Va. These treatments also shouldn't be used for bowel cleansing, and will get new warnings. At lower doses, however, they are safe for use as laxatives, the FDA said.

Patients routinely take oral sodium phosphate products -- either prescription or over the counter -- to clean the intestines before a colonoscopy and other medical procedures.

"The FDA is recommending that consumers not use the over-the-counter preparations for bowel cleansing, but that these products be used under the direction of a physician," Korvick said.

She added that there are alternatives to these preparations that can be used for bowel cleansing, including GoLYTELY and HalfLytely Bowel Prep.