The U.S. Food and Drug Administration will be adding “black-box warnings” on two prescription drugs used to cleanse the bowel before a colonoscopy because they may cause kidney damage.
The black-box warnings, the agency’s strictest warning, will apply to OsmoPrep and Visicol -- prescription oral sodium phosphate (OSP) products -- and warn consumers about the associated risk of acute phosphate nephropathy – a type of kidney injury.
“The agency has received more than 20 cases of kidney failure associated with OsmoPrep,” Dr. Joyce Korvick, director of FDA's digestive products. “Three cases of acute phosphate nephropathy were confirmed by biopsy. The onset of kidney injury occurred within three hours of use in some cases and in others up to 21 days after use.”
The agency also received reports of 19 cases of acute renal (kidney) failure. Seven of which were confirmed by biopsy.
The FDA is requiring the products’ manufacturer, Salix Pharmaceuticals, to distribute a medication guide warning patients about the risks of the drugs. The company must also conduct a post-marketing clinical trial to assess the injury risk.
Similar over-the-counter (OTC) bowel cleansing products, such as Fleet Phospho-soda, will also get new warnings.
Patients usually take over-the-counter and prescription OSP products to clean the bowel before medical procedures including a colonoscopy.
Alternative bowel cleansing treatments include GoLytely and HalfLytely Bowel Prep, she added.
“We do not believe all patients are at risk,” said Charles Ganley, MD, director of the FDA’s Office of Nonprescription Products. “Most patients who use these products do not have any complications.”
One reason for the risk might be that some people are dehydrated and may not be drinking enough fluid when using OSP products, despite directions on the products, said Korvick.
OSP products should not be used in combination with other laxatives containing sodium phosphate and in children younger than 18. The high-risk groups outlined below, are urged to use OSP products with the caution:
-- People 55 and older
-- People that suffer from dehydration, kidney disease, acute colitis, or delayed bowel emptying
-- And those who take certain drugs that affect kidney function, such as diuretics, ACE inhibitors, angiotensin receptor blockers and anti-inflammatory drugs (NSAIDs) such as ibuprofen and Naproxen.
The American Cancer Society ranks colorectal cancer third in the U.S. in terms of cancer diagnoses among men and women. 153,000 cases of colon and rectal cancer are expected to be diagnosed, this year. And, about 50,000 of them will die from the disease. #