Flushing out kidney damage
The most unpleasant part of having a colonoscopy, most people agree, is flushing out their bowels beforehand. Now it turns out that that flushing may also be the most dangerous part of the process, posing a risk of acute kidney injury.
The Food and Drug Administration said Thursday that it will require the manufacturer of two of the most commonly used prescription flushing products, Visicol and OsmoPrep,to put a "black box" warning on their labels -- the most severe warning possible. The agency also directed the maker, Salix Pharmaceuticals Ltd., to conduct a post-marketing clinical trial to further assess the risk of the products.
FDA said it will also reassess the labeling of similar over-the-counter products, such as Fleet Phospho-soda, which are thought to have the same risks. Black box warnings are not used for OTC products, but the agency can force manufacturers to change their labels in other ways. In the meantime, FDA cautioned consumers against using OTC cleansing products.
The new warning will caution about using the drugs in:
- people over age 55;
- people who already suffer from dehydration, kidney disease, acute colitis or delayed bowel emptying; and
- people taking medicines that affect kidney function.
The problems appear to arise when people using the products become severely dehydrated, which damages the kidneys. Current labels indicate that people should drink a half-gallon of water when taking the drugs, but many people don't. "Some patients that take these pills feel that perhaps you don't need to drink as much as you really do to avoid these side effects," Dr. Joyce Korvick, director of FDA's digestive products division, said at a news conference.
Other bowel cleaners now in use are liquids that contain polyethylene glycol, but the agency stopped short of recommending them as an alternative. Patients taking those must consume two to three gallons of water with them, and that is even harder, Korvick said.
FDA sent a letter to physicians in 2006 warning about the potential problems with the drugs. Since then, Korvick said, the agency has received 20 reports of kidney problems associated with OsmoPrep.
-- Thomas H. Maugh II
