Types of kidney injuries have been reported with the prescription products Visicol and OsmoPrep, and also over-the-counter sodium phosphate products when they are used as bowel cleansers.

FDA first warned about this problem in 2006, but cases of kidney injury continue to be reported. So FDA is requiring the manufacturer of Visicol and OsmoPrep to take several steps. First, a boxed warning about the risk of acute phosphate nephropathy will be added to the product label. The manufacturer will also conduct a new clinical trial to further study the risk of acute kidney injury with these products, provide a Medication Guide for patients, and implement a risk evaluation and mitigation strategy to ensure that the benefits of using these products outweigh their risks.

FDA believes that oral sodium phosphate products should be available only by prescription when they are used for bowel cleansing. Because of this, C.B. Fleet Company has voluntarily recalled the company's oral sodium phosphate products sold over the counter, (Fleet Phospho-soda and Fleet EZ-PREP) and has advised healthcare professionals not to instruct patients to use these products for bowel cleansing. Unico Holdings, Inc. is also recalling its OTC oral sodium phosphate products sold for bowel cleansing.

Health care professionals should use caution when prescribing Visicol or OsmoPrep for patients who may be at higher risk of kidney injury. This includes those over age 55, or those who have kidney disease, bowel obstruction, active colitis, or are dehydrated. It also includes patients taking drugs that affect renal perfusion or function such as diuretics, ACE inhibitors, angiotensin receptor blockers (ARBs) and possibly NSAIDS.

Prescribers should instruct patients about how to prepare for their procedures, and tell them to avoid dehydration by drinking enough clear liquids before, during and after bowel preparation. They should also tell patients to be alert for symptoms of acute kidney injury, including malaise, lethargy, drowsiness, decreased urine volume and swelling of the ankles, feet and legs.

Oral Sodium Phosphate (OSP) products for bowel cleansing

FDA has become aware of reports of acute phosphate nephropathy, a type of acute kidney injury, associated with the use of oral sodium phosphate products (OSP) for bowel cleansing prior to colonoscopy or other procedures. These products include the prescription products, Visicol and OsmoPrep, and OSPs available over-the-counter without a prescription as laxatives (e.g., Fleet Phospho-soda).

In some cases when used for bowel cleansing, these serious adverse events have occurred in patients without identifiable factors that would put them at risk for developing acute kidney injury.

FDA is requiring the manufacturer of Visicol and OsmoPrep, the two OSPs available by prescription only, to add a boxed warning to the labeling for these products. FDA recommends, in light of the risk of acute phosphate nephropathy, over-the-counter laxative OSP products should not be used for bowel cleansing. Consumers should only use OSPs for bowel cleansing pursuant to a prescription from a healthcare professional.