OsmoPrep increases chances of acute kidney injuries

The FDA issued an alert on December 11th, 2008 stating that it had become aware of reports of acute kidney injury associated with the use of OsmoPrep. This type of kidney injury is known as Acute Phosphate Nephropathy. OsmoPrep is a type of oral sodium phosphate products (OSP) and it is used for bowel cleansing prior to colonoscopy or other procedures. 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. We cannot rule out, however, that some of these patients were dehydrated prior to ingestion of OSPs or they did not drink sufficient fluids after ingesting OSP.

Acute phosphate nephropathy is a form of acute kidney injury that is associated with deposits of calcium-phosphate crystals in the renal tubules that may result in permanent renal function impairment. Acute phosphate nephropathy is a rare, serious adverse event that has been associated with the use of OsmoPrep. The occurrence of these events was previously described in an Information for Healthcare Professionals sheet and an FDA Science Paper issued in May 2006. Additional cases of acute phosphate nephropathy have been reported to FDA and described in the literature since these were issued.

Individuals who appear to have an increased risk of acute phosphate nephropathy following the use of OsmoPrep include persons: who are over age 55; who are hypovolemic or have decreased intravascular volume; who have baseline kidney disease, bowel obstruction, or active colitis; and who are using medications that affect renal perfusion or function (such as diuretics, angiotensin converting enzyme [ACE] inhibitors, angiotensin receptor blockers [ARBs], and possibly nonsteroidal anti-inflammatory drugs [NSAIDs]).

As a result of new safety information received, FDA is requiring the manufacturer of OsmoPrep, Salix Pharmaceuticals, Inc. to add a Boxed Warning to the labeling for this product. FDA is also requiring that the manufacturer develop and implement a risk evaluation and mitigation strategy (REMS), which will include a Medication Guide, to ensure that the benefits of OsmoPrep outweighs the risk of acute phosphate nephropathy, and to conduct a postmarketing clinical trial to further assess the risk of acute kidney injury with use of OsmoPrep.