Oral Sodium Phosphate Products Linked to Kidney Disease

Oral Sodium Phosphate Products Linked to Rare Risk for Acute Nephropathy

Yael Waknine

Medscape 2006.

May 8, 2006 ?- The US Food and Drug Administration (FDA) has notified healthcare professionals regarding the rare risk for acute phosphate nephropathy associated with use of oral sodium phosphate (OSP) products for bowel cleansing.

The condition has been documented in 21 patients who had used an OSP solution (such as Fleet Phospho-soda or ACCU-PREP, made by C.B. Fleet Company, Inc), and 1 patient who had taken OSP tablets (Visicol, made by Salix Pharmaceuticals, Inc), according to an alert sent Friday from MedWatch, the FDA's safety information and adverse event reporting program.

Of the 21 cases, 17 occurred in women; 13 patients were aged 62 years or older; 14 were receiving treatment with angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs); 4 patients were using a diuretic; and 3 were taking nonsteroidal anti-inflammatory drugs (NSAIDs). Baseline creatinine levels were normal in 17 patients and mild elevations (1.3 - 1.7 mg/dL) were observed in 4 patients.

Eighteen of 21 patients were diagnosed with acute renal failure within 2 months of colonoscopy; all were diagnosed within 5 months. At a mean 16.7 months postbiopsy, 4 patients were on hemodialysis and 17 patients had chronic renal failure (mean serum creatinine, 2.4 mg/dL).

The FDA notes that cases of renal failure in patients receiving OSP solution (n = 10) and tablets (n = 10) have also been reported via MedWatch. No reports of acute phosphate nephropathy or acute renal failure have been associated with the recently approved sodium phosphate monobasic monohydrate plus sodium phosphate dibasic anhydrous tablets (OsmoPrep, made by Salix Pharmaceuticals, Inc).

Because of the increased risk for acute phosphate nephropathy, the FDA advises against use of OSP products in patients with kidney disease, impaired renal function or perfusion, dehydration, or uncorrected electrolyte abnormalities.

Caution should be used when prescribing OSP products for patients taking medications that may affect renal perfusion or function, such as diuretics, ACE inhibitors, ARBs, and NSAIDs.

When using OSP products for bowel cleansing, recommended doses should not be exceeded and concomitant use of sodium phosphate-containing laxatives should be avoided. Patients should be encouraged to take the correct OSP dose and drink sufficient quantities of clear fluids during bowel cleansing.

The FDA notes that use of electrolyte rehydration solutions may potentially decrease the risk for electrolyte abnormalities and hypovolemia associated with bowel cleansing.

Patients at increased risk for acute phosphate nephropathy and those with vomiting and/or signs of dehydration should be monitored using baseline and postprocedure laboratory tests, including those that measure electrolyte, calcium, phosphate, BUN, and creatinine levels.

For frail patients who may be unable to consume appropriate quantities of fluids or lack assistance at home, hospitalization and supportive intravenous hydration should be considered.

Adverse events associated with the use of oral sodium phosphate products should be reported to the FDA's MedWatch reporting program by phone at 1-800-FDA-1088, by fax at 1-800-FDA-0178, online at http://www.fda.gov/medwatch, or by mail to 5600 Fishers Lane, Rockville, MD 20852-9787.