The Food and Drug Administration (FDA) has issued a safety announcement explaining that exceeding the maximum daily dosage of an over-the-counter (OTC) laxative containing either sodium biphosphate or sodium phosphate (Fleet brand, as well as store brands and generic formulations) can cause severe dehydration and serious imbalances in electrolytes (sodium, calcium, and phosphate). An FDA review of 54 case reports (identified in the medical literature from 1957 through August 2013 and in the FDA Adverse Event Reporting System database from 1969 to 2012) concluded that arrhythmias and serious damage to the heart or kidneys can result from electrolyte imbalances secondary to overuse of OTC sodium biphosphate or sodium phosphate. Among the 54 cases of laxative abuse reported, 13 of the patients died. These serious adverse effects occurred from exceeding the dose of either oral or rectal forms (enemas) of the laxatives. Overdosage may be the result of a single dose that exceeds the recommended daily dosage or multiple normal doses administered within one day.

Patients at higher risk for complications from large doses include children five years of age or younger; adults older than 55 years; patients with dehydration, kidney disease, bowel obstruction, or inflammation of the bowel; and patients who use medications that affect kidney function (including diuretics, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and nonsteroidal antiinflammatory drugs).

This isn't the first time that the FDA has issued a warning about dangers associated with high doses of oral sodium phosphate. In 2008 the agency cited concerns about the risk of acute phosphate nephropathy secondary to the use of high doses of the drug for bowel preparation prior to colonoscopy or other procedures. In acute phosphate nephropathy, a form of acute kidney injury, deposits of calcium-phosphate crystals develop in the renal tubules. The products involved in the 2008 safety alert were prescription products, Visicol and OsmoPrep, which now carry boxed warnings about the risk of acute kidney injury.

Nurses need to provide patient education regarding the use of these OTC products. Because of the increased risk in young children, parents and caregivers should be instructed never to administer oral products containing sodium biphosphate or sodium phosphate to children five years of age or younger without discussing it with a health care provider. Health care professionals, including pediatric NPs, should use caution when recommending oral use of these products in children five years of age or younger. Rectal forms of these products should never be used in children younger than two years.

Nurses should provide education concerning the risk of serious adverse effects from overuse of these drugs to all patients with any of the risk factors listed above. Patients should be well hydrated prior to taking products containing sodium biphosphate or sodium phosphate. In patients at high risk who use these laxatives, the FDA recommends assessment of serum electrolyte levels and renal function. Serum electrolytes and renal function should also be assessed in patients who retain a rectal dose for more than 30 minutes, those who are vomiting, and those who have signs of dehydration after use of the drugs.

The FDA also encourages all health care providers to report any adverse effects of an OTC sodium phosphate or biphosphate product to the FDA MedWatch program at http://www.accessdata.fda.gov/scripts/medwatch. To read the safety report, go to http://1.usa.gov/1cdeXIz.