Risk of Serious Harm from Sodium Phosphate Products for Constipation

On Jan. 8, 2014, the Food and Drug Administration (FDA) issued an alert to patients and health care providers warning about serious, and even fatal, kidney and heart risks from exceeding the recommended dose of over-the counter (OTC) sodium phosphate products used to treat constipation. Three days later, subscribers to WorstPills.org received an e-alert warning them of these risks.

Sodium phosphate laxatives are sold under the brand name FLEET or as store-brand or generic products. These OTC products come both as oral solutions (taken by mouth) and enemas (taken rectally). It is important that patients read the labels and follow the instructions exactly, since most serious reports of harm came from people inadvertently taking a dose higher than recommended.

Overdosing on these products can lead to severe dehydration and blood electrolyte abnormalities (predominantly high blood phosphate and sodium levels and low calcium levels), which can cause serious complications such as acute kidney failure, abnormal heart rhythms and death.

Basis for safety alert

Prior to issuing its alert, the FDA reviewed its Adverse Event Reporting System database for information from 1969 through 2012, as well as medical literature from 1957 through August 2013. The agency was looking for any cases of serious adverse events associated with oral or rectal use of OTC sodium phosphate drug products used to treat constipation.

In this review, the agency identified 54 such cases: 25 adults and 29 children. Ten of these had been reported directly to the agency, and 44 appeared in the medical literature. Although serious adverse events due to OTC sodium phosphate drug products are rare, the cases found by the FDA almost certainly represent a small fraction of the patients who have been harmed by such products over the past six decades.

The patients’ ages varied greatly, from an 8-day-old newborn to a 97-year-old adult, but for the most part they involved older adults and children younger than 5 years old.

Close to two-thirds of the adults and almost half of the children experienced dehydration, kidney disease, acute colitis or delayed bowel emptying — often while simultaneously using drugs that act on renal function, such as diuretics, angiotensin-converting enzyme (ACE) inibitors, angiotensin II receptor blockers (ARBs) and nonsteroidal anti-inflammatory drugs (NSAIDs).

According to the FDA, all of the serious cases were “characterized by dehydration and/or electrolyte disturbances with associated complications such as acute kidney injury and death.” In terms of severity of the adverse event reported, it did not matter whether the patient took an oral or a rectal product. Close to half of adult cases (12 of 25) and 3 percent of pediatric cases (1 of 29) were fatal.

The rest of the cases were considered life-threatening in more than two-thirds of the adults and all of the children. Problems seen in these cases included sudden onset of difficulty breathing, altered mental status and heart abnormalities. Four adults and three children needed dialysis for acute kidney injury. Two adults and two children required surgery for bowel problems.

Fifty of the cases included information regarding the dose taken, and in 60 percent of the children and 70 percent of the adults, the recommended dose was exceeded, either through taking a single dose that was larger than specified on the label or through taking the product more frequently than specified. In 40 percent of the pediatric cases for which the dose was reported, the patients were young children for whom there is no FDA-proposed safe and effective dose. In fact, for nine cases involving children less than 2 years old who were given a sodium phosphate enema and two cases involving children younger than 5 years old who had received an oral product, the dose administered was comparable to one recommended for an adult or older child.

High-risk groups

Based on the FDA’s analysis of the identified cases, people who are at greatest risk for serious harm from taking more than the recommended dose of sodium phosphate products include:

• children younger than age 5;
• adults older than 55 years;
• individuals who are dehydrated;
• patients with kidney disease, heart failure, bowel obstruction or bowel inflammation; and
• patients taking medicines that can affect kidney function, including diuretics, ACE inhibitors, ARBs and NSAIDs.

What You Can Do

If you have any of the risk factors listed above, talk to your primary health care provider before using any OTC sodium phosphate product.

You should never take more than one dose of these products in 24 hours, and you should always carefully read and follow the dosage instructions provided on the label.

Do not give the oral form of sodium phosphate to children 5 years or younger without consulting your child’s pediatrician. Never give the rectal form of these drugs to children younger than age 2.

You should seek immediate medical attention if you or your child experiences any symptoms of kidney failure after using a sodium phosphate product, such as nausea; vomiting; loss of appetite; drowsiness; sluggishness; decreased urine output; or swelling of the ankles, feet or legs.

Report any adverse effects related to OTC sodium phosphate products to the FDA MedWatch program. To read the full text of the FDA announcement, visit http://www.fda.gov/Drugs/DrugSafety/ucm380757.htm.