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Sodium polystyrene sulfonate use tied to increased risk for adverse GI events

Sodium polystyrene sulfonate, a common treatment for hyperkalemia, was associated with an increased risk for serious adverse gastrointestinal events, suggesting that clinicians should exercise caution when prescribing it, according to study results published in JAMA Internal Medicine.

“Despite its long-standing and widespread use, there have been several case reports of serious and often fatal gastrointestinal injury associated with sodium polystyrene sulfonate use,” J. Ariana Noel, MD, of the department of medicine at the University of Ottawa, Ontario, Canada, and colleagues wrote. “This injury was originally attributed to coadministration of sodium polystyrene sulfonate with 70% sorbitol as a premixed suspension agent, and the [FDA] issued a black box warning against their concurrent use. Nevertheless, case reports of [gastrointestinal] injuries, primarily colonic necrosis, have persisted with the use of sodium polystyrene sulfonate as a solo agent.”

To determine the risk for adverse gastrointestinal events, researchers conducted a population-level, retrospective matched cohort study of adults aged 66 years and older who were treated with sodium polystyrene sulfonate in Ontario, Canada, between Apr. 1, 2003, and Sep. 30, 2015. Multiple databases in the Institute for Clinical Evaluation Sciences were used to obtain patient information.

Study participants continued follow up until the occurrence of an adverse gastrointestinal event, 30 days, emigration from Ontario, or death.

Out of 1,853,866 eligible patients, 27,704 (1.5%) with a mean age of 78.5 years received sodium polystyrene sulfonate. Of those, 20,020 were included in the study and matched with 20,020 nonusers.

Within the 30-day follow-up period, there were 37 adverse gastrointestinal events (0.2%; incidence rate, 22.97 per 1000 person-years) among those who received sodium polystyrene sulfonate and 18 events (0.1%; incidence rate, 11.01 per 1000 person-years) among those who were not (HR = 1.94; 95% CI, 1.1-3.41).

Addition analyses yielded similar results, including an analysis of subpopulation with baseline laboratory values (HR = 2.91; 95% CI, 1.38-6.12).

The most common gastrointestinal injury among the study population was ischemia/thrombosis.

“Given the evidence, sodium polystyrene sulfonate should not be used to reduce serum potassium levels,” Monica Parks, MD, of the department of medicine, University of California, San Francisco, and Deborah Grady, MD, MPH, department of medicine, University of California, San Francisco, San Francisco Veterans Affairs Medical Center, and Deputy Editor of JAMA Internal Medicine, wrote in an editorial accompanying the study. “There are a number of other approaches to treating elevated serum potassium levels, including dietary restriction of potassium, potassium-wasting diuretics, and lower doses or discontinuation of medications that increase serum potassium.” – by Erin Michael

Disclosures: Grady, Noel and Park report no relevant financial disclosures. Please see the full study for all other authors’ relevant financial disclosures.