Adverse GI Events
Results indicated that sodium polystyrene sulfonate use vs. nonuse was associated with a higher risk of an adverse GI event over the following 30 days (37 events [0.2%]; incidence rate, 22.97 per 1000 person-years vs 18 events [0.1%]; incidence rate, 11.01 per 1000 person-years) (hazard ratio, 1.94; 95% CI, 1.10-3.41).
Researchers explained that the findings remained consistent in additional analyses, including the subpopulation with baseline laboratory values (hazard ratio, 2.91; 95% CI, 1.38-6.12). Intestinal ischemia/thrombosis was the most common type of GI injury, they said.
“So what should clinicians do?” the editorial asks. “Given the evidence, sodium polystyrene sulfonate should not be used to reduce serum potassium levels. 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 se rum potassium.”
A newer cation-exchange resin, patiromer, has recently been approved for lowering serum potassium levels in patients with chronic hyperkalemia. Patiromer is a polymer-based agent that binds potassium in the colon in exchange for calcium. Patiromer, marketed as Veltassa, is not available as a generic drug and costs about $1,000 per month compared with about $10 per month for sodium polystyrene sulfonate, according to the article.
The commentary did not suggest that was the best alternative to sodium polystyrene sulfonate at this point, however, stating, “Given the lack of evidence of GI adverse events related to patiromer, it may be tempting to choose this drug rather than sodium polystyrene sulfonate. However, studies of patiromer have been small and short-term (three days to eight weeks), and the drug has not been widely used in practice. It is possible that this drug may also cause significant adverse events.”
A presentation at the recent American Nephrology Nurses Association Meeting, involving researchers form the Stratton VAMC in Albany, NY, and the Salt Lake City VAMC, suggested use of patiromer remains limited with VA patients.3
The retrospective cohort study sought to describe treatment patterns in veterans with hyperkalemia—either with sodium polystyrene sulfonate or with patiromer, the novel sodium-free, non-absorbed potassium (K+) binder. To do that, researchers collected data from the VA Corporate Data Warehouse from Jan. 1, 2016 until Dec. 31, 2017.
Included were patients with evidence of hyperkalemia, defined as K+ ≥5.1 mEq/L, and heart failure, diabetes mellitus, or CKD prior to index. Follow-up lasted until discontinuation, death or six months post index.
The study team measured utilization parameters including initial dose, Rx fills, days supplied/fill, proportion of days covered, and percentage of patients with a proportion of days covered greater than 80%.
Results indicated that 193 patients with hyperkalemia were treated with patiromer at index vs. 8,942 treated with sodium polystyrene sulfonate. The study determined that, in the patiromer group, median age was 69 years, 24% were African American, 96% had CKD, and 37% had heart failure. In the SPS group, median age was 70 years, 22% were African American, 68% had CKD, and 27% had heart failure. The initial doses were 8.4 g patiromer and 15 g sodium polystyrene sulfonate.
Researchers calculated that the median number of prescription fills were two in the patiromer group and one in the SPS group. At the same time, median days supplied/prescription fill was 30 in the patiromer group and three in the SPS group, while median PDC was 41% in the patiromer group and 2% in the SPS group. The PDC ≥80% was 16% in the patiromer group and 1% in the SPS group.
“This descriptive analysis among US veterans showed contrasting utilization patterns for patients exposed to patiromer and SPS for the treatment of hyperkalemia,” the researchers explained. “The days supplied/prescription, the number of prescription fills, and the higher PDC suggest a more chronic treatment pattern for patiromer and an episodic pattern for SPS. Given the limited number of patiromer users in this database, these findings warrant further study.”
Noel JA, Bota SE, Petrcich W, Garg AX, et. Al. Risk of Hospitalization for Serious Adverse Gastrointestinal Events Associated With Sodium Polystyrene Sulfonate Use in Patients of Advanced Age. JAMA Intern Med. 2019 Jun 10. doi: 10.1001/jamainternmed.2019.0631. [Epub ahead of print] PubMed PMID: 31180477; PubMed Central PMCID: PMC6563537.
Parks M, Grady D. Sodium Polystyrene Sulfonate for Hyperkalemia. JAMA Intern Med. 2019;179(8):1023-1024. doi:10.1001/jamainternmed.2019.1291
Gosmanova EO, Kovesdy CP, Woods SD, et al. Disparities in real-world utilization patterns of potassium binders in US veterans with hyperkalemia. Abstract of a presentation at the 2019 American Nephrology Nurses Association National Symposium, April 14-17, 2019, Dallas Texas.