Both patiromer and sodium polystyrene show efficacy in lowering the potassium content of infant milk formula, but they also alter other electrolytes, according to a poster presentation from the American Society of Nephrology’s Kidney Week 2020 Reimagined virtual conference.

Vimal Chadha, MD, and colleagues from Children’s Mercy in Kansas City, Missouri, pretreated the renal infant milk formula Similac® PM 60:40 with 3 different concentrations of  sodium polystyrene (3.4, 6.8, and 13.6 g/L) and patiromer (8.4, 16.8, and 33.6 g/L). After 30 minutes, potassium concentrations had decreased 15%, 33%, and 61% with sodium polystyrene and 7%, 15%, and 22% with patiromer at the different strengths, respectively.

However, the resin that exchanges sodium for potassium increased the sodium content of the milk by 87%, 239%, and 300%, respectively, whereas patiromer resulted in small decreases in sodium (3%, 6%, and 9%, respectively)..

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Sodium polystyrene reduced the calcium content of milk by as much as 40%, whereas patiromer, which exchanges calcium for potassium, increased calcium by as much as 43%.

Both potassium binders decreased magnesium: as much as 69% with sodium polystyrene and 38% with patiromer.

“Knowledge of these electrolyte changes is crucially important when caring for patients with renal disease as these patients have abnormal homeostasis and they are also vulnerable to negative consequences of any electrolyte imbalance,” Dr Chadha’s team stated.

Disclosure: This clinical trial was supported by Relypsa. Please see the original reference for a full list of authors’ disclosures.


Chadha V, Oladitan L, Tower J, et al. Patiromer vs kayexalate: comparison of potassium binding efficacy and impact on other electrolytes in infant milk formula Similac PM 60:40. Presented at: Kidney Week 2020 Reimagined, October 19-25, 2020. Poster PO1444.