Comparison of sodium zirconium cyclosilicate and sodium polystyrene sulfonate in the treatment of acute hyperkalaemia

Sodium polystyrene sulfonate (SPS) and sodium zirconium cyclosilicate (SZC) have been used for treating acute hyperkalaemia. The pharmacodynamic properties of SZC suggest greater theoretical utility in the acute setting than SPS, but there is no clear guidance on an optimal potassium binder. This study evaluated the efficacy of SZC and SPS in the treatment of acute hyperkalaemia. This retrospective cohort study included adult hospitalised patients who had acute hyperkalaemia (serum potassium level ≥5.5 mmol/L) and were treated with either SZC or SPS from April 2021 to August 2023. The primary outcome was time to first occurrence of potassium normalisation which was evaluated using Cox regression analysis. Secondary outcomes included potassium normalisation, serum potassium level trends, newly initiated dialysis following acute hyperkalaemia, in-hospital death and adverse events. The study included 46 patients with 17 in the SZC group and 29 in the SPS group. Potassium normalisation was attained in 16 (94%) in the SZC group and 27 (93%) in the SPS group and, of those, five (29%) in the SZC group and five (17%) in the SPS group attained normal potassium levels within 8 hours (HR 1.91, 95% CI 0.55 to 6.56). Statistically, neither SZC nor SPS was more efficacious; however, the quicker onset of SZC could provide a clinically meaningful difference in the treatment of acute hyperkalaemia.