Comparative Efficacy of Sodium Zirconium Cyclosilicate and Sodium Polystyrene Sulfonate for Acute Hyperkalemia: A Retrospective Chart Review

Background: Sodium polystyrene sulfonate (SPS) is a nonselective sodium-potassium exchange resin commonly used along with intravenous (IV) insulin, albuterol, furosemide, and/or calcium for the treatment of acute hyperkalemia. Sodium zirconium cyclosilicate (SZC) is a newer non-absorbed exchange resin that preferentially increases fecal potassium excretion from the gastrointestinal tract. Limited data exists on the efficacy of SZC for the treatment of acute hyperkalemia. Objectives: To assess the achievement of normokalemia (serum potassium level [K+] 3.5-5.2 mmol/L) within 24 hours after administration of SZC or SPS in combination with insulin regular IV push. Methods: A multicenter, retrospective chart review (2020-2021) using electronic medical records at an academic health system. The study population included adult patients receiving one or more doses of SZC or SPS in combination with IV insulin for acute hyperkalemia (K+ >5.2 mmol/L). Patients receiving dialysis were excluded. Serum chemistries were assessed at baseline and an additional 2 values within 24 hours to determine normokalemia and hypokalemia at each follow-up. Results: Of 141 patients included, 51 received SZC and 90 received SPS. Normokalemia at the first follow-up was achieved in 51.0% of patients receiving SZC and 46.7% of patients receiving SPS ( P = .622) and was sustained in 35.3%versus 44.4% ( P = .289) of patients within 24 hours. Mean serum potassium differences from baseline to first follow-up were similar between SZC and SPS groups (0.9 mmol/L vs 1.0 mmol/L). Hypokalemia within 24 hours of administration occurred in 4 patients—1 in SZC, 3 in SPS. Conclusion: Both SZC and SPS yielded similar rates of normokalemia achievement with IV insulin for the treatment of acute hyperkalemia. Further prospective studies are needed to confirm these findings.