(936) Evaluation of Sodium Zirconium Cyclosilicate for Sulfamethoxazole/Trimethoprim-Induced Hyperkalemia

Introduction: Sulfamethoxazole/trimethoprim (SMX-TMP) is the drug of choice for various infections; however, its utilization may be limited by the adverse effect of hyperkalemia. Sodium zirconium cyclosilicate (SZC) is a potassium binder, which has been shown to lower potassium in patients with chronic kidney disease. The purpose of this study was to determine the safety and efficacy of SZC for patients experiencing SMX-TMP-induced hyperkalemia.

Methods: A multi-center retrospective analysis of patients receiving SMX-TMP and SZC therapy concomitantly from 1/1/21-7/1/24 was performed. Included patients were ≥ 18 years of age and received SMX-TMP for ≥ 48 hours after the first dose of SZC. Patients who initiated SZC > 48 hours prior to the first dose of SMX-TMP and those receiving SMX-TMP as prophylaxis were excluded. Efficacy was evaluated by potassium change from baseline, proportion of patients achieving normokalemia by 24 and 48 hours, and time to potassium normalization. Safety was assessed by evaluating hypokalemia occurrence while on SZC therapy.

Results: A total of 214 patients were reviewed and 19 were evaluated based on inclusion criteria. The average total daily dose of SMX-TMP was 915.8 mg or 12.5 mg/kg/day. Fourteen of the patients (74%) were on SMX-TMP for confirmed Stenotrophomonas maltophilia or Pneumocystis pneumonia infections. Seven patients (37%) received a loading dose of SZC 10g three times daily for 48 hours, prior to receiving 10g daily. The remaining 12 patients were started on maintenance dosing. The average difference in potassium at baseline and at the end of SZC therapy was 1.0 mmol/liter. Eleven patients out of 19 (58%) and 16 of 18 patients (89%) achieved normokalemia by 24 and 48 hours, respectively. The average time to potassium normalization was 1.8 days. There were no instances of hypokalemia while on SZC therapy.

Conclusions: SZC was efficacious at lowering elevated potassium in patients receiving SMX-TMP therapy without inducing hypokalemia. This suggests SZC may be considered in patients with treatment-limiting hyperkalemia due to SMX-TMP, especially when SMX-TMP is preferred therapy. To our knowledge, this is the first study evaluating SZC use due to SMX-TMP-induced hyperkalemia, and future studies are needed.