Evaluation of sodium zirconium cyclosilicate usage for hyperkalaemia secondary to sulfamethoxazole/trimethoprim therapy

Background Sulfamethoxazole/trimethoprim is utilized to treat various infections, but its use can be limited by hyperkalaemia. Sodium zirconium cyclosilicate is a potassium binder, which has been shown to lower potassium in chronic kidney disease. Objectives To determine the safety and efficacy of sodium zirconium cyclosilicate for patients experiencing sulfamethoxazole/trimethoprim-induced hyperkalaemia. Methods Patients receiving treatment with sulfamethoxazole/trimethoprim and sodium zirconium cyclosilicate therapy concomitantly for at least 48 h between 2021 and 2024 were identified. Efficacy was evaluated by potassium change from baseline, proportion of patients achieving normokalaemia by 24 and 48 h, and time to potassium normalization. Safety was assessed by evaluating hypokalaemia occurrence while on sodium zirconium cyclosilicate therapy. Results There were 22 patients included. The median total daily dose of sulfamethoxazole/trimethoprim was 960 mg or 15 mg/kg/day. Fifteen patients (68%) were treated for confirmed Stenotrophomonas maltophilia or Pneumocystis pneumonia infections. Eight patients (36%) received a loading dose of sodium zirconium cyclosilicate 10 g three times daily for 48 h prior to receiving 10 g daily. The median difference in potassium at baseline and the end of sodium zirconium cyclosilicate therapy was 0.9 mmol/L. Fourteen patients of 22 (64%) and 19 of 21 patients (90%) achieved normokalaemia by 24 and 48 h, respectively. The median time to potassium normalization was 23.5 h. There were no instances of hypokalaemia while on sodium zirconium cyclosilicate therapy. Conclusions Sodium zirconium cyclosilicate was efficacious at lowering elevated potassium in patients receiving sulfamethoxazole/trimethoprim therapy without inducing hypokalaemia. This suggests sodium zirconium cyclosilicate may be considered in patients with treatment-limiting hyperkalaemia due to sulfamethoxazole/trimethoprim, especially when sulfamethoxazole/trimethoprim is preferred therapy.