Evaluation of Sodium Polystyrene Sulfonate Dosing Strategies in the Inpatient Management of Hyperkalemia

Background: Hyperkalemia occurs frequently in an inpatient setting, for which sodium polystyrene sulfonate (SPS) is a common treatment modality. Few studies have investigated the dose-response of SPS. Objective: To quantify the change in serum potassium after 15-, 30-, and 60-g oral and 30-g rectal doses of SPS. Secondary objectives were to compare the proportion of patients attaining post-SPS dose normokalemia between dosing groups and to investigate the effect of certain characteristics on SPS dose-response. Methods: The reduction in serum potassium after 15-, 30-, and 60-g oral and 30-g rectal doses of SPS administered to adult inpatients was evaluated through a retrospective chart review. Ottawa Hospital Research Ethics Board approval was obtained prior to data collection. Results: A total of 118 patients were included in the analysis. Serum potassium levels were reduced by 0.39, 0.69, 0.91, and 0.22 mEq/L following 15-, 30-, and 60-g oral doses and a 30-g rectal dose of SPS, respectively. A greater proportion of patients (50% vs 23%) remained hyperkalemic in the 15-g versus the 60-g group (P = 0.018), and all patients in the rectal group remained hyperkalemic. No patient in any group experienced postdose hypokalemia. The influence of all studied interindividual characteristics on SPS dose-response was clinically nonsignificant. Conclusion: Mild hyperkalemia can be effectively treated with a single 60-g oral dose of SPS as monotherapy, with minimal risk of hypokalemia. Moderate to severe hyperkalemic episodes warrant alternative therapy. The potassium-lowering effect is correlated to SPS dose and is independent of interindividual characteristics.