Long-term efficacy of oral calcium polystyrene sulfonate for hyperkalemia in CKD patients

BACKGROUND Calcium polystyrene sulfonate (CPS) has long been used to treat hyperkalemia in patients with chronic kidney disease (CKD). However, its efficacy and safety profile have not been systematically explored. We investigated the long-term efficacy of oral CPS for treating mild hyperkalemia on an outpatient basis. METHODS We performed a retrospective analysis of ambulatory CKD patients who were prescribed CPS for > 1 week because of elevated serum potassium levels > 5.0 mmol/L. Patients were divided into four groups according to the length of time that they took a fixed dosage of CPS (Group 1, < 3 months; Group 2, 3-6 months; Group 3, 6-12 months; and Group 4, > 1 year). Response was defined as a decrease in the serum potassium level (> 0.3 mmol/L) after treatment with CPS. RESULTS We enrolled a total of 247 adult patients with a basal eGFR level of 30 ± 15 mL/min/1.73 m2. All patients took small doses of CPS (8.0 ± 3.6 g/d), and serum potassium decreased in a dose-dependent fashion. Serum potassium of all patients decreased significantly from 5.8 ± 0.3 mmol/L to 4.9 ± 0.7 mmol/L with CPS treatment (P < 0.001). The response rates were 79.9%, 71.4%, 66.7%, and 86.8% in Groups 1, 2, 3, and 4, respectively. No serious adverse effects were reported during CPS administration, though constipation was noted in 19 patients (8%). CONCLUSION Small doses of oral CPS are effective and safe for controlling mild hyperkalemia in CKD patients over a long period of time.