Efficacy and safety of patiromer for hyperkalemia: a randomized, placebo-controlled phase 3 study

Background This is the phase 3 study in Japan designed to verify the superiority of patiromer over placebo using the change in serum potassium level (sK-level). Methods This study was a multicenter, randomized withdrawal study targeting Japanese hyperkalemic patients. It consisted of the run-in period and the double-blind period. The run-in period was an active single-arm, open-label period (4 or 5 weeks). The double-blind period was a randomized, placebo-controlled, parallel-group, double-blind period (4 weeks). Patients whose sK-level was within the normal range at week 4 or 5 of the run-in period entered the double-blind period. Patients who entered the double-blind period were randomly assigned to the patiromer group or the placebo group. Results As a result of the primary analysis, the change of the sK-level (95% CI) from baseline to week 4 in the double-blind-period, was - 0.02 (- 0.19, 0.15) mmol/L in the patiromer group, and 0.78 (0.60, 0.96) mmol/L in the placebo group, with a statistically significant difference between the two treatment groups (p < 0.001). Similarly, statistically significant differences were also observed between the two groups at weeks 1, 2, and 3. Furthermore, the proportion of patients whose sK-level was maintained within the normal range were statistically significantly higher in the patiromer group than in the placebo group at all time points. No adverse events requiring particular attention were observed. Conclusion Patiromer can improve hyperkalemia by lowering sK-level and can suppress the recurrence of hyperkalemia with continued administration, and is safe and easy-to-use for a wide range of patients.