Patiromer Treatment in Patients With CKD, Hyperkalemia, and Hyperphosphatemia: A Post Hoc Analysis of 3 Clinical Trials

Rationale & Objective Patients with chronic kidney disease (CKD), hyperkalemia (serum potassium [sK+] >5.0 mEq/L), and hyperphosphatemia experience poor clinical outcomes. Patiromer, a potassium binder that uses calcium as the exchange ion, may also reduce sP. We characterized the effect of patiromer on serum phosphorous (sP) in patients with CKD, hyperkalemia, and hyperphosphatemia. Study Design A post hoc pooled analysis of individual-level data from the AMETHYST-DN, OPAL-HK, and TOURMALINE trials of patiromer. Setting & Participants Patients with CKD and hyperkalemia. Exposure Patients treated with patiromer (8.4–33.6 g/day). Outcomes Mean changes from baseline in sP, sK+, serum calcium (sCa2+), and serum magnesium (sMg2+) after 2 and 4 weeks of treatment. Analytical Approach Descriptive statistics to summarize pooled data on the study outcomes from the three studies. Results 578 patients were included in the analysis. 86 patients (14.9%) had baseline hyperphosphatemia of whom 75.6% (n=65/86) had CKD stage 4/5. 31.1% (n=153/492) of patients with sP ≤4.5 mg/dL had CKD stage 4/5. Among patients with elevated sP and sK+ at baseline, the mean (SD) reduction in sP and sK+ after 4 weeks of patiromer treatment were –0.62 (1.09) mg/dL and –0.71 (0.51) mEq/L, respectively. Additionally, the mean (SD) reduction in sMg2+ in these patients was–0.25 (0.23) mg/dL while sCa2+ remained unchanged. Both sMg2+ and sCa2+ remained within the normal range. Patiromer was generally well tolerated, and no serious adverse events were considered related to patiromer. Limitations These were post hoc analyses, no placebo comparison due to the design of the original studies, and follow-up was limited to 4 weeks. Conclusions Reductions in sP and sK+ to the normal range were observed following 2 weeks of patiromer treatment and sustained during 4 weeks treatment among patients with non-dialysis dependent CKD, hyperkalemia, and hyperphosphatemia. Future controlled trials are needed to establish if patiromer is useful to reduce both sK+ and sP in hyperkalemic patients with CKD and hyperphosphatemia.