Patiromer Shown Safe and Effective in Three Clinical Trials in Patients with Hyperkalemia

Austin, Texas—Veltassa® (patiromer), a sodium free, nonbasorbed potassium binder, is approved for treatment of patients in the United States and the European Union with hyperkalemia. Matthew Weir, MD, and colleagues recently conducted an analysis to examine the consistency of lowering serum potassium in trials of patiromer for hyperkalemia. Results of the analysis were reported during a poster session at the NKF 2018 Spring Clinical Meetings in a poster titled Consistency of Serum Potassium Effects in Patiromer Clinical Trials.

The researchers conducted a pooled analysis of data from three phase 3 clinical trials: (1) AMETHYST-DN, OPAL-HK, and TOURMALINE. AMETHYST-DN was a 52-week, open label study; OPAL-KH was a 12-week, two-part, single-blind study with a 4-week treatment phase and an 8-week placebo-controlled randomized withdrawal phase; and TOURMALINE was a 4-week, open label study.

Eligible patients in all three studies had baseline serum potassium >5.0 mEq/L (as measured by local laboratory results); inclusion criteria for patients in AMETHYST-DN and OPAL-HK were estimated glomerular filtration rate 15 to 59 mL/min/1.73 m2 and be taking one or more renin-aldosterone system (RAAS) inhibitors. Patients in AMETHYST-DN also had to have type 2 diabetes mellitus. Overall, participants were 62% male, 96% white, and mean age was 66 years; 96% had hypertension, 65% had chronic kidney disease (CKD) stage 3b or higher, and 42% had serum potassium ≥5.5 mEq/L at baseline.

Patients were randomized to potassium starting doses by baseline serum potassium level (8.4 g/d to 33.6 g/day in AMETHYST-DN; 8.4 g/d to 16.8 g/d in OPAL-HK) or to potassium dosing (8.4 g/d ± food in TOURMALINE). The poster reported results over the first 4 weeks of each study by baseline serum potassium level strata (<5.5 mEq/L to ≥5.5 mEq/L).

Efficacy results were available for a total of 653 patients: AMETHYST-DN, 304; OPAL-HK, 237; Tourmaline, 112. Patients with mild hyperkalemia at baseline had serum potassium reduced to <5.0 mEq/L by day 3. Patients with moderate-to-severe hyperkalemia (≥5.5 mEq/L) had serum potassium reduced to <5.5 mEq/L by week 1 or 2. Overall, 629 participants (96%) had serum potassium levels 3.5 mEq/L to 5.0 mEq/L during weeks 1 to 4.

Thirty-two percent of participants (n=209) reported adverse events; the most common adverse events were constipation (6%) and diarrhea (3%). There were no severe adverse events. The rate of hypokalemia, defined as serum potassium level <3.5 mEq/L, was 1.5%.

“In conclusion, the consistency of clinical effect of patiromer has been shown in three trials of the treatment of hyperkalemia, predominantly in participants with CKD and diabetes on RAAS inhibitor therapy,” the researchers said.

Source: Weir M, Mayo M, Yuan J, Conrad A. Consistency of serum potassium effects in patiromer clinical trials. Poster presented at the National Kidney Foundation 20187 Spring Clinical Meetings, April 10-14, 2018, Austin, Texas.

The study was sponsored by Relypsa, Inc., a Vifor Pharma Group Company.