Patiromer Reduces Potassium in CKD Patients Taking RAAS Inhibitors

The new oral potassium binder patiromer effectively lowers serum potassium levels in patients with chronic kidney disease (CKD) who are being treated with renin-angiotensin-aldosterone system (RAAS) inhibitors, reports a trial in the New England Journal of Medicine.

The multicenter study included 243 patients with stage 3 or 4 CKD who were taking RAAS inhibitors and had a serum potassium level of 5.1 to less than 6.5 mmol/L. All received 4 weeks of treatment with patiromer. The starting dose was 4.2 or 8.4 g twice daily. Patients whose potassium level decreased to the target range (3.8 to less than 5.1 mmol/L) were eligible for an 8-week randomized withdrawal phase, with one group continuing to receive patiromer and the other switching to placebo. Changes in potassium level were compared between groups.

The mean reduction in serum potassium during the initial treatment phase was 1.01 mmol/L, and 76 percent of patients reached the target range by 4 weeks. Among 107 patients enrolled in the withdrawal phase, potassium levels increased by 0.72 mmol/L within 4 weeks for those switching to placebo, compared with no change for those continuing to receive patiromer. The rates of recurrent hyperkalemia (potassium level 5.5 mmol/L or higher) were 60 percent versus 15 percent, respectively. During the initial treatment phase, mild to moderate constipation occurred in 11 percent of patients and hypokalemia in 3 percent.

Patiromer—a nonabsorbed polymer that binds potassium in exchange for calcium—was developed to meet the need for effective outpatient treatments for hyperkalemia. This two-phase trial supports its effectiveness in reducing potassium levels and the rate of recurrent hyperkalemia in CKD patients taking RAAS inhibitors. Hypokalemia appears to be an infrequent and reversible event in patients taking patiromer [Weir MR, et al. Patiromer in patients with kidney disease and hyperkalemia receiving RAAS inhibitors. N Engl J Med doi: 10.1056/NEJMoa1410853].