Aims: To evaluate efficacy and safety of RLY5016 (a non-absorbed, orally administered, potassium [K+]-binding polymer) on serum K+ levels in patients with chronic heart failure (HF) receiving standard therapy and spironolactone.
Methods and results: One hundred and five patients with HF and a history of hyperkalaemia resulting in discontinuation of a renin-angiotensin-aldosterone system inhibitor/blocker and/or beta-adrenergic blocking agent or chronic kidney disease (CKD) with an estimated glomerular filtration rate of <60 mL/min were randomized to double-blind treatment with 30 g/day RLY5016 or placebo for 4 weeks. Spironolactone, initiated at 25 mg/day, was increased to 50 mg/day on Day 15 if K+ was ≤5.1 mEq/L. Endpoints included the change from baseline in serum K+ at the end of treatment (primary); the proportion of patients with hyperkalaemia (K+ >5.5 mEq/L); and the proportion titrated to spironolactone 50 mg/day. Safety assessments included adverse events (AEs) and clinical laboratory tests. RLY5016 (n= 55) and placebo (n= 49) patients had similar baseline characteristics. At the end of treatment, compared with placebo, RLY5016 had significantly lowered serum K+ levels with a difference between groups of -0.45 mEq/L (P < 0.001); a lower incidence of hyperkalaemia (7.3% RLY5016 vs. 24.5% placebo, P= 0.015); and a higher proportion of patients on spironolactone 50 mg/day (91% RLY5016 vs. 74% placebo, P= 0.019). In patients with CKD (n= 66), the difference in K+ between groups was -0.52 mEq/L (P= 0.031), and the incidence of hyperkalaemia was 6.7% RLY5016 vs. 38.5% placebo (P= 0.041). Adverse events were mainly gastrointestinal, and mild or moderate in severity. Adverse events resulting in study withdrawal were similar (7% RLY5016, 6% placebo). There were no drug-related serious AEs. Hypokalaemia (K+ <3.5 mEq/L) occurred in 6% of RLY5016 patients vs. 0% of placebo patients (P= 0.094).
Conclusion: RLY5016 prevented hyperkalaemia and was relatively well tolerated in patients with HF receiving standard therapy and spironolactone (25-50 mg/day).
Trial registration: ClinicalTrials.gov NCT00868439.